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Timber for marine and fresh water construction

by A. C. Oliver, M.Sc., A.l.W.Sc.

Edited and metricated

by W. H. Brown, F.I.W.Sc.

Published by

Timber Research and Development Association

Hughenden Valley, High Wycombe, HP14 4ND

Buckinghamshire, England


Printed in Great Britain by Page Bros. (Norwich) Limited Norwich

Published 1963 Reprinted 1964 Revised 1967 Revised and metricated 1974

@ Timber Research and Development Association 1974


Contents

paw 5 Introduction

7 Properties of timber as a constructional material

9 Utilization of timber

9 River bank protection

9 Sea defence works

9 Groynes

12 Wave screens and revetments

12 Wharf and jetty construction

12 Piling

16 Fender piles

18 Decking

18 Rubbing pieces

19 Lock gates

28 Marinas and yacht havens

31 Joint construction

31 Bolts and coach screws

31 Split ring connectors and shear plates

31 Nails and spikes

31 Steel plates

35 Environmental hazards

35 Mechanical damage

35 Fenders

35 Rubbing pieces

35 Sea defence groynes

35 Biological attack

35 Fresh water

36 Salt water

36 Marine borers

36 The shipworm

37 The gribble

37 Prevention of biological deterioration

37 Natural durability-Fungal decay

40 Natural durability-Marine borer attack

40 Wood preservation

41 Other methods of preventing marine borer attack


Contents

page 43 Suitable timbers

41 Table I Degree of resistance to marine borer attack of certain

timbers in Table II

56 Table II Properties and working characteristics of suitable timbers

60 Table III Sizes and availability of suitable timbers

63 Acknowledgements

64 Bibliography


Introduction

The aim of this publication is to describe the use of timber for marine and fresh

water constructional purposes. It indicates how timber can provide a solution to many of the problems confronting dock, harbour and river board engineers

and others, concerned with water construction. With a knowledge of the

hazards to which timber may be exposed, and careful selection of the species

with the most appropriate properties for the job, a satisfactory and long lasting

structure can be obtained at relatively low cost.

The principle functions of marine and fresh water structures where timber is

utilized and which are described here are:-

(a) The prevention of erosion of the sea coast and of river and canal banks.

(b) The construction of wharfs, jetties, docks and dock gates, and the protection

of such structures by fendering and rubbing pieces.

(c) The construction of marinas and yacht havens.


Properties of timber as a constructional material

Some knowledge of the properties of timber will assist in making the most

suitable selection of material for a particular use. This section is devoted to a

brief discussion of some of the more important properties of timber, and how

these can be employed by the designer, specifier and engineer concerned with

marine and fresh water construction.

A detailed presentation of the properties of individual timbers is to be found on

pages 43-55. Table II provides data on the strength, working qualities, durability

and treatment characteristics of selected timbers, and Table III summarizes

commonly available lengths and dimensions.

Anyone familiar with the use of timber will have appreciated the variation of

strength properties that are associated with ‘grain’. This term is widely used in

the timber-using industry to cover many characteristics, such as texture or rate

of growth. In this booklet, its use will be confined to the following definition:

The grain of the timber is the direction of the principal structural elements in the

wood, i.e., fibres or tracheids; this can be demonstrated by a grain detector. If

this grain is not parallel to the edges of a board, then the strength will be reduced

in an amount proportional to that deviation. Thus timber can be cut from the log

to have diagonal grain, or it may have spiral grain if it comes from a tree which

has spiral growth. If, for example, high bending strength is required, it is neces-

sary to select straight-grained material. In other situations, i.e., rubbing pieces,

grain deviation such as ‘interlocked grain’ and ‘wild grain’ will be of advantage

as these deviations reduce the tendency to split when the wood is subjected to

mechanical damage.

Below a level of about 25-30% moisture content, the strength of timber increases

with drying. However, in all the situations and uses of timber described in this

booklet, the moisture content is unlikely to fall greatly below this moisture level

for long periods and so all strength properties are quoted for the green (ave.

30%) condition. (See Table Il.)

In most timbers a visual distinction can be made between sapwood and heart-

wood, sapwood usually being lighter in colour than the heart. Sapwood is

defined as: The layer of wood next to the bark, 12 mm to 75 mm or more wide

that is actively involved in the life processes of the tree. Under most conditions

sapwood is more susceptible to decay than heartwood; as a rule, it is more

permeable to liquids than heartwood. Sapwood is not essentially weaker or stronger than heartwood of the same species.

The heartwood of timber varies in durability; timbers which are very durable

can be successfully employed to provide a permanent structure in the untreated

state. If timber with low durability is employed, preservation will be more effective

in species with permeable heartwood or in timber with a large amount of sap.

wood. (See Table Il.)

Timber presents few problems during construction. It is light, compared with

most alternative materials, has a high strength/weight ratio, and is easy to

handle. These are particularly useful properties at sites where access and

transportation are main problems.

From the viewpoint of flexibility in construction, timber is pre-eminent. For

example, it is seldom possible to predict the optimum height of a groyne in

relation to the beach, and, even if this were possible, changing conditions would

necessitate adjustment. Timber planking is a very practical method of con-

struction, permitting ready adjustment of level. In general, in situ repair or

alteration of timber structures is a much simpler operation than with other materials.

7


Timber withstands shock loads caused by the sea and shipping better than

many other materials, and this property of resilience has obvious advantages

in marine work where wind, wave or impact loading, produces the highest

stresses. These stresses are of short duration, thus the short term loading

characteristic peculiar to timber is of great importance in marine construction.

The resilient characteristic is rationalized in the adoption of permissible short

term stresses of from one-and-a-half to twice the dead load stresses.

Comparisons with other materials are usually based on the green stresses for

timber given in Table 3, of CP112:1967: Imperial Units, or 1971 : Metric Units.

Of all constructional materials, timber is unique in that it does not corrode.

Corrosion, coupled with abrasion, may result in the loss of thickness in steel,

or exposure of concrete reinforcement.

Generally timber drives well, but this will depend on the character of the under-

lying strata. If driven into very soft ground, its buoyancy may cause floating out.

Light hammers and large drops can be used successfully for driving timber

piles with the knowledge that no damage can be caused to the pile. This factor

can be of economic importance, especially when driving over water, when

expensive temporary staging may be required, or when access is restricted to

low tide periods. There is divergence of opinion on which are the most suitable

species for driving. Softwoods are often driven with a metal shoe, but this may be

unnecessary when dense hardwoods are employed. Steel bands may be

placed around the top of a pile to prevent splitting during driving. Alternatively,

expanded metal caps can be used, which, after the first blow, become embedded

in the timber.


Utilization of timber

River bank protection In many navigable rivers, fast flowing currents caused by steep gradients, heavy

rainfall, tidal action, or the passage of boats or shipping may cause bank erosion

which can be particularly severe when the banks are of earth or soft rocks. If

this erosion is allowed to proceed unchecked, it may result in the collapse of

banks, flooding of neighbouring land and silting up of navigable channels.

The type of bank protection adopted is usually related to the amount of river

traffic. In upper reaches of rivers where only light traffic occurs, light forms of

construction using local timber are often adopted. An example is faggotting,

where bundles of brushwood are staked or weighted down and act as a protec-

tion to river banks subjected to scour. Spile posts and brushwood revetments

are sometimes used in rivers where heavy stones cause bank scour. They

consist of vertical posts of regular intervals along the bank around which brush-

wood is woven. Fascine mattresses of hazel, willow or birch are also used for

bank reinforcement.

All these forms of bank protection provide a cheap method of preventing

erosion. None of them can be considered very permanent when they are con-

structed of non-durable timber. Bank protection in the larger rivers and canals,

where heavy traffic occurs, requires the use of more substantial and permanent

structures. Types of timber construction include a tied post and plank system

in which a wall constructed from timber piles and horizontal planking is tied

back to an anchorage. Waling may be used at the tie level. Alternatively, timber

sheet piling which is held in position by wiring to anchor stakes, or by timber

waling, or horizontal planking with piles or stakes can be employed.

As all timber above the water line is subjected to a severe decay hazard, it is

essential that durable species or preservative treatment is employed. In estuaries

where salinity reaches the level where marine borers can survive, extra pre-

cautions similar to those recommended for marine situations must be

considered.

Sea defence works Along our coasts man has for centuries attempted to prevent erosion by the

sea which is constantly removing land from some areas, while beach material

is being deposited elsewhere. Changes in the outline of our coasts, silted ports,

and evidence of submerged forests are all indications of the importance of coast

erosion and accretion. Storms and consequential flood damage are reminders

that we ignore the sea at our peril. Tidal surge is a classic example of high

short term loading, which timber is particularly well fitted to resist.

Many different types of construction are employed on our coasts to combat

erosion. Natural defences of dunes, shingle banks and ridges are supplemented

and extended by clay banks, concrete walls, concrete blocks, wave screens and

revetments. The success of all these defences depends on the amount of beach

material which can be retained on the foreshore. The most widely used method

of doing this is by the installation of groynes. There are many local factors which

will influence their effectiveness and these should be taken into account when

considering design, length, spacing and height of groynes.

Groynes Along the coasts where erosion or accretion occur, a littoral drift of beach

material can be detected running more or less parallel to the shore. The function

of sea defence groynes is to take advantage of this littoral drift by trapping the

beach material. The beach is consequently built up and stabilized.

On sandy beaches another type of erosion can occur. This has been described

as frontal attack. When this occurs, sand may be drawn off the beach and

deposited off shore. Sandy beaches can exhibit slow summer build up and

violent storm drawdown. Wave breaks or permeable revetments parallel to the

beach are effective in reducing this storm drawdown when frontal attack occurs.

The south coast provides many examples of littoral drift in shingle, whereas in

East Anglia, sand drawdown by frontal attack is more common.

Solid timber groynes are usually between 30.0 m and 90.0 m long and 50 m to

150 m apart along the beach. Their height above the shore will vary according

to the amount of accretion they produce. A groyne height of 1.0 m is commonly

employed.

9


Sheet piling 75 mm x 225 mm

Depth of penetration not uniform

Figure 1 Sheet piling technique

Figure 2

Sheet piling technique. Brace pile

(land side)

water line

Existing ground

’ Cut on bevel to force piling together when driving

/

Wale 150mm Y 150mm or 150mm x 225mm

Fill

Tension in vertical pile

Pi!e 150 mm ,,’ 225 mm

10


Wale -

Water side

Sheet pile bolted to wale

Fill

Tension in vertical pile and sheet piling

Sheet piling technique. Brace pile (water side)

Timber sheet piles

\

Figure 4 Sheet piling technique. Filled

sheet piles as breakwater

Timber kerb

Sand, gravel, earth or stone fill

/

Tie rod

Existing ground


Home-grown tree trunks (often oak) are used in certain parts of Sussex as land

ties for groynes. They are placed on the leeside to prevent overturning as a

result of beach material accumulating on the ‘weather side’ of groynes. In

certain areas, 100 mm x 150 mm or 75 mm x 225 mm vertical timber sheet piling

is employed in groyne construction below beach level, in order to improve

stability. When this type of groyne is used, normal horizontal planking may be

placed on to the sheet piling.

In Sussex and East Anglia trials have been carried out using permeable groynes.

Although work at the Hydraulics Research Laboratory indicated that these

groynes were not as effective as solid timber groynes, some authorities still

use them. In the ‘Mobbs’ permeable groyne, the construction takes the form of

3.0 m long sections which run in a zig-zag down the beach. At each angle a

225 mm x 225 mm king pile is driven and on the seaward side, 150 mm x 225 mm

top and bottom horizontal walings, 1.5 m apart vertically, arefixed. Softwood pole

thinnings 2.4 m long are then fixed to these walings at 200 mm centres. The

consumption of timber is roughly comparable on this design of permeable

groyne with a conventional solid groyne.

Wave screen and These are frequently employed as ancillary structures to a sea defence groyne revetments system. Wave screens are permeable structures and consist of a line of spaced

vertical piles about 225 mm x 225 mm in section and are joined by 150 mm x

225 mm horizontal walings. They are arranged in lines parallel to the coast in

the upper part of the tidal range. Their function is to reduce ‘drawdown’ during a

storm and to break the force of the waves, to cause wave borne beach material

to be deposited, and thereby encouraging accretion. They would be employed

more widely but are considered to reduce the amenity value of a sandy beach.

Revetments and breastworks are impermeable timber barriers running parallel

to the foreshore. They are sited above high water mark and consist of a double

line of piles, with waling and planking. The space between these double lines is

Wharf and jetty filled with earth or beach material and thus form a reinforced earthwork.

construction Timber used for sea defence construction include pitch pine, jarrah, greenheart,

Piling elm, Douglas fir, oak, and opepe.

Timber may be used for many purposes in wharf and jetty construction, but the

three principal uses which are described here are piling, fendering and decking.

Load bearing timber piling and cross bracing, constructed of large dimension

pieces, is widely employed in both fresh and salt water situations. The timber

species used for piling are in many instances greenheart, basralocus, kapur,

pitch pine and Douglas fir. The choice of species for such work will depend

pre-eminently on the lengths required. Timber firms specializing in this market

will supply up to 19.0 m long hewn timbers, or 18.0 m sawn, or longer lengths as

round piles. At the present time, lengths over 9.0 m are generally restricted to

greenheart, basralocus and Douglas fir, (or commercial hemlock (Hembal) if the

piling is to be of a temporary nature).

A much wider range of species could be employed if the problem of end jointing

could be overcome economically. The use of glue laminated timber is one

solution, but the finished product will cost more, and difficulties in drying and

glueing some of the timbers which would be selected for piling still have to be

overcome, The performance of laminated timber in the intertidal zone has been

questioned, but it has been shown that unpainted beams of approximately 75 mm square section of a medium density hardwood bonded with phenol formal-

dehyde and resorcinol adhesives showed only slight delamination in 10 years

exposure when half immersed in sea water.

In this country square timber piles are traditionally used. It has been calculated

that if round piles were employed, one-and-a-half times the load bearing capacity

of square piles of equivalent average cross sectional area could be achieved.

Torsional rigidity would be increased, wastage implicit in the squaring process

would be eliminated, twisting during driving would be less important, and

abrasion of sharp edges of square piles would be avoided. An inexpensive

method of head connection must be devised so that round piles may be fully

loaded. These have been developed to the satisfaction of American authorities,

but only for lightly loaded round piles.

12


7.0 m . *

75 mm x 225 mm Decking timbers 75 mm x 225 mm Kerbs 1140 mm

!-I 175 mm 2: 350 mm Bearers I

I \ 1 6

300 mm x 300 mm Transom

\ t -

9mm x 75mm

Galvanised

ms. straD

150mm x 300 mm I

Fender ’

4.5 m centres

> 150 mm % 300 mm +; 2 at 150mm X 300mm

--EG

2.5 m

300 mm x 300 mm I

Piles

4.5 m centres

~

_,’

I I 1 t

I

I I

4s

igure 5 ‘ypical jetty design

13


Figure 6

Cliff erosion, Norfolk

Figure 7 Sea defence groynes at Hayling Island

14


Figure 8

Groyned shingle and sand beach,

Lancing, Sussex

‘C

c

a

r i

Figure 9

A ‘dog-legged’ groyne and wave

screen, Lancing, Sussex

15


The function of a pile is to transmit a superimposed load or loads to the adjacent

soil, or to a hard underlying stratum such as rock. The supporting power of

piles is dependant upon many variable factors, including the over-all number,

arrangement and spacing in a given area, and must also take into account how

the load is sustained.

The determination of the load bearing capacity is assessed according to one or

other of the following classifrcations:-

((a) Where the pile tip rests on a solid stratum by which the load is carried, and

there is little or no friction along its sides, or

(b) Where the pile receives practically all its support from earth friction along

its sides.

Piles in classification (a), are considered as columns and designed accordingly,

and those in classification (b), must also be considered as columns, but the

proportion of their length which extends above the soil must be considered in

the light of whether or not this unsupported length can be braced.

Piling is generally subjected to impact and static loading; these may be briefly

described as follows:-

(a) Impact during driving. High velocity of the driving ram at the instant of

impact may cause brooming, splintering and splitting of timber piles. The use of

a heavy ram using a short stroke is desirable since a drop of 7.6 m for example,

results in two-and-a-half times the velocity of a drop of 1.2 m.

(b) Impact in service. This may be caused by floating objects or boats being

slapped against a structure by wind or wave action, or by an error of judgement

resulting in a vessel colliding with the structure.

(c) Static stresses. These include bending stresses due to eccentricity of

loading; bending stresses due to curvature of the pile itself; bending stresses

due to lateral forces; tensile stresses due to uplift and rebound in driving, and

compressive stresses due to service loading.

Lateral forces may be exerted in a variety of ways, They can occur by wind action forcing vessels laterally against a structure (short of impact), or by wind action

alone, or through pressure of boats or barges.

The properties desirable in piles include sufficient strength and straightness to

withstand driving and to carry the weight of structures built on them. The

reduction in strength of a timber pile resulting from slight curvature of the

timber, eccentric loading, or any other condition that will result in combined

bending and compression is not so great as might be expected. Tests have

shown that a timber when subjected to combined bending and compression,

develops a higher stress at both the elastic limit and maximum load than when

subjected to compression only. This does not imply that curvature and eccentri-

city should be without restriction, but it should relieve anxiety as to the influence

of curvature that might be present in timber piling.

Fender piles Direct collision of vessels with dockside installations may give rise to heavy stresses in reinforced concrete and steel structures. As these materials have

low resilience, protection is usually provided by other materials which are

capable of cushioning and diminishing the intensity of the blow. Fender piles

and accessories such as cork and rope fender coils and floating fenders are of

great value in reducing the maximum pressure on dock structures. There is

much diversity of practice in the use of fender piles. Some are single piles

connected to a jetty at the head, others are single in width but bolted two or

three deep, resting at the head against a rope coil, and others again are built

up from 8 piles, 4 abreast and 2 deep, bolted and braced together.

Timber fender piles are usually driven into the sea bed a short distance (750 mm)

in front of the jetty and freely anchored thereto at deck level. Between the head

of the pile and the structure, timber chocks, rubber buffers, springs or coiled

ropes are placed to decrease the magnitude of the blow on the jetty from a ship

coming alongside. Good results were reported when 350 mm x 350 mm square

piles were installed in 6.0 m of water. spaced at 2.25 m-3.0 m centres and driven

3.6 m-4.5 m in compact soil, sandy clay, sand or gravel. Single pile fenders,

driven at an outward rake and the head drawn in towards the main structure and

anchored, form an initially stressed and bowed pile, with the convex surface

towards the vessel, On impact it acts like a spring. In one example of stressed

16


Figure 10

Land ties of home grown oak, Worthing, Sussex

Figure 11

Groyne with land ties on both sides near Cromer, Norfolk


Figure 72 Mobbs permeable groyne

fender piling, 300 mm x 300 mm piles at 1.5 m centres, with the heads connected

with stout walings, were used to protect a 0.80 kilometre long jetty, and gave

excellent service.

The species of timber used for fendering and fender piling are similar to those

recorded for piling. To protect the face of fender piles and to take the minor

buffeting, it is usual to fit timber rubbing pieces about 150 mm thick to the pile

face.

Decking Timber is often used for decking of wharfs, jetties and floating pontoons.

Drainage of such areas may be achieved by spacing the boards. The commonest

sizes employed are 25 mm-75 mm x 125 mm in section. There may be a hazard

from decay in all parts of jetties above the water level. Design of such structures

should take into account that horizontal surfaces may hold water and should

therefore be shaped to allow water to run off. Water may also lodge in joints,

and in these areas precautions should be taken to prevent decay by the use of

naturally durable or preservative-treated timber.

Timbers vary in their wear resistance to pedestrian and other traffic when

employed as decking, and the use of species such as Douglas fir, Western

hemlock, Baltic redwood and dahoma is best confined to areas of light traffic.

Pitch pine, dark red meranti, keruing, kapur, opepe, jarrah and karri, for example,

have sufficient resistance to wear to recommend their general use for decking,

except where resistance to heavy pedestrian traffic (i.e., of the order of 2000

people per day in well-defined traffic lanes), severe trucking, and resilience to

impact loads is required, when oak, danta, belian, greenheart and okan, amongst others would be preferred.

Rubbing pieces A wide variety of timbers are successfully utilized as rubbing pieces or fenders

on solid pier walls and jetties. The chief requirements are resilience, compress-

ibility and resistance to splitting on impact. As these rubbing pieces can usually

be built up to any required length by scarfing, or butt jointing using conventional

jointing methods, or by glueing, size is not such an all important factor as with

piling. Lengths required run up to 9.0 m, with sections from 75 mm x 300 mm,

150 mm x 200 mm and up to 300 mm x 300 mm. Resistance to splitting on

impact or abrasion can often be correlated with wild or interlocked grain, and the

widespread use of elm for rubbing pieces can be related to the variation in grain

direction in commercial timber of this species. For similar reasons, tropical

hardwoods with interlocked grain are also widely used.

Thefloating timber boom placed alongside the quay wall acts in the same general

way as a rubbing piece, and has similar requirements. The timber must of course

float. In the Port of London such booms are constructed to three main lengths, 18.0 m, 14.0 m and 9.0 m, and successful trials have been carried out using

600 mm x 600 mm Douglas fir baulks glued together in sets of three, to provide

the required widths. Alternatively, these booms would be bolted or spiked.

18


The species used for rubbing pieces include elm, Douglas fir, pitch pine, oak,

arrah, opepe, ekki and okan. Reference to Table II will give indication of the

wide selection of durable timbers that could be used.

Lock gates Timber has been utilized traditionally for lock gate construction, and today on

inland waterways is still in wide use. Ability to withstand shock loads, high

strength/weight ratio, comparatively low cost and ease of in situ repair are the

main predisposing factors.

Sizes required vary according to lock size. Typical requirements are given here

for a pair of gates on the Sheffield and South Yorkshire canal.

Head (mitre) posts and heel posts-greenheart-7.6 m x 400 mm x 400 mm

Fenders and walkways-wych elm -4.5 m x 50 mm X 200 mm

Sills-Dutch elm -4.0 m x 300 mm ;< 380 mm

Pitch pine planking -4.2 m x 75 mm x 250 mm

Gate members-oak -2.7 m-5.1 m, 200 mm x’ 250 mm

to 380 mm x 380 mm

Species commonly employed on inland waterways include oak, pitch pine,

Dutch and wych elm, or greenheart where extra strength, abrasion resistance or

long lengths are required. Again, reference to Table II will indicate the wide

range of timbers that could be used.

In hand-operated locks, which still constitute the majority on inland waterways,

balance beams are required for opening and closing the gates. These are

traditionally constructed of oak. Large sizes are required, e.g., 8.0 m long, 450

mm x 450 mm tapering to 380 mm x 380 mm. Where difficulty is experienced

in obtaining the size required, alternative timbers could be used, or they could

be fabricated from laminated timber.

The life expectancy of a lock gate is approximately 30 years, but this will vary

according to the amount of traffic and mechanical damage sustained. Where

locks are mechanized, balance beams are not required, but on some canals it is

desirable to have a mechanical system which can be disconnected, and manual

operation carried out at certain times. In this case, a balance beam, which can

be tied into the mechanical control is necessary.

The design of lock gates has scarcely varied since the canals were first built

some 150 years ago. Gates were essentially the work of craftsmen, skilled

carpenters producing well fitted mortise and tenon joints reinforced on either

side by hand wrought iron plates bolted through. These were of very stout and

durable construction, capable of hard usage and absorbing the impact of laden

craft. Latterly the volume of commercial traffic on some canals has lessened or

ceased altogether, but there has been an increase in pleasure craft. Under these

circumstances more simplified construction methods have been tried out to

cater for the changing usage. Gates constructed from timber in smaller sizes using simple machine cut mortise and tenon joints which are glued and cramped

together with spikes, have produced a strong form of construction and have

performed well over an initial five-year period.

Ancillary uses of timber at locks on inland waterways include stop logs, which

may be up to 7.6 m long and 300 mm in section. These are used to close off

locks during periods of maintenance, and timber strutting is used to support

the walls of emptied locks. Rubbing pieces and kerbs on lock walls, fendering on

lock gates, breakwaters, walkways and hand rails are other uses.

Larger lock gates may be constructed of timber or steel. In the latter case timber

is selected for the heel and mitre posts, and timber waling and fendering is

widely employed for protection. Mitre and heel posts on lock gates may be up

to 18 m long and cut from logs up to 685 mm diameter. Another more usual

specification is for mitre posts 250 mm x 750 mm x 15 m long and heel posts of

similar length 750 mm wide, cut half round with a 400 mm radius. The Port of

London Authority have successfully carried out repairs to such members by

in situ glueing. Abrasion can be severe even on dense timbers, and recently

trials have been instituted on stainless steel inserts and composition materials

for the top and bottom 1.0 m sections of heel posts.

19


Fendering on steel lock gates is mounted on 300 mm x 300 mm-450 mm

‘/’ 300 mm waling, often constructed from elm. On this waling close-boarded

fendering 150 mm x 300 mm in section is fixed, pitch pine often being employed.

Sluice doors in locks may vary greatly in size from 1.8 m-4.2 m square, and a

wide variety of species are used.

20


Figure 13 Greenheart and basralocus

piles at the car ferry terminal Dover. With acknowledgements

to Dover Harbour Board

Figure 14 Mooring piles, Thames Conservancy

Figure 15 Lead in jetty, Port of London Authority


Figure 16

Preservative treated

softwood decking, Empire Jetty Wharf, Millwall

FigL rre 17 Jarr .ah decking on the

Roy al Pier, Southampton. Ack nowldegements to the sou thampton Harbour Board

Figure 18

Hardwood decking, Shoreham Harbour


Figure 19

Jetty decking boards fixed with sherardized

screws driven into pre

holes with a pneumatil

Acknowledgements to Geo. Wimpey & Co. Ll

Figure 20

Floating softwood timb boom or dummy.

Acknowledgements to British Transport Corn1

coach

-bored

c wrench.

:d.

Ner

the

mission

Figure 21 Fenders at Poole Harbour

23


Figure 22 Mechanized lock gate. The mechanical control is

fixed to the balance beam and it can be detached for manual operation. North East Division

British Waterways

Figure 23 Lock gate manufacture,

North East Division British Waterways

24


Figure 24 Four gates of the Gladstone Hornby Lock, Liverpool,

constructed from greenheart. Each gate is 15.0 m J 13.5 m high

Figure 25 Lock gates, North East Division

British Waterways


Figure 26

Timber barrier

protecting a canal bridge

from floating debris,

North East Division British Waterways

Figure 27

A butt joint in a hewn hardwood pile. The steel plates are coach screwed to all four

sides and the overlapping corners of the plates are

arc-welded to complete the box. Acknowledgements to

Geo. Wimpey & Co. Ltd

26


Figure 25

Joints constructed from steel plates and rolled steel

channel sections in conjunction

with coach screws and shear

plate connectors.

Acknowledgements to

Geo. Wimpey & Co. Ltd.

Figure 29

Effects of ‘spill-over’ wear

an a groyne. Note wear on piles above planking and wear on waling on sea side of waling-pile junction

27


Marinas and yacht havens

The growth of recreational boating stimulated a demand for specialized facilities

designed to provide safe and convenient mooring for pleasure craft. These

commonly range from small estuary sailing and inshore cruisers to luxury yachts up to 20 m but boats of whatever size, usually represent important investments

to their owners, and the need to care for them is apparent. In consequence, the

design and construction of marinas and yacht havens has developed into a

highly specialized field.

The usual requirements of a marina is that it has an adequate entrance

channel and turning area, and an attractive, yet protective breakwater, cat-

walks and mooring facilities, and a boat launch and retrieval system. The

engineering of these requirements has become increasingly complex because

of the special nature of building in and around salt or fresh water, and calls for

consideration of forces other than the normal dead and live load stresses.

Primary among these forces are those created by the movement of the water

itself; currents, tides, waves and wakes. The material used in such constructions

must be strong enough to permanently withstand these pressures, and yet yield

a little, while at the same time resisting the deterioration due to water.

The material used must also be able to resist the deteriorating effects of decay,

marine borers, sand abrasion, and of being alternatively wet and dry. Depending

on tides, currents and waves, many of the structures may be completely dry and

exposed to the sun, one hour, and totally submerged the next, the alternating

wetting and drying occurring several times a day.

Experience has shown that the most reliable building material for marinas is

wood, either of a naturally durable species, or of a suitable species of relatively

low natural durability impregnated under pressure with preservative, used in

conjunction with galvanized steel frames.

Two of the most critical structures are the bulkheads and breakwaters. The

bulkhead wall, since it determines the shape of the marina, allows the shoreline

to be designed aesthetically. thus complementing the overall layout, and at the

same time providing close-in deep water.

The bulkhead wall can be built of wood, concrete or steel, but wood is recom-

mended because of its absorption capacity, length of life, and reasonable cost.

As a point of possible contact between the pleasure craft and the marina

structure, a wooden bulkhead wall with a timber fender system provides extra

protection to the boats. The wooden sheet pile bulkhead has been found to be

most desirable and economical.

The function of the breakwater is to disrupt or break up the currents and waves

and prevent them from reaching the marina mooring area, thereby ensuring the

craft will be protected from surface water movement and lie relatively stable in

the water. The breakwater must also be arranged to accommodate a well located

and adequate channel, and vital turning area, and becomes a permanent, visible,

and controlling element of the marina.

The operational areas of the marina are the piers and catwalks, which may be

fixed orfloating, but often combine the two methods. Piers and catwalks perform

dual functions of providing berths or slips for the craft and easy access to them.

The loads these structures carry are fairly light, and they need be only of mod-

erate strength.

A fixed pier, as the name implies, is fastened to, or supported by piles driven

into the underlying soil. Because of their contact with water, these piles should

be of naturally durable timber, or of moderately durable timber heavily impreg-

nated with preservative.

Main piers are generally 2.5 metres in width, although this is sometimes reduced

to about 1.8 metres for economical reasons. Piers used for fueling or supporting

commercial facilities are frequently as much as 3.6 metres wide. Catwalks can

28


Figure 30

Typical marina layout at Poole. Acknowledgements to Savack Service Ltd

Figure 31

Marina main and finger walkways. Keruing decking on elm rubbing Wakes. Acknowledgements to Savack Service

Ltd

29


be of various shapes and sizes; often they are 1.0 metre wide where they connect

to main piers.

Floating piers can be the same width as fixed piers, but they are often of stan-

dard units hinged together or on rubberflex mountings to prevent damage by

water fluctuations. Floating catwalks are of the same lengths as fixed types,

but are usually of greater width to present more stability.

Floating piers and catwalks are normally constructed to ffoat from 450 mm to

600 mm above the water surface when not loaded. They are usually guided by

wood piles except in very deep water where anchor cables and counter weights

are used. Floating structures are connected to fixed ones, or to the shore by

hinged ramps.

Flotation systems normally employ timber on galvanized steel frames supported

on glass reinforced plastics for pontoon construction. Walkways can represent

a danger zone to marina users because of slipperiness when wet, but the possi-

bility of falls is greatly lessened by the use of timber decking, and round or

square wooden guard rails. Timber used for decking should preferably be

unplaned, but it must be well sawn, without undue variations in thickness. A

slip resistant surface is further promoted by using a species possessing only a

medium resistance to wear.

There is a preference for brownish coloured woods for decking, generally

because light coloured woods reflect sun glare, but all woods will bleach in time

and become discoloured when exposed to light, and the action of dust and sand

carried by winds, continual variation in moisture content brought by changes

in the weather, etc. At the present time, one of the preferred species for decking

is keruing, which apart from its general suitability, tends to exude tiny globules

of resin which add to its relatively slip resistant surface, but there are many

suitable species including iroko, teak, dark red meranti, oak, idigbo, jarrah and

karri among the hardwoods, and edge grain Douglas fir, treated under pressure

with preservative, that can be used.

Bolt heads and nuts must be recessed into the surface of marina decking so as

to avoid a hazard both to people and boats, and in the same way, timber used

for decking must be free from large knots which might eventually protrude

beyond the surface as this becomes roughened with wear. This is not a problem

with the general run of hardwoods, but the lower commercial grades of oak, as

an example, or of softwoods, intended for decking after preservative treatment,

require careful selection.

30


Joint construction

Various types of jointing have been used for marine timber structures, to ensure

that the components act together to resist applied loads. The large sections

employed often carry substantial working loads and heavy mechanical connec-

tors are required. Many joints will connect members in two planes. This means

that the systems which have been developed differ in some respects from those

used for normal timber construction in buildings and a brief description of their

characteristics follows.

Bolts and

‘Oath SCreWS

Mild steel bolts and coach screws have been used for many years and the safe

load values for the diameters generally employed are known for many species.

(See Bibliography).

The conditions of service must be considered when working loads are estimated.

High moisture content of the timber, loading other than parallel to the grain and

multiple bolt joints, will reduce the allowable load per bolt. However, short

duration loading which is frequently encountered in marine construction may

permit increases in safe loads. Bolts and screws can cause splitting of the

timber under load. Recommendations for correct spacing are available.

The size of a bolt or screw in relation to the dimension of the supported member

is an important consideration. Suitable sizes are as follows:-

Split ring connections and shear plates

Nails and spikes

Steel plates

Joint form (1) Pin join ted

Joint form (2) Rigid joints

Timber thickness (mm) 75 150 1 225 300

Bolt diameter (mm) 16-22 22-32 ( 32-44 44-63

Preloading with high tensile steel bolts and threaded rods has also been suc-

cessfully employed.

Working loads and information on the use of these connections and plates are

available for many timber species. (See Bibliography). Both split rings and shear

plates are recessed into the timber members and increase the effective bearing

area.

Planking both in groynes and decking on jetties is often fixed with nails or

spikes. Various sizes and shapes can be used. Square twisted or ring shanked

nails may be more economic than the traditional spikes. Many hardwoods will

need preboring to approximately three quarters of the nail size to prevent

splitting. Nails cannot be removed as easily as screws, and screws are more

suitable when resistance to direct tension is required.

Mild steel side plates fixed with bolts or coach screws have been used for joints

in jetties with large timber members. Shear plates can be used to assist this

form of connection. The side plates can be fabricated to receive fixings from

members in more than one plane and can be so shaped that the load transfer

is by direct bearing of linked plates. Fig. (A) shows such a pinned joint having

members in two planes and illustrates one use of shaped plates. Load transfer

by direct bearing using linked plates in a mixed timber and steel structure is

illustrated in Fig. (B). Coach screws were provided to facilitate erection and

carry a light shear loading.

In a framed structure, the members will be struts or ties free to rotate at their

ends. With this form of construction, it is important that the axes should meet

at one single intersection point. Sometimes, this is not possible because of the

size of the members but care must be taken to keep the divergence of the centre

lines from the intersection point to a minimum. The freedom of rotation of

members at a joint is impeded by multiple bolts but provided eccentricity is

limited, the stiffness is of no consequence. Fig. (A) shows a joint in this form.

Frequently structures have rigid joints in which both axial forces and bending

moments are transferred producing a portal frame. The joint form is usually

produced using steel plates bearing on the surface of the timber, the erection

procedure being planned to eliminate the effect of minor sawing errors and

31


Figure (A)

Use of linked side plates cut from standard rolled steel sections in a mixed timber

and steel construction

Mild steel

galvanised joint plates

Deck planking Capping beam Deck joist

bolts

ELEVATION

Joist hanger from

Id steel strip welded

Coach screws

I ,-_J

PLAN (Deck omitted)

produce a rigid structure. Fig. (B) shows a rigid connection between a steel

frame and a timber pile.

A stiff or rigid joint connection will be readily obtained when a concrete deck

slab is cast on to timber piles. Provided the pile is encased for some 26 times

its least lateral dimension, deck bending moments are transmitted to the pile through the bearing of the concrete on the timber. As the concrete is cast in

place, discrepancies in size or shape of the timber are eliminated and thus

round piling can be used to advantage.

32


Pinned butt timber joint using steel plates with

members in two planes

--

-_

Mild steel angle bracket welded to rolled steel joist

with fillet weld and root wetd. Straps of mild steel fixed

to pile with coach screws and welded to angle brackets

after fixing cross head beams with coach screws

Timber pile SECTION a/a

RIGID CONNECTION

Steel framing and timber piles

Weld before fixing

a -f-

-

Pile inside

t

-

PLAN ’ Weld

J after fixing

Should a concrete deck-to-timber pile joint be required having limited stiffness

this is provided by embedding a short length of pile head containing steel

dowels of a suitable size. The dowels also serve to resist extraction.

33


Environmental hazards

There are two main types of hazard to which timber may be exposed-mechanical

damage, including crushing and general wear and tear of timber fenders on

jetties and harbour walls, and abrasion which occurs on groynes on shingle

beaches. Biological hazard includes fungal decay of timber above the water

line and marine borer attack of timber below approximately the mid-tide level in

seawater situations. Wear resistance of timber species for decking is discussed

under ‘Decking’.

Mechanical damage Fenders, rubbing pieces,

The object of a fender on a harbour wall or any other dock structure is to resist

etc. the impact of a ship coming alongside and to protect the main structure and the

ship from being damaged by such an impact. It should also protect both ship

and structure from damage by wave action or tidal rise and fall whilst a ship is

alongside.

Traditionally timber has been chosen for fenders as it is very resilient and will

withstand shock loads better than most other constructional materials. The

species selected are very often chosen because of their resistance to splitting

at the time of impact. The use of elm is an example. A disadvantage in the use

of elm is its low resistance to biological hazard and moderate resistance to

wood preservatives applied by pressure. A surface coating of preservative

might be easily rubbed off or splits might develop which at the lower end of the

tidal range might allow marine borer attack to occur under the treated skin.

In marine construction, however, if the life expectancy of timber fenders may

not be more than 10 years, it is possible that failures of treatment in this way

would not be of great importance.

Interlocked grain in tropical hardwoods, such as ekki, jarrah, opepe and okan,

which are sufficiently durable to be used in the untreated state, makes these

timbers suitable for rubbing pieces.

Sea defence groynes Abrasion of sea defence groynes may be important on shingle beaches. It has

been shown on beaches in Sussex, where a shingle bank lies on sand and is

confined to a zone above the lower third of the tidal range, that abrasion of

vertical piling can be considerable. However, timber certainly withstands such

wear better than concrete or steel. Scour and spillover are the principal causes

of abrasion and loss of timber by abrasion on piles has been recorded as

between 100 mm and 180 mm diagonally from a corner over a period of six years.

Scour is caused by tidal wave borne shingle wearing the planking. Spillover is

the result of accumulation of beach material at the down-stream end of the

groyne compartment which chiefly causes pile wear. The resistance of timber

to such wear seems to increase with increasing density, and generally dense hardwoods over 960 kg/m3 would be preferred. However, it appears that soft-

woods with well-marked dense latewood zones in the growth ring such as

Douglas fir and pitch pine will perform as well as the heavy hardwoods. Preser-

vative treatment of timber in areas where abrasion occurs is of no value as the

protected surface layers soon become worn away. However, this is not likely

to be important as marine borer attack of timber could not occur or survive on beaches at the positions where abrasion occurs, and the presence of salt water

will preclude conventional timber decay. Abrasion is greatest on piles and

occurs to a much lesser degree on planking and whaling. The effects of wear on

piling can be spread by adding an extra layer of planking, as in normal sea

defence practice.

Biological attack This can be best considered separately under the two main types of environ-

ment covered in this booklet, namely fresh water and salt water.

Fresh water The most important biological hazard to timber in fresh water situations is

fungal decay. If timber is used externally, moisture content will rise and decay is certain to follow unless naturally durable or preservative-treated timber is

employed. This statement must be qualified by the consideration that timber

permanently and completely immersed in fresh water will not decay as there is

35


insufficient oxygen available for decay fungi to carry out the process of break-

down. Admittedly soft rot decay occurs on timber completely immersed in

fresh water, but its rate of progress is so slow that on timber of any dimension,

ie., over 75 mm ‘X 75 mm, its effect is negligible. There are numerous examples

of the long life of timber under fresh water-the excellent condition of the elm

piles withdrawn at the time of the construction of the new Waterloo Bridge

after over 100 years in use illustrates this point. At and above the water line,

however, conditions may be very suitable for decay and to avoid this and to

provide a timber structure or component with a long life it is necessary to

specify preservation, or naturally durable timber. It should also be realised that

timber embedded in concrete, brick or other porous materials will also achieve

high moisture contents and decay may follow.

Salf wafer Salt water can act as a timber preservative and heavy salt deposition in wood is

a protection against fungal decay. However, salt deposition on and in wood may

not be permanent and there will be situations when the effect of rain and fresh

water is to remove salt deposits from such timber faster than they accumulate.

This means that timber removed or away from the direct influence of salt water

which attains a high moisture content, i.e., on horizontal surfaces or at joints,

is liable to decay and precautions must be taken if this decay is to be prevented.

The greatest biological hazard to timber permanently immersed in the sea is

the activity of marine borers.

Marine borers Animals which attack and destroy timber in the sea are grouped into two types,

Molluscs, related to the oyster and Crustaceans, related to lobsters. In British

and other temperate waters, only two types of animal are of economic sig-

nificance, the crustacean Limnoria (the gribble) and the mollusc Teredo (the

shipworm).

Another crustacean Chelura has often been reported as being capable of

destroying timber and is commonly found in timber already attacked by Limnoria.

It has recently been shown that Chelura is not capable of burrowing rapidly

into timber in the absence of Limnoria and need not, therefore, be considered

as a marine timber pest of economic importance.

The shipworm The popular name of this animal arises from the white elongated body of the (Teredo sp. et. al.) adult. It is technically incorrect as it is not a worm, neither is its occurrence

confined to ships. It is difficult to give a figure for the maximum size of the

animal because this will depend on the size of the timber attacked and on the

number of individuals present in the same piece. Specimens 88 mm long with a

maximum tube diameter of nearly 8 mm have been found in test blocks of

susceptible timbers exposed for only five months. Specimens have been

recorded of 500 mm length in America and 600 mm for Bankia, a related genus.

The mature adult releases small microscopic larvae in vast numbers which

after free existence of up to one month duration, during which time dispersion

occurs, settle on timber and commence boring after metamorphosis. As the

larva is very small, the point of entry into the timber is rarely more than 0.5 mm

diameter and there is little external evidence of the interior condition of the

timber. As the burrow is enlarged, usually along the grain, the diameter of the

tunnel increases, the body length increases with burrow length and ultimately

burrows may penetrate deeply in timber of large dimension. An adult is, of

course, unable to emerge from its burrow, and so attack of fresh timber only

occurs through the dispersion of the free-living larval stage.

The mature animal has two shells at the ‘head’ or blind end of the burrow and it

is the continual grinding movement of these two shells which enlarges the

burrow. Shortly behind the head, a white calcareous deposit is laid down as a

burrow lining which is continuous for the rest of the burrow. At the ‘tail’ end,

two pallets are found, whose function is to seal off the burrow during conditions

unfavourable to the animal. Under favourable conditions, two tubes or siphons,

scarcely visible to the naked eye, protrude through the entry hole. These siphons

are the only direct contact retained with the sea. A circulation of water is drawn

in through the inhalent siphon and is passed over the gills where small plank-

tonic animals and detritus are collected and where oxygen is absorbed for

respiration. Waste products, reproductive spawn and larvae are carried by this

circulation to the exhalant siphon and thence to the sea.

36


Whilst Teredo and other similar marine wood-boring animals can utilise plankton

and detritus as a food source there is now no doubt that they are also capable of

digesting wood particles which are produced by the grinding action of the

shells, and that cellulose can be utilized as a food source.

When timber in the tidal range is attacked, the burrow will be closed by the

pallets when the burrow entrance is not covered by the sea. Thus, attack of

timber in the lower part of the tidal range can occur, but is unlikely to extend

above the mid-tide level.

Shipworms are confined to marine and estuary areas and are unable to survive

in fresh water. Their distribution in British waters seems to be mainly confined

to England and Wales. Their occurrence is sporadic and some areas remain

virtually free from Teredo. Attack may occur at all depths below about the mid-

to low-tide level, on unprotected coastal timber structures.

rhe ~~~~~~~ These animals are small crustaceans resembling woodlice in appearance. They

(Limnoria sp.) are usually about 3.2 mm in length and their burrows in timber are less than

2.5 mm in diameter. They rarely penetrate into timber more than 12.5 mm.

Extensive attack by Limnoria so weakens the surface of the wood that eventually,

the severely attacked surface gets wasted and eroded away. The attack occurs

at all depths below mid-tide level on coastal timber structures, but it often

appears to be greatest in the tidal zone as wave action increases the effect of

the water erosion.

Eggs develop in a brood pouch of the female. They are retained during develop-

ment and the young are released direct into the parent burrow and they soon

start boring on their own. During the warmer summer months large numbers of

mature animals migrate to fresh timber. The dispersion is largely achieved by

water movement but active swimming can occur for short periods. If an animal

alights on a suitable piece of timber, active burrowing commences and the whole

body may be enclosed in its burrow within three days.

It has been shown that Limnoria is capable of breaking down cellulose thus using

wood as a food source. The widespread occurrence of marine soft rot fungi on

wood, although unlikely to be of practical importance alone, will facilitate the

attack of timber by limnoria.

Prevention of It is perfectly possible to overcome the effects of biological deterioration of

biological deterioration timber in the sea and in fresh water. In fresh water situations, where decay is

the major hazard, the use of wood preservatives or naturally durable timber is

essential. In the sea, prevention of attack can be achieved by using a more

restricted list of durable hardwoods, wood preservatives or by the use of imper-

meable sheeting of various types.

Natural durability- In this section natural durability is assumed to refer to resistance to decay. As Fungal decay a broad generalization it can be said that heartwood of dense, dark-coloured

timbers tend to be more resistant to decay than light pale-coloured species. The

sapwood of nearly all species is readily decayed by fungi. Undoubtedly there are

variations in natural durability in heartwood timber of the same species which

have grown under different environmental conditions, and in some timbers the

core may be less durable than the outer zones. Despite these variations, natur-

ally durable timber can be utilized successfully under conditions where perish-

able species would rapidly decay.

The natural durability of timber has been assessed by carrying out graveyard

tests. Specimens of heartwood 600 mm long and 50 mm x 50 mm in section are

placed in the ground to a depth of 450 mm and the time to failure by decay noted.

From this type of test it is possible to compare the natural durability of different

timbers, and to give a life expectancy in ground contact for 50 mm x 50 mm

heartwood timber. It seems reasonable to presume that similar ‘lifes’ can be

expected from timber exposed to fungal decay in other situations. The following

classification of durability has been adopted in this country by the Building

Research Establishment, Princes Risborough Laboratory.

37


Figure 32

X-ray radiograph of a test sample of Baltic redwood, showing severe Teredo attack

Figure 33

Teredo damage in a test sample.

The cut surface indicates interior damage. The small ‘entry holes’ of Teredo can be seen on the

face of the sample

Figure 34

Diagrammatic representation

of Teredo life cycle A Young larvae B-C Older larvae D-G Stages in burrowing

38


Figure 35

Limnoria in its timber burrow (approx. x 10)

Figure 36

‘Erosion’ on a softwood

fender as a result of

Limnoria attack

Figure 37

Limnoria attack of timber, The main ‘parent’ burrows

and subsidiary boring of the in situ hatched brood can be distinguished


Natural durability- The durability classification of the commoner species of timber likely to be used Marine borer attack in marine and fresh water situations is found in Table II

Wood preservation

Classification Life Expectancy in

Ground Contact (years)

Perishable

Non-durable

Mod. durable

Durable

Very durable

up to 5

5-l 0.

IO-15

15-25

over 25

It is accepted that changing the cross sectional area of timber can influence the

life expectancy. Thus a specimen 100 mm x 100 mm could be expected to have

about double the life of a piece 50 x 50 mm. Similarly, a 150 mm I\ 150 mm

section of a very durable timber heartwood may be expected to have a life of at

least 75 years if fungal decay is the only hazard.

The resistance of timber to marine borer attack does not exactly parallel the

resistance to decay; no timber is known to be entirely resistant to marine borers,

and only a few exhibit the high resistance required. However, the service life of

timber is often influenced by local conditions and the particular species of

marine borers present, and of course, resistance of timbers to marine boring

animals is important only when the timber is used in salt or brackish waters.

Timbers that show a high resistance to Teredo in some waters are sometimes

far less resistant in others. Simarly, timbers may vary in their resistance between

salt and brackish waters. These differences are considered to be the result of

different types and species of marine borers from one place to another.

Exposure trials suggest that some of the species listed in Table I have this

natural durability, and will provide a satisfactory life when exposed to marine

borer attack.

The durabilities quoted in Table II are to be interpreted as follows:-

Very durable Suitable under conditions of heavy attack by Teredo and

Limnoria, and should provide at least 20 years of life.

Moderately durable Suitable under conditions of moderate attack, mainly

Limnoria.

Non durable Suitable for only short service life.

Table I gives a guide to the potential use of certain other timbers not listed in

Table II. The selection is based upon a particular timber’s performance in

TRADA exposure trials carried out at Shoreham during the sixteen year period from 1950 to 1966, together with other species which performed well in exposure

trials carried out at Wrightsville, North Carolina from 1949 to 1955 (See Biblio-

graphy). Also identified in the table are some timbers rated by reputation rather

than by research. Further research may well change the ratings, but they can

all be considered as being at least moderately durable in the use situations

suggested. Timbers listed under (a), can of course be used for the same pur-

poses as those under(b). The use of preservative-treated timber will greatly increase the life of non-

durable timber in both fresh water and marine construction. Undoubtedly the

fresh water situation is a less severe environment and consequently a wider

range of preservative methods are suitable than for marine work.

For all timber uses referred to in this booklet the employment of preservative

treatments applied under pressure is essential. There are British Standard

specifications covering the use and recommended retentions of three types of

preservatives currently available, i.e. copper/chrome, BS3452: 1962, copper/

chrome/arsenate, BS4072: 1966, and coal tar creosote, BS913: 1954. Creosote

has been used for many years and impressive service record data is available.

It is important to realize that timber must be seasoned to a moisture content of

20-25%, and all shaping and cutting carried out prior to treatment.

40


Table I Timbers additional to Table II but potentially suitable for

piling and underwater construction

Trade name Botanical name

(a) Teredo infested waters

African padauk” Pterocarpus soyauxii

Afrormosia* Afrormosia elata

Afzelia Afzelia spp.

Albizia” Albizia zygia

Bawang hutan* Scorodocarpus borneensis

Determa Ocotea rubra

Essia” Combretodendron africanurn

Freijo Cordia goeldiana

Idigbo” Terminalia ivorensis

Kau ta-? Licania spp.

Kautaballi+ Licania spp.

Keledang” Artocarpus spp.

Makore* Tieghemella heckelji

Maris hl_ Licania spp.

Mecrusse” Androstachys johnsonii

Muhuhu” Brachylaena hutchinsii

Muninga* Pterocarpus angolensis

Resak” Cotylelobium flavum

Suradan Hyeronima laxiflora

Wacapout Vouacapoua americana

(b) Non Teredo waters

Afina” Strombosia pustulata

Agba* Gossweilerodendron balsamiferum

Angelin Andira spp.

Ayan” Distemonanthus benthamianus

Courbaril Hymenaea courbaril

G uarea” Guarea spp.

Keranji” Dialum spp.

Kopie Goupia glabra

Merpau” Swintonia spp.

Utile* Entandrophragma utile

Origin

W. Africa

W. Africa

E. & W. Africa

W. Africa

Sabah

Guyana W. Africa

Brazil

W. Africa

Guyana

Guyana

Malaya

W. Africa

Guyana

E. Africa

E. Africa

E. Africa

Sarawak

Guyana

Brazil & Surinam

W. Africa

W. Africa

Guyana

W. Africa

Guyana & Brazil

W. Africa

Malaya

Guyana & Surinam

Malaya

W. Africa

Note. Timbers marked with an asterisk figured in TRADA exposure trials at

Shoreham. Those marked with t were included in exposure trials at

Wrightsville N.C., while those not marked possess a reputation for

suitability.

Timber varies greatly in its ability to absorb preservatives. Almost all sapwood,

which is the area most likely to decay is permeable. The permeability of con-

structional timbers is given in Table II. The incising of timber which is otherwise

difficult to treat has much to recommend it, if a long life is required in severe

environments.

Ofher methods of Many other methods of preventing marine borer attack of timber have been pro-

Preventing marinea;;;:; posed and used with varying degrees of success. One of the most effective

seems to be a plastic sheeting; a proprietary nylon/vinyl sheeting has proved effective in short-term trials. The major disadvantage of this method is that it

must be bonded to the timber and as this would have to be carried out on timber

of low moisture content, is more suitable for boats.

An attractive alternative is the use of plastic sheets of impermeable materials.

Polyvinyl chloride sheet is a common and relatively cheap example. It has been

suggested that these sheets can be wrapped around timber piling, both above

and below water level, but not above high-tide level, either initially before instal-

lation or as an eradicant of existing marine borer attack. It forms a protecting

layer which would increase the life of partially damaged piling. The material is

42


impermeable to oxygen, thus killing all animals in the wood. Clearly it could not

be used on fenders and in other situations where abrasion occurs, but should

prove suitable as a protection for the main supporting piling of a structure. So

far as is known, this type of protection has not been tried in U.K. waters.

It should be stressed that this method would be quite unsuitable for preventing

fungal decay and indeed in fresh water situations might actually encourage

decay above the water level.

42


Suitable timbers

Softwoods

Douglas fir

(Pseudotsuga menziesii)

HemlockWestern

(Tsuga heterophylla)

Larch European

(Lark decidua)

Pine, Pitch (American)

Pinus palustris

and P. elliotti

et al)

Pine,lPitch (Caribbean)

(Pinus caribaea)

This section is devoted to short notes on the species which are suitable for

constructional purposes in the sea and in fresh water. Data on strength pro-

perties, durability etc., on those species more commonly used, are presented in

Table II.

This tree occurs in Canada, mainly in British Columbia and in the Western U.S.A. It has also been planted in Europe and elsewhere. The heartwood is light red brown and clearly distinct from the lighter coloured sapwood. It is generally straight grained and somewhat resinous. The timber screws and nails well with

only a small tendency to split. As Douglas fir is only moderately durable, it should

be pressure treated with preservative if used in an environment where biological

degrade can be expected and, as it is a resistant timber, incising should be considered. Large sizes are obtainable-up to 12.0 metres and 350 mm x 350 mm

generally from stock. It is employed for piling and fendering as well as for sea

defences and for decking, but should not be selected if heavy traffic is expected.

Edge grain stock, i.e., rift or quarter sawn is best for wear.

Western hemlock is a large tree which grows in Alaska, British Columbia, and

Western U.S.A. and has been planted in the U.K. The timber is straight grained,

pale brown in colour, and generally free from resin. It has comparable strength

properties to European redwood, with about the same weight. It does not work

as easily as redwood and has low natural durability, and is resistant to preser-

vative treatment. Consignments of hemlock may contain a percentage of balsam

fir (Abies spp) which is a timber of inferior strength properties. This is usually

shipped under the trade description hembal. Because of its low natural

durability and resistance to penetration with preservatives, it should only be

considered for temporary work in situations where risk from biological hazard

is high.

European larch has a natural distribution throughout Northern Europe, and has

been planted extensively in the U.K. The timber is straight grained, with a

resinous, moderately durable, red-brown heartwood, clearly differentiated from

the narrow, light coloured sapwood. It is one of the strongest, toughest and

heaviest softwoods On account of these properties, larch has been widely

employed in fresh water construction work as piling and planking, and as a

rubbing timber. It is not available in large sizes.

American pitch pine is typically harder and heavier than other commercial

species of pine (except for Caribbean pitch pine). The timber has well marked

growth rings, which give it a coarse-textured appearance. The heartwood is

red-brown, resinous, and well differentiated from the sapwood which is about

50 mm wide. The strength properties are similar to those of Douglas fir and, as

the heartwood is only moderately durable, preservation is recommended for

severe conditions of use. The timber is not as difficult to treat as Douglas fir,

but this will vary with the resin content. It is used for similar purposes, and many

authorities prefer it to Douglas fir. At the present time, supplies of American

pitch pine on the U.K. market are difficult.

The properties of this timber which occurs in Central America and the West

Indies, are similar to American pitch pine, but it is heavier, harder, and generally

stronger, and often more resinous. It is used for similar purposes, and should

receive preservative treatment in the same way. Honduras and Nicaragua supply

most of the pitch pine on the U.K. market at the moment, and this is easily

available in lengths up to 7.6 metres and 406 mm x 406 mm.

43


Pine Scats This extremely well known timber has a wide distribution in Europe and Asia.

(European redwood) It is used for a multiplicity of purposes and is available in many sizes up to

(Pinus sylvesfris) about 6.3 metres in length. It is widely employed as normal duty rubbing pieces,

sea defence construction, planking, decking, and many ancillary uses. Where

biological hazard is expected, preservative treatment should be employed. It is

not very resistant to wear or abrasion.

Hardwoods

Balau This is a typical Shorea species of the heavy type; known as balau in Malaya,

(Shorea spp) selangan batu in Sabah, and sal in India. The heartwood is yellowish brown in

colour, and is classified as durable. It is rather difficult to work, but is suitable

for heavy constructional purposes, bridging, sea defences, piling, etc.

Basralocus (Angelique) This tree occurs abundantly in Surinam, French Guiana, and North Brazil. It has

(Dicorynia guianensis) a rose coloured heartwood, which turns brown on exposure. This medium

(D. paraensis) density hardwood has exceptional durability and natural resistance to marine

borers. Difficulties may be experienced in working, owing to the presence of

silica. It is an admirable timber for marine piling and fenders, and rs obtainable

in long lengths and large sizes, as hewn.

Belian This species occurs in Sarawak, Sabah, and Indonesia. The sapwood is a

(Eusideroxylon zwageri) yellow colour distinct from the darker heartwood, which varies in colour from

yellow to reddish brown. This is a hard and heavy timber, with slightly inter-

locked grain, and possesses exceptional natural resistance to biological de-

grade. It is difficult to work because of its hardness, but is suitable for most

marine constructional purposes. Availability is limited at the present time.

Chengaf Chengal occurs in South East Asia, and is among the best naturally durable

(Ba/anocarpusheimjj) timbers in Malaya. It is a hard, to very heavy wood, with slightly interlocked

grain. The heartwood is light yellow-brown with a greenish tinge when freshly

sawn, darkening to rust red to purple-brown. Chengal is not difficult to work, but

there is a tendency for saws to gum up slightly. It is suitable for short piles for

sea defences and mooring, bridging, groynes, and marinas. Lengths up to 7.6

metres, and occasionally up to 9.0 metres, are obtainable, and sizes up to 300 mm

X 300 mm.

Dahoma This species occurs in East and West Africa. The yellow brown heartwood is

(Pipfadeniasfrurn surrounded by lighter coloured sapwood 50 mm or more wide. It is a medium

africanurn) density timber with broadly interlocked grain. Dahoma is weaker than oak in

shock resistance, but superior to oak in toughness, hardness, and resistance

to splitting. It has a relatively low resistance to wear, but is durable, and only

moderately resistant to preservative treatment. It is suitable for rubbing pieces

of limited life expectancy, or for sea defences on sandy beaches where marine

borer attack does not occur.

Danta The tree is abundant in West Africa. The timber is dark reddish brown with

(Nesogordonia narrowly interlocked grain, the lighter coloured sapwood being generally about

papaverifera) 50 mm wide. Danta works well, but may split when nailed. It is a hard wearing

timber, resistant to biological attack, and suitable for piling, sea defences,

decking, etc.

Ekki Ekki occurs in West Africa from Sierra Leone to Nigeria and the Cameroons.

(~~~hi,.~ a/afa) The heartwood is dark red to deep chocolate-brown in colour clearly differen-

tiated from the lighter coloured sapwood which is generally about 50 mm wide.

The grain is usually interlocked, and the texture coarse and uneven. It is out-

standing for its hardness, which makes working very difficult especially with

timber that has been held in stock for a long time. Ekki is extremely durable and

very suitable for piling, and other marine constructional work.

44


Elm Dutch elm has a wider distribution in the U.K. and is a tougher timber than

(Ulmushollandjca)(Dutch)

~U’mus~rocera~(English)

English elm, but otherwise, the strength properties of the two timbers do not

differ materially. Elm is used for piling and fender piling, rubbers, etc.

Elm Wych This species is distributed throughout Europe; in the United Kingdom it is

(Ulmusglabra) commonest in North and West England and South Scotland. It is appreciably

superior in mechanical properties to the Dutch and English elm, and has a

straight grain. Like the other elms it is non durable, and although resistant,

should always be treated with a preservative in situations where biological

degrade is expected. It is used for similar purposes to the other elms.

Greenheart This tree grows in Guyana. The olive green heartwood merges into the lighter

(Ocotea rodiaei) coloured sapwood which is usually about 50 mm wide. The timber has out-

standing strength and durability, but has a tendency to split and is therefore

generally used in large sections. Long lengths are possible, up to 22 metres or

more.

Ipe (Guayacan) The names vary according to the species, but the timbers of the Lapacho group

(Tabebuia spp) of the Tabebuias are all very similar. The colour of the wood is olive brown to

blackish, frequently with dark stripes, and occasionally oily looking. Ipe, Tabe-

buia guayacan, is shipped from Brazil, while Tabebuia serrotifolia produces the

groenhart of Surinam, not to be confused with true greenheart. The woods are

rather difficult to work, being hard, heavy, tough and strong, with interlocked

grain. The lapachol compound peculiar to these woods appears as a yellow

powder when the wood is sawn and dissolves in water giving a red stain, but

this leaches out quickly when the wood is exposed to wet conditions, Ipe is

highly durable and is used for beams, bearers, bracings and walings etc.

lroko This tree is widely distributed in East and West Africa. The timber is a medium (Chlorophora excelsa) weight hardwood with valuable technical qualities. The heartwood varies from

pale yellow-brown to dark chocolate brown, and the sapwood is pale in colour

and between 50 mm and 75 mm wide. The grain is typically interlocked, and the

heartwood is very durable. Its properties make it suitable for dock and sea

defence work, marina and other decking, and other forms of construction.

Jarrah This species occurs in South West Australia. The heartwood is dark red with

(Eucalypfus margin&a) a narrow band of lighter coloured sapwood. The grain may be interlocked, and

gum veins or pockets may occur. The timber is very dense and very durable, and

it has high strength properties, but may tend to split. Jarrah is very suitable for

marine constructional purposes for piles and rubbing pieces, beams and

bearers, and for pontoon decking and kerbs in marina construction. It is obtain-

able in lengths up to about 9.0 metres, and in sizes up to 350 mm x 350 mm.

Kakaralli Black Kakaralli occurs in Guyana, Surinam, and French Guiana. The heartwood is

(Manbarklak) reddish to greyish brown when freshly cut, turning a uniform deep brown colour (Eschweilera spp.) on exposure, not sharply defined from the lighter brown sapwood. It is a hard,

dense wood, very durable and extremely resistant to marine borer attack. It is

eminently suitable for all types of marine construction, but is used mainly for

short piling, groynes and jetties, sea defences, marinas and bridges,

Kapur This species occurs abundantly in Malaya and Sabah. The heartwood is tight

(Dryobalanops spp) red-brown clearly demarcated from the pale coloured sapwood. It is straight

grained, works moderately easily, has good strength properties, and screws and

nails well. Kapur is obtainable in lengths up to about 9.0 metres, and in sizes up

to 300 mm ;x: 300 mm.

Karri This species occurs in Western Aust, *‘ia. It is heavier than jarrah and lighter

(Eucalyptus diversicolor) in colour, and usually has a straighter ! ?in. Strength properties are high, but

it has only a moderate resistance to marirl borer attack, and for locations where

this is expected jarrah is to be preferred. h,rri is very suitable for jetties, piers,

wharves, docks, pontoon and landing decking, etc.

45


Kempas Kempas has a general distribution in the lowland forests of Malaya. The heart-

(Koompassia malaccensis) wood is pink in colour when freshly cut, darkening to rich red on exposure, and

the sapwood is yellowish white, about 50 mm wide. The timber is hard, heavy

and durable, with interlocked grain, and is rather difficult to work. It should be

suitable for general constructional work including bridging, and for decking. It

is suggested the wood be prebored before nailing.

Keruing (Gurjun, Yang) Keruing occurs in Malaya and elsewhere in South East Asia, and comprises

(Dipferocarpus spp.) similar species to yang from Thailand, gurjun from India and Burma, and apitong

from the Philippines. Keruing is a most abundant timber and is employed as a

general purpose hardwood. The heartwood varies in colour from light red to brown, and is clearly demarcated from the lighter coloured sapwood which is 50 mm to 75 mm wide. The grain may be slightly interlocked and the density

variable, and some parcels may be very resinous. The timber has a high stiffness

and resistance to shock loads. Although moderately durable, preservative treatment will ensure a long life. Trials by TRADA indicate that keruing is resistant to Teredo attack, and is

only slowly attacked by Limnoria, and should be preservative treated if severe biological hazard is expected. Keruing is suitable for use asfenders, rubbing pieces, sea defences, and decking

for marinas and landing stages, except where heavy duty traffic occurs.

Massaranduba This species occurs in Brazil, Guyana, Surinam, Peru, French Guiana, and the

(Manilkara huberi) West Indies. It is a heavy, dense wood, the heartwood varying from light red to

dark reddish brown. It is highly durable, and rather difficult to work. Massaran-

duba is used for mooring and sea defence piles, dolphins, piers and jetties,

groynes, bridges and marinas.

Meranti Dark red This section of the group of Shorea timbers known as meranti has special

(Shorea pauciflora et a/) properties which are suitable for heavy construction work.

The trees occur in Malaya, Sarawak and Indonesia. and the heartwood is

generally dark red to red-brown in colour, clearly demarcated from the paler

coloured sapwood, which may be from 25 mm to 63 mm wide. The grain is inter-

locked, and the wood works fairly easily and is relatively durable. It is somewhat

resistant to penetration with preservatives. Dark red, or heavy red meranti,

showed up well in TRADA trials and indicated a good resistance toTeredo,

and moderate resistance to Limnoria attack. It should be satisfactory in the

untreated state for heavy construction work.

Mora This species occurs in Guyana and Trinidad. The heartwood varies in colour

(Mora excelsa) from pale brown to deep dark red, and is sharply demarcated from the light

coloured sapwood, which varies in width from 50 mm to 150 mm. The grain is

straight to irregular, and the wood is hard and heavy, with high strength pro-

perties. The heartwood is very durable, but it is not resistant to Teredo. The wood

is rather difficult to work. Mora is extremely tough and very resistant to wear,

and is suitable for heavy duty construction where marine borer is not a hazard.

The closely related morabukea, (Mora gonggrijpii), is reported to be superior to

mora, and is used for the same purposes.

Oak This well known timber grows in Europe, Asia and North Africa. The light

(Quercus spp.) coloured sapwood is easily differentiated from the darker heartwood which is

durable but, as most oak for constructional work will contain sapwood, con-

sideration should be given to preservative treatment if the hazard is severe. Oak

is not resistant to marine borer attack. and availability in long lengths is limited.

Okan This species occurs in West Africa. It is an exceptionally hard, heavy timber

(Cyticodiscus gabunensis) which is extremely difficult to work, and has interlocked grain, The heartwood

varies from yellow to brown with a greenish tinge, but after exposure becomes

dark red brown. Okan has very high strength values, and is very durable in all

situations, having better resistance to marine borer attack in TRADA trials

than any other timber so far tested. It is eminently suitable for piling, fenders,

rubbing pieces, and as decking, where it will withstand heavy wear, and for all

sea defence purposes.

Lengths up to 7.6 metres, and sizes up to 450 mm x 450 mm are obtainable.

46


Opepe This species is widely distributed in West Africa. The orange brown heartwood

(Nauclea diderrichii) is clearly defined from the pale 50 mm wide sapwood. Opepe usually has an

interlocked grain, and is strong in bending, compression and stiffness. It is very

durable and has performed well as piling, fender piles, rubbing pieces, and for

sea defence constructional purposes. It has reasonable working properties.

Purpleheart Purpleheart occurs in Central and Tropical South America, and the West Indies.

(Pelfogyne spp.) The heartwood is dull brown when first cut, becoming intense purple for a time

on exposure, and is sharply demarcated from the greyish white sapwood. The

wood is very hard, with occasional wavy or interlocked grain, difficult to work

and tending to split when nailed. It has high strength properties, intermediate

between greenheart and oak, and is very durable. Purpleheart is eminently

suitable for sea defences, bridges and breastworks, jetties, piers, wharves,

decking and kerbs.

Pynkado This species is widely distributed in Burma, and also occurs in India. It is a dull

(Xylia dolabriformis) reddish brown wood locally speckled with dark gum. The grain varies from

straight to broadly interlocked, sometimes wavy. Pynkado is difficult to work,

but has very high strength properties, and is very durable. It is suitable for piling,

heavy constructional work, decking etc.

Tali (Missanda) Erythrophleum is widely distributed throughout tropical Africa. The heartwood

(,Zryfhroph/eum spp.) is dull red-brown, often with darker veins, and the sapwood is narrow and dull

yellow in colour. It is a hard, heavy wood, often with interlocking grain, difficult

to work, but very durable, and reported to be highly resistant to marine borers.

It stood up well in TRADA trials, and should be suitable for general con-

structional purposes in docks and harbours, and for sea defence work.

Teak Teak occurs in India, Burma, Thailand, and Indonesia, particularly in Java. It is

(Tecfona grandis) one of the world’s outstanding timbers on account of its many valuable pro-

perties, which include good strength with moderate weight, high durability, and

ease of working. It is suitable for many purposes where biological hazards are

anticipated.

47


Other suitable timbers

Afina This tree occurs throughout West Africa. The heartwood is purplish brown or

(Sfrombosia puddafa) pale brown with purplish streaks. The grain is fairly straight, and the texture is

fine and close. It is a hard heavy wood, weighing about 995 kg/m” air dry, and is

very resistant to decay. Afina is not difficult to work, and should be suitable for above water construction including flooring and decking.

African padauk This species occurs in Nigeria, the Cameroons, and the Congo. The heartwood

(Pterocarpus soyauxii) is a deep red colour when freshly sawn, turning a dull light brown on exposure.

The sapwood is commonly 100 mm to 200 mm wide, and greyish white in colour.

The grain is generally straight to slightly interlocked, and the texture is mode-

rately coarse. It is a rather hard, heavy wood, classified as very durable when

used in contact with the ground. It performed well in TRADA exposure trials,

and should be suitable for sea defence work, and for piling.

African padauk was for many years shipped to the U.K. and elsewhere in the

form of round and square logs up to 90 mm in diameter, but at the present time

supplies may be limited.

Afrormosia This tree occurs in West Africa. The timber is stable in service, and very durable.

(Afrormosia data) The heartwood darkens to a warm yellow brown colour somewhat like that of

teak, but lacking the oily nature of that wood. The grain is generally straight

except at the outside of very large logs, and the wood has a fine texture. It is

fairly easy to work, and is used mainly as an alternative to teak. It is suitable for

many purposes in marine and fresh water construction including decking.

Afzelia Various species of Afzelia are found in both East and West Africa, and are

(Afzelia spp.) known under the alternative names of doussie (Cameroons), apa (Nigeria),

chanfuta (Mozambique), etc. The heartwood is reddish brown in colour, and the

light coloured sapwood is usually from 25 mm to 50 mm wide. Afzelia weighs

about 1180 kg/m” when green, and about 800 kg/m3 at 15 per cent moisture

content. The grain is straight to moderately interlocked, and the texture is

coarse and open. It is moderately hard to work, and inclined to split when nailed

unless pre-bored. It is classified as very durable and is suitable for general

constructional purposes including decking.

Agba Agba occurs in West Africa, particularly in Southern Nigeria. There is little

(Gosswei/erodendron difference in colour between the sapwood and heartwood, the latter being only

baisamiferum) slightly darker. The wood varies from yellowish pink to reddish brown, with a

fine texture, and fairly straight grain, occasionally interlocked. It is a relatively

light weight wood, weighing about 512 kg/m” air dry, and about 800 kg/m’ green.

Agba is classified as durable when in contact with the ground, and is easy to

work, and has excellent nailing and screwing properties, and finishes well.

Agba is generally a huge tree, and very large logs are prone to the development

of brittleheart, a characteristic which renders the affected timber considerably

weaker than normal wood. Its combination of light weight, ease of working, and

high natural durability however makes agba a very valuable timber for many

forms of construction both above the water line, and under water in fresh water

locations, or where Teredo is not a problem.

Albizia The genus Albizia is widely distributed throughout Africa and elsewhere. Three

(Albizia zygia) species are commercially applicable to Africa, i.e. A.ferruginea, A.adianthifolia,

and A.zygia. There are distinct variations in weight of the species which may

reflect in quality differences, A.ferruginea varies between 576 and 800 kg/m’,

A.adanthifolia between 432 and 705 kg/m”, and A.zygia between 512 and 656

kg/m” when seasoned. Since mechanical test results indicate the lighter weight

wood of each species to be something like 50 to 60 per cent weaker in general

strength properties than the heavier wood, i.e., 640 kg/m” (at 12 per cent moisture

49


Angelin

(Andira spp.)

Ayan

(Distemonanthus

benthamianus)

Courbaril

(Hymenaea courbaril)

Determa

(Ocotea rubra)

content), it is suggested that any contemplated use of albizia should be on the

basis of a dry weight of 640 kg/m’ or more.

A.ferruginea is classified as very durable, and A.adanthifolia and A.zygia as

moderately durable. In TRADA exposure trials, the last named species was

used, and although the weight is not known, the result was encouraging, there

being a good resistance to both Teredo and Limnoria.

A.zygia is a pale brown wood with a pinkish tint. The grain is straight to slightly

interlocked, and the texture is coarse. It works fairly easily, and the heavier wood

has moderately good nailing properties. All three species have small movement

values and should be suitable for many uses in marine and fresh water construction.

Angelin is the preferred trade name for the timber from several species of Andira growing in the American tropics, of which Andira inermis is the best known and most widely distributed. It is a close relative of the rosewoods and padauks, and is found in Guyana, Surinam, Puerto Rico, the West Indies, etc., and Brazil. The wood varies somewhat among the species but is generally hard,

heavy, coarse textured, with straight to slightly irregular grain. The heartwood

is yellowish brown to dark reddish brown, somewhat resembling the darker type of Honduras mahogany.

The weight of angelin is from 720 to 960 kg/m”air dry, and about 1200 kg/m’ green.

It works fairly well, and takes nails and screws well. It is rated very durable, and

has a moderate resistance to marine borer attack. It is suitable for piling in non-

Teredo waters, and for general construction such as for bridges.

This species is found in West Africa. The heartwood is pale to bright yellow

in colour, and not clearly defined from the pale yellow sapwood. The grain is

interlocked and the texture is fine. It is moderately hard and heavy, weighing

about 720 kg/m” when seasoned, and is moderately resistant to decay. It works

reasonably well, and takes nails and screws fairly well. It has good strength

properties, especially in compression along the grain and in bending.

It should be suitable for piling in fresh water or where Teredo is not a hazard,

and for general above water construction. It performed well in TRADA exposure

trials.

The timber of Hymenaea is known under various trade names according to

origin. In Brazil it is principally known as jutaby and jatoba, while in Guyana it is

known as courbaril and locust. Other names include rode locus (Surinam), and

algarrobo (Puerto Rico).

The heartwood is salmon red to orange brown when first cut, becoming russet

to reddish brown when seasoned. The sapwood is usually wide, sharply demar-

cated from the heartwood and white, grey or pinkish in colour. The grain is

generally interlocked; the texture is medium to coarse, and the wood weighs approximately 830 kg/m’ air dry, and 1120 kg/m’ green.

Courbaril is a hard, heavy and tough wood; moderately difficult to work. It nails

badly but has good screw holding power, and tends to split easily. It is conside-

red to be only moderately resistant to decay, and to marine borers, but its high

shock resistance and reasonable strength fits it admirably for above water usage

for flooring in wharehouses and general construction, and for lock gates in

areas free from marine borers. In this latter respect, it has been used to some

extent in countries of origin.

This species is botanically related to Demerara greenheart, Ocotea rodiaei,

although the woods are quite different. The timber is commonly marketed as

determa in Guyana, as louro vermelho in Brazil, while red louro is the British Standard name.

The heartwood is light reddish brown with a golden sheen, with a well defined

cream brown sapwood about 25 mm to 50 mm wide. The grain is either straight

or roey, and the texture is coarse. It is a moderately hard and heavy wood, weighing about 950 kg/m” when green and about 625 kg/m’ when seasoned. It is

a durable wood in contact with the ground, and is easily worked. In exposure

tests in Hawaiian waters, only light Teredo attack occurred, but heavier attack

50


Essia

(Combretodendron

africanum)

Freijo

(Cordia goeldiana)

Guarea

(Guarea spp.)

ldigbo

(Terminalia ivorensis)

Kauta, Kautaballi, Marish

(Licania spp.)

occurred when samples were exposed at Harbour Island, North Carolina. It

should be suitable for sea defences, piling, and general construction, particu-

larly where risk of attack by Teredo is slight.

Essia is widely distributed in tropical Africa. The heartwood is reddish to dark

red brown, with darker veins, and the sapwood, which is often more than 75 mm

wide, is yellowish white in colour. The grain is straight to interlocked, and the

texture is moderately coarse. It is classified as durable, and weighs about

970 kg/m” green, and about 865 kg/m” when seasoned.

The timber is fairly hard to work, and tends to split in nailing unless pre-bored.

It performed well in exposure trials, and should be useful for heavy construction.

This species occurs mainly in the tropical forests of Brazil. The timber is not

unlike teak in colour, and weighs about 585 kgjm” when seasoned. The grain is

generally straight, and the texture is moderately coarse to uneven. It is classified

as durable, and it works well with all machine and hand tools. It is reputed to

have a good resistance to marine borer attack, and should be suitable for many

purposes in marine and fresh water construction including decking.

This species occurs in West Africa. The heartwood is pinkish-brown, darkening

on exposure, and the rather narrow sapwood is whitish. The grain is either

straight or wavy, and the texture is fine. The wood weighs about 576 kg/m” air

dry, and 960 kg/m” green. It is fairly easy to work, and takes nails and screws

without difficulty. It is classified as durable, and is suitable for many uses in

marine and fresh water construction including marina decking, and for under water construction where marine borer is not a hazard.

ldigbo occurs throughout West tropical Africa. The heartwood is pale yellow to

light brown in colour with little distinction between this and the sapwood. The

grain is variable; between straight to rather wavy, while the texture is somewhat

coarse and uneven. It is a soft to medium hard wood, weighing about 800 kg/m3

green, and about 560 kg/m” when seasoned. It is a durable timber which works

well, and has fairly good nailing and screwing properties.

It should be suitable for planking and decking, and for many other purposes

where stability, durability and good resistance to marine borers is essential.

Large trees of idigbo are liable to contain brittleheart, and care should be taken

in the selection of the timber if high strength is a requirement of the proposed

use.

At least nine species of the genus Licania are marketed in the Guianas, Guyana,

Brazil and Surinam, under various trade names, but the timbers are all similar,

and are all hard, heavy and strong, and rather difficult to work, generally because

of their high silica content, a factor ostensibly responsible for their high natural

resistance to marine borer attack.

Marish and kautaballi are in more plentiful supply in the Guianas and Guyana,

while kauta is reported only from Guyana. Marish is known as anaura in Brazil,

and kauston in Surinam.

Kauta is composed of three species, i.e., L.laxifolia, L.mollis, and L.persuadii,

kautaballi is usually made up from L.venosa and L.majuscula, while marish is

often composed of any one, or a combination of L.buxifolia, L.densifolia, L.mac-

rophylla, and L.micrantha.

The heartwood of all these species is generally a yellowish brown or dark brown,

sometimes with a reddish tinge; the sapwood is usually distinct and tan in

colour. The wood is straight grained with a fine, close texture. The weight of the

various species is variable, kauta is the heaviest, weighing from 1120 to 1280

kg/m” air dry, while kautaballi weighs from 1070 to 1200 kg/m”and marish weighs

from 930 to 1100 kgjm’ in the same condition.

While all species of Licania possess only a moderate resistance to decay, they

are widely known for their high resistance to marine borer. In the Wrightsville

trials, Licania macrophylla rated as the most highly resistant species of the 37

51


Keledang

(Arfocarpus spp.)

Keranji

(Dialum spp.)

Kopie

(Goupia glabra)

Makore

(Tieghemella heckelii)

timbers tested, surpassing greenheart, manbarklak (black kakaralli), basralocus,

and other woods generally considered highly resistant to marine borers.

All these timbers are reported as being available from Guyana, and kautaballi

from French Guiana.

Keledang occurs in Malaya. It is a yellowish wood when fresh, darkening to

russet or dark brown on exposure. The grain is usually irregular, and the texture

moderately coarse. It is a moderately soft to hard wood, relatively easy to work,

and not very durable when in contact with the ground. It weighs from 416 kg/m”

to 608 kgjm’ air dry. Keledang is used in Malaysia for house building and for

bridges. Despite its low resistance to decay, it showed a good resistance to

marine borer attack in TRADA trials, and it could be considered for all types of

construction where lightness of weight is an advantage.

The high resistance to marine borers suggests that these timbers would be

satisfactory for piling and other construction where the minimum of machining

is required, since the very high silica content may cause rapid blunting of cutting

edges. Tree boles are ordinarily cylindrical and 15.0 to 18.0 metres long, with

diameters of 400 mm to 600 mm.

Eight or nine species of Dialum occur in Malaysia, all producing similar timber,

and being known as keranji. The heartwood is golden brown to dark brown in

colour, well defined from the sapwood which may be as wide as 75 mm or more,

and is light brown in colour. The grain is typically interlocked and sometimes

wavy, and the wood has a texture which is moderately fine to slightly coarse,

but usually even.

The wood varies from hard to very hard and heavy, and it possesses consider-

able strength. It weighs from 800 to 960 kg/m3 air dry, and is reputed to be

moderately durable.

The uses of keranji for local consumption have been restricted because of the

hardness of the wood, but it is said to be a timber worthy of more attention

particularly as although not plentiful, it is by no means uncommon and it reaches

a reasonable size. It is used locally for boat building and general construction.

In TRADA trials, Dialum dinklagei and Dialum excelsum showed good resis-

tance both to Teredo and Limnoria, and it would appear ideal for under water

construction where marine borer was not a major problem.

Kopie is the usual trade name for timber of Goupia glabra, but it is also known

as kabukalli and stinkwood in Guyana; kopie in Surinam; sapino in Colombia,

and cupiuba or tento in Brazil, where it occurs in the Lower Amazon region. It

is found throughout Guyana, and is widely distributed in Surinam, and is a

common tree in the hinterlands of Colombia.

Kopie varies somewhat in the colour of the heartwood, in fact Guyana recog-

nises two distinct types, i.e., ‘white’, in which the heartwood is light brown, and

‘brown’, in which the heartwood is pinkish-brown. The differences would

appear somewhat academic, and based more on anatomical differences rather

than on physical properties, but the smaller pores in the ‘brown’ type produces

a finer texture, and the grain is usually more straight than that of the ‘white’ type.

Kopie is hard and moderately heavy; green wood weighs about 1170 kg/m”, and

air dry about 830 kg/m”. It is moderately difficult to work, but takes nails well. It

is generally reported to be very resistant to decay, but was rated as moderately

resistant in graveyard tests carried out in Guyana. In tests in Hawaiin waters,

and in the Wrightsville tests in the Atlantic, kopie did not show a good resis-

tance to marine borers, but it is used in Guyana for piling, decking, groynes,

revetments, and sluice gates, and should be useful for these and other purposes

in areas free from marine borers.

This species occurs in West Africa. The heartwood varies from pinkish brown

to blood red, while the lighter coloured sapwood is about 50 mm to 75 mm wide.

The grain varies from straight to roey, and the wood is classified as very durable,

Makore works fairly easily with some blunting of cutting edges particularly as

the moisture content decreases below 20 per cent. The wood tends to split when

nailed. Makore is suitable for many forms of marine and fresh water construc-

tion, and showed good resistance to marine borers in TRADA trials.

52


Mecrusse

(Androstacbys johnsonii)

Merpau

(Swintonia spp.)

Muhuhu

(Brachyleana Lutchinsii)

Muninga

(Pterocarpus angolensis)

Resak

(Cotylelobium spp. and

Vatica spp.)

Suradan

(Hyeronima spp.)

This species occurs in Mozambique and Rhodesia. The heartwood is brown or

light brown in colour, and the lighter coloured sapwood is usually narrow. The

grain is generally curly, but the texture is very fine. Although generally heavy,

about 1000 kgjm’ air dry, it is not dificult to work. The heartwood is reputed to

be very durable, and the timber has been used extensively in East Africa for

piling, harbour work and for bridges. It performed very well in TRADA exposure

trials.

This species is found in Malaya and elsewhere in South East Asia. The heart-

wood is light yellow-brown to light red-brown, not clearly differentiated from the

sapwood. It varies somewhat in weight, from 752 kg/m” to 880 kg/m” air dry,

averaging about 800 kg/m’. It is a moderately durable wood which works mod-

erately well, and has good nailing properties.

Merpau is suitable for general construction purposes above water, or in water

where marine borer hazard is not a problem.

Muhuhu is found in East Africa, generally in Kenya and Tanzania. The heart-

wood is yellowish brown with a greenish hue, and the sapwood is lighter in

colour and moderately well defined. The grain is usually straight, and the texture

fine and even. It is a hard, heavy wood weighing about 960 kg/m’ air dry, and is

somewhat difficult to work. It has a very high resistance to abrasion, and is

classified as very durable. It is also reputed to be immune to Teredo attack, but

this should be regarded with caution. Muhuhu performed well in TRADA trials,

and can be considered an extremely valuable timber for marine construction.

The tree is generally medium sized, and it is therefore difficult to obtain large

dimensions.

This species is found throughout East Africa, and also grows in South Africa,

The heartwood is brown with irregular reddish streaks, clearly defined from the

paler sapwood which is usually about 38 mm wide. The grain is rarely straight,

and is generally irregularly interlocked, and the texture is medium. The wood is

somewhat variable in weight, from 480 to 785 kg/m” averaging about 625 kg/m”

seasoned and about 1073 kg/m” green. Muninga is a very durable wood, and

showed good resistance to marine borers in TRADA trials. It is easy to work,

and nails and screws well. It is suitable for many uses in marine and fresh

water construction.

Resak is generally recognised as being the product of species of Cotylelobium

and Vatica, although the timber of the former is sometimes sold as giam. The

species are common to South East Asia, and are all similar in appearance but

somewhat variable in weight. The heartwood is yellow-brown or brown,

darkening to dark red-brown and the sapwood is light yellow with a pinkish tinge, and about 38 mm to 63 mm wide. The grain is straight or shallowly inter-

locked, and the Yetture is rather fine and even.

The wood is moderately hard to very hard depending on density, and the weight

varies from 655 kg/m” to 1055 kgjm” air dry. The durability of the heavy forms is

reputed to be very durable. It is rather difficult to work, and in the countries of

origin is generally considered a heavy constructional timber. A species of

Cotylelobium, i.e. Cflavum was exposed in TRADA trials, and showed a good resistance to both Teredo and Limnoria, and the heavier forms should be

suitable for marine construction, and the lighter forms for situations where

marine borer is not a hazard.

About 25 species of Hyeronima grow in tropical America, but only a few are of widespread importance. H.laxiflora occurs in Guyana, Colombia, and other parts

of the Amazon Basin, H.alchorneoides is known from Honduras through Central

America to Guyana and Brazil, while H.caribaea occurs in Trinidad and other

neighbouring islands. The timbers of these and other species are best known as

suradan, pilon and tapana.

The heartwood of the three species mentioned is reddish brown to chocolate

brown or dark red. The sapwood is pink and about 38 mm wide. The grain is

53


interlocked, giving the wood a striped or ribbon grain appearance, and the

texture is moderately coarse. The weight varies somewhat, but averages 785

kg/m” seasoned, and about 1185 kg/m” green. Heartwood natural durability

varies; H.laxiflora is reported as being very durable, H.alchorneoides was

classed as moderately resistant, to resistant to decay in durability tests in Costa

Rica, but in Brazil it is rated as very resistant, while H.caribaea has been reported as moderately resistant in soil tests in Trinidad. It would seem from these

reports that a rating of durable would be appropriate for the combined species.

The working properties vary from good to moderately difficult, but boring and

mortising is described as excellent. Suradan generally has good resistance to marine borer attack, and is considered suitable in the countries of origin for piling, and general construction.

Utile Utile has a wide distribution from West and Central Africa eastwards to Uganda.

(fnfandrophragma utile) The heartwood is a uniform reddish or purplish brown clearly demarcated from

the narrow lighter coloured sapwood. The grain is generally interlocked and

irregular, and the texture is rather open and coarse. It weighs about 658 kg/m’

air dry, and about 800 kg/m’ green.

Utile is classified as durable when in contact with the ground and works fairly

readily with only slight blunting of cutting edges. It has fairly good nailing

properties.

It is suitable for general construction above water, or in water free from marine

borer.

Wacapou Timber of V.americana is generally known as wacapou, and bois angelin in

(Vouacapoua americana) French Guiana, bruinhart or wakapoe in Surinam, and acapu and sometimes

wacapou in Brazil. It is a very important commercial timber tree in its Brazilian range, attaining its best development in the State of Para, and is common in French Guiana and Surinam. The heartwood is dark olive to dark chocolate in colour, clearly demarcated from the cream coloured sapwood which is normally about 32 mm wide. The grain is straight to slightly roey, and the texture is

uniformly coarse. The wood weighs about 945 kg/m” air dry, and about 1200

kg/m’ green.

Wacapou is rated as very durable when in contact with the ground, and despite

its high density is considered only moderately difficult to work, although torn

grain may result from boring. It is reputed to have a good resistance to marine

borer attack, and is used in the Amazon Valley for piling and general con-

struction.

54


TA B L E I I: Properties and working characteristics of suitable timbers

Trade Name Botanical

Name

Green

Density at

30’%, mc Bending

Ultimate green stresses

Compression Shear

parallel parallel

to grain to grain

Modulus of Impact

elasticity resistance

SOFTWOODS Kg/m:’ N/mm2 N/mm2 N/mm2 N/mm2 m

Douglas fir Pseudotsuga 673 54 25.9 7.2 10400 0.66

menziesii

Larch EurorJean Larix decidua 673 53 24.3 6.9 7900 0.86

Pine, Pitch Pinus palustris 800 Approximately 50’;; lower strength properties

American Pinus elliottii et al. than Caribbean Pitch pine

Pine, Pitch Pinus caribaea 970 66 33.0 9.2 10400 1.04

Caribbean et al.

Pine, Scats

European or

Baltic redwood

Pinus

sylvestris

625 44 21.0 5.9 7700 0.69

Hemlock Western Tsuga heterophylla 593 49 24.1 6.6 8700 0.58

(Commercial) and Abies balsamea

HARDWOODS

Balau Shorea spp. 880 to 980 No data available

Basralocus

(Angelique)

Dicorynia

guianensis

(D. paraensis)

960 No data available

Belian Eusideroxylon

zwageri

1282 143 79.9 15.4 17700 1.17

Chengal Balanocarpus

heimii


Dahoma Piptadeniastrum

africanum

849 76 36.7 11.2 9900 0.89

Danta Nesogordonia

papaverifera

1000 137 69.3 21.2 11700 1.09

Ekki Lophira alata 1314 123 68.4 16.0 13393 1.40

Elm Dutch Ulmus hollandica 641 44 18.7 7.6 5400 0.81

Elm English Ulnus procera 641 40 16.9 7.9 5200 0.66

Elm Wych Ulmus glabra 753 68 30.4 3.3 9400 0.81

Greenheart Ocotea rodiaei 1202 140 67.4 15.1 15900 1.35

56


Hardness Working characteristics Permeability

to wood

preservatives

Heartwood

natural durability

Decay Marine

borer

Wear

N

2140 Not so easy to work as European redwood.

Sometimes splits slightly when nailed. Screws

well. Sometimes resinous.

Resistant Mod.

durable

Non-

durable

Light

pedestrian

2450 Works easily. May split when nailed.

Sometimes resinous.

Resistant Mod.

durable

Non-

durable

Light

pedestrian

Not so easy to work as European redwood.

Nails and screws well. Sometimes resinous.

Resistant Mod.

durable

Non-

durable

Normal

pedestrian

3200 Heavier and more resinous than American

Pitch pine. Sometimes splits when nailed.

Mod. resistant

according to

resin content

Mod.

durable

Non-

durable

Normal

pedestrian

1960 Works easily. Takes nails well.

Sometimes resinous.

Mod. resistant Non- Non- Light

Sapwood permeable durable durable pedestrian

2050 Works fairly well. Screws and nails easily,

with slight tendency to split if nailing occurs

too near the end of the piece. Some parcels

contain a proportion of the weaker balsam fir.

Resistant Non-

durable

Non-

durable

Light

pedestrian

-.

Works fairly well. Resistant Durable Mod.

durable

Normal

pedestrian

Rather difficult to work, depending upon

amount of silica present. Tends to split

when nailed.

Probably highly

resistant

Very

durable

Very Probably heavy

durable industrial

12630 Difficult to work. Probably highly

resistant

Very

durable

Very

durable

Heavy

industrial

5670

Works fairly easily. Screws and nails well.

Moderately difficult to work.

Nails well. Interlocked grain.

Probably

resistant

Resistant

Mod.

durable

Durable

Mod.

durable

Non-

durable

Light

industrial

Light

pedestrian

9520 Works fairly well. Tends to split when nailed.

Slightly interlocked grain.

Resistant Durable Mod. Light

durable industrial

12850 Difficult to work. Cannot be nailed without

pre-boring. Interlocked grain.

Very hard and heavy timber.

Extremely

resistant

Very

durable

Very

durable

Probably heavy

industrial

3380

3960

3960

Dutch and English elm works readily and takes

nails without splitting.

Wych elm has good working properties

and straighter grain.

Moderately

resistant

Moderately

resistant

Resistant

Non- Non- Probably heavy

durable durable pedestrian





8360 Difficult to work. Tendency to split.

Pre-boring is necessary for screws.

Straight grained.

Extremely Very Very Heavy

resistant durable durable industrial

57


TABLE 11: Confinued

Trade Name Botanical

Name

Green

Density at

30 7; mc

Ultimate green stresses Modulus of Impact

elasticity resistance

Bending Compression Shear

parallel parallel

to grain to grain

Kg/m:* N/mm2 N/mm2 N/mm’ N/mm’ m

Ipe (Guayacan) Tabebuia

guayacan

993 437 77.6 19.4 13900 -

Based on dry sample at 12% mc

lroko Chlorophora

excelsa

817 74 35.3 10.3 8300 0.71

Jarrah Eucalyptus

marginata

1009 72 37.2 10.3 9600 -

Kapur (Sabah) Dryobalanops 865 81 41.2 8.5 10900 0.71

beccarii

Karri Eucalyptus

diversicolor

1041 77 37.6 10.4 13400 -

Kempas Koompassia

malaccensis

1100 76 42.0 10.3 13000 -

Keruing (Malaya) Dipterocarpus spp. 929 83 43.1 - 16000 0.69

Manbarklak (Black Eschweilera spp.

Kakaralli)


Massaranduba Manilkara hoberi 1120 to 1400 No data available

Meranti Dark red Shorea pauciflora 609 63 32.0 - 9700 0.66

Mora Mora excelsa 1137 94 49.4 12.5 14800 0.86

Oak (U.K.) Quercus spp. 833 59 27.6 9.1 8300 0.86

Okan Cylicodiscus gabunensis

1185 101 56.7 16.6 12800 -

Owe Nauclea

diderrichii

945 94 51.6 13.1 11900 0.81

Purpleheart Peltogyne spp. 1105 105 56.5 14.9 14000 1.04

Pynkado Xylia

dolabriformis


Tali (Missanda) Erythrophleum spp. 1362 124 71.2 16.7 13300 1.07

Teak (Burma) Tectona grandis 817 84 42.8 10.1 8800 0.86

Table II Notes (A/l data is taken from P.R.L. Bulletin 50 and similar publications)

Trade and botanical names: As per BS 589 and 881 : 1955: Reprinted 1972: Nomenclature of Commercial

Timber including Sources of Supply.

Green density: Average density at approximately 30% moisture content.

Modulus of rupture: Maximum bending strength. Equivalent fibre stress at maximum load kg/m2

Compression: Maximum compressive strength parallel to grain N/mm*

Shear: Maximum shear strength parallel to grain N/mm2

Modulus of elasticity: Modulus of elasticity N/mm2

Impact resistance: Resistance to suddenly applied loads. Maximum drop of 23 kg hammer

58


Hardness Working characteristics Permeability

to wood

preservatives

Heartwood

natural durability

Decay Marine

borer

Wear

N

12720 Difficult to work. Probably Very Non- Light resistant durable durable industrial

4800 Works fairly well. Takes nails and screws well. Extremely Very Mod. Light

Tendency for grain to be interlocking. resistant durable durable pedestrian

5690 Hard to work. Hard to nail, but holds screws

firmly. May have interlocked or wild grain.

Gum veins and pockets do occur.

Extremely Very Very Normal

resistant durable durable pedestrian

3870 Works moderately well. Screws and nails well. Extremely Very Probably Normal

Straight grained. resistant durable very durable pedestrian

6050 Hard to work. Hard to nail, but holds screws firmly. May have interlocked or wild grain,

but not so common as with jarrah.

Extremely Durable Non- Normal

resistant durable pedestrian

6040 Fairly difficult to work. Probably Durable Non- Normal

Takes nails fairly well. resistant durable pedestrian

4090 Variable. Resin may be troublesome. Screws and nails well.

May contain slightly interlocked grain.

Probably Mod. Mod. Heavy resistant durable durable pedestrian

Difficult to work. Extremely Very Very Probably heavy resistant durable durable industrial

Fairiy difficult to work. Probably Very Mod. Heavy

Takes screws and nails well. resistant durable durable pedestrian

2490 Works fairly well. Takes screws and nails well. Resistant Durable Probably Normal

very pedestrian

durabte

7520 Fairly difficult to work. Holds nails firmly. Extremely Durable Non- Probably heavy

May contain irregular grain. resistant durable industrial

4670 Medium working properties. Screws and nails Extremely Durable Non- Heavy fairly well, but pre-boring may be necessary resistant durable pedestrian

11250 Very difficult to work. Needs pre-boring for Extremely Very Very Heavy

nails and screws. Has interlocked grain. resistant durable durable industrial

6760 Moderately easy to work. Interlocked and wavy

grain does occur. May split when nailed. Screws well.

Moderately Very Very Normal


9160 Difficult to work. Tends to split when nailed.

Generally straight grained,

occasionally interlocked or wavy.

Extremely Very Non- Heavy


10320

4140

Difficult to work.

Difficult to work. May contain interlocked

or wavy grain.

Variable, but generally moderately easy to work. Takes nails and screws fairly well.

Extremely

resistant

Extremely resistant

Extremely resistant

Very durable

Durable

Very durable

Very Heavy durable industrial

Very Normal

durable pedestrian

Mod. Light durable pedestrian

Hardness:

Wear:

Hardness on side grain Timbers are classified into five groups: Pedestrian traffic

Light Residential and domestic interior Normal Public buildings interior. Less than 2000 persons per day Heavy Public buildings-more than 2000 persons per day in traffic lanes

Industrial traffic Light Light trucking

Heavy Heavy trucking and impact loading

59


TA B LE I I I: Main uses, sizes and availability of suitable timbers

Species trade name

Main uses Sizes normally available. As imported or produced (mm)

Lengths normally available

(m)

Other sizes obtainable SUPPlY

SOFTWOODS

Douglas fir Piling, fender piles, 75 x 100 to 75 x 300 2.5 to 1.3 Longer lengths and larger sizes Fair

lock gates, sea defence 100 x 100to100 x 300 difficult and subject to

groynes, and decking, 150 x 300, 300 7. 300, 4.8 to 12.0 special importation

(edge grain) 350 x 350

Larch

European

Piling and planking, Ex logs up to about Ex logs up to Good in

sea defence groynes etc. 750 mm diameter about 9.0 Scotland,

Some square edged limited in

England and

Wales

Pitch pine

mainly

Caribbean

Piling, fender piles and up to 150 x 150 to

rubbers, Lock gates, 406 x 406

sea defence groynes, Up to 508 x 508 to

and decking special order

3.0 to 7.6 Longer lengths obtainable,

but with difficulty over 10.6

metres

Good

European Rubbing pieces, planking, 75 x 100 to 75 x 275 In the range, A comprehensive range of sizes Good

redwood waling. General purpose 100 x 150to 100 x 275 1.8 to 6.3 in readily available. Longer lengths

(Baltic and timber 300 mm occasionally available

Russian) increments

(Scats pine)

Hemlock

Western

Sea defence groynes,

decking and temporary

work

up to 350 x 350 up to 7.3

7.6 to 12.0

in limited

quantity

Over 12.0 metres not usually

available. Larger sizes up to

600 mm x 600 mm sometimes

available

Fair

HARDWOODS

Balau Sea defence and mooring 50 x 150 to 75 x 300 3.0 to 7.6 Lengths over 7.6 metres limited Fair

piles, groynes, dolphins, 100 x 225 to 300 x 300 3.0 to 9.0

locks, fenders and rubbers, 150 x 150 to 250 x 250 3.6 to 7.6

marinas etc.

Basralocus Piles; main, fender, Hewn; 225 x 225 3.6 to 9.0 Lengths of 21.3 metres or longer, Fair

mooring, and sea defence. +or-25 generally on forward shipment

Jetties, piers, groynes etc. Hewn: 300 x 300 to 9.0 to 21.3 by negotiation with supplier

450 x 450

Belian Piling and planking, sea No information available Limited

defence groynes, decking

Chengal Sea defence and mooring 100 x 225 to 300 X 300 3.0 to 9.0 By negotiation with supplier Limited

piles, ties, groynes, piers 150 x 150 to 250 x 250 3.6 to 7.6

and jetties, bridges, etc.

Dahoma Fenders, piling and

planking, sea defences

up to 450 x 450 up to 7.6 By negotiation with supplier,

ex round logs converted in

UK, usually

Limited in UK

Abundant in

West Africa

Danta Piling, planking and

decking, sea defences

up to 450 x 450 Up to 7.6 By negotiation with supplier, Good

ex round logs usually 3.6 to 7.3

metres long, averaging 4.5 metres

Ekki Piles, decking, waling and 100 x 225 to 350 x 350 3.0 to 9.0 By negotiation with supplier, Fair in UK.

planking, rubbers and 150 x 150to250 x 250 3.6 to 7.6 ex round logs Abundant in

fenders West Africa

SO


Species trade name

Main uses Sizes normally Lengths available. normally As imported available or produced (mm) (m)


HARD WOODS

Elm Fenders and rubbers,

decking, sea defences,

waling, and lock gates

Common elm; ex logs Up to 9.0 Lengths in excess of 9.0 metres Good

up to 915 mm diameter, usually limited

Wych elm; ex logs

up to 750 mm diameter

Greenheart Piles and fendering, Round ; By negotiation with supplier Good

lock gates, decking and 3501425 dia. Butts 9.0 to 24.3

planking, sea defences, 25Oj300 dia. Butts 3.6 to 9.0

groynes, piers and jetties, Hewn; or more

bridges, marinas, etc. 225 x 225 + or - 25 3.6 to 7.3

300 x 300 to 450 x 450 9.0 to 15.3

Sawn ; 50 x 225 to 75 x 225 3.0 to 7.6

150 x 300 to 400 x 400 3.0 to 15.3

200 x 200 to 250 x 250 3.6 to 9.0

300 x 300 to 400 x 400 9.0 to 15.3

Ipe Jetties, piers, dolphins,

sea defences, walings,

bridges

100 x 225 to 350 x 350 3.0 to 12.0 By negotiation with supplier Limited

lroko Piles, sea defences,

docks, decking and

planking etc.

25 to 100 thick

150 to 600 and wider

1.8 to 6.1 By negotiation with supplier, Good

generally ex logs:-

Round; 600 mm to about 1600 mm

dia. 4.2 metres and up long

Square; 450 x 450 and up; 3.6

metres and up

Jarrah Piles, fenders and rubbers, 50 x 150 to 150 x 300 3.0 to 7.6 25 mm to 150 mm thick. Good

decking, lock gates, and 100 x 225 to 300 x 300 3.0 to 7.6 75 mm to 300 mm wide

sea defences, etc. 150 x 150 to 225 x 225 3.6 to 7.6

Kapur Sea defence and mooring 50 x 150 to 150 x 300 3.0 to 7.6 25 mm to 38 mm for decking Fair

piles, groynes, piers and 100 x 225 to 300 x 300 3.0 to 9.0

jetties, decking, dolphins, 150 x 150 to 250 x 250 3.6 to 7.6

bridges, fenders and rubbers

Karri Rubbing pieces, decking, 50 x 150to150 x 300 3,o to 9.0 25 mm to 38 mm for decking Fair

sea defences 100 x 225 to 350 x 350 3.0 to 7.6

Kempas Fenders and rubbers,

sea defences

50 and up thick

150 and up wide

3.0 and up By negotiation with supplier; Limited in UK

large sizes tend to be restricted

by natural occurrence of hard,

stone-like veins in some logs

Keruing Sea defences, lock

gates, and decking

25 x 150 to 150 x 300 3.0 to 7.6 By negotiation with supplier Good

Manbarklak Sea defence and mooring Hewn; 3.6 to 7.6 By negotiation with supplier Fair

piles, ties, groynes, piers 225 x 225 + or - 25

and jetties, bridges, etc.

Massaranduba Sea defence and mooring Hewn; By negotiation with supplier Limited on

piles and ties, groynes, 225 x 225 + or - 25 3.6 to 7.3 large sizes,

piers, jetties, dolphins, Sawn ; otherwise Fair

bridges 100 x 225 to 350 x 350 3.0 to 12.1

Meranti

Dark red

Decking, fendering,

planking, etc.

up to 100 x 300 up to 7.3 Larger sizes and longer

lengths difficult

Good

61


T A B L E I I I : Continued

Species trade name

Main uses Sizes normally Lengths available. normally As imported available or produced (mm) (m)


HARD WOODS

Mora Piling, sea defences, fenders and rubbers

No information available Not available in UK unless

on forward shipment

Oak (UK) Sea defences, rubbing pieces, lock gates, planking, etc.

50 x 225 to 75 x 300 3.0 to 7.6 Large sizes and long lengths difficult

Becoming limited

Okan Piling and rubbers, sea defences, jetties, piers, dolphins and bridges

100 x 225 to 250 x 350 3.0 to 9.0 Some stocks in 50 x 150to 150 x 300 3.0 to 9.0 UK Good in

West Africa

Otwe Sea defence and mooring 150 x 150 to 250 x 250 3.6 to 7.6 25 mm to 38 mm for decking Good piles and ties, jetties, 100 x 225 to 350 x 350 3.0 to 9.0

piers, dolphins, decking, 50 x 150 to 150 x 300 3.0 to 9.0

lock gates etc.

Purpleheart Jetties and piers, 100 x 225 to 300 x 300 3.0 to 9.0 25 mm to 38 mm for decking Fair dolphins, decking, sea 50 x 150to 150 x 306 3.9 to 7.6 defences, bridges

Pynkado Piles, bridges, decking,

sea defences

No information available By negotiation with supplier Not available in UK unless

on forward

shipment

Tali Decking and planking,

bridges, fenders and

rubbers

25 and up thick

75 and up wide

1.8 and up By negotiation with supplier.

Present availability in UK

confined to flooring strips

Good in East

and West Africa

Teak Decking, planking, sea Extensive range; 1.8 and up Good defences, piers, jetties, etc. 25 to 100 thick av. 24 to 2.7

150 to 350 wide

Table III Notes Sizes normally available

The sizes given in the Table are those in common use in marine and fresh water construction. In some cases they are as produced in this country from logs or large baulks, in others they are as imported. In this latter respect, it should be noted that some countries still produce their timber to imperial dimensions and

furthermore, control their sizes within the limits of tolerances laid down in the grading rules of the country in question. It is therefore important for the designer or specifier, to consult his timber supplier

as to the actual sizes available as early as possible in the design stage.

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Acknowledgements

The Timber Research and Development Association wishes to acknowledge

the assistance given in the revision of this publication by:-

Mr C. J. Cowen Millars Constructional Woods Ltd.

Mr V. S. Evans Mallinson & Eckersley Ltd.

Mr J. Hester and Mr A. Duvivier G. R. Wiltshire & Co. Ltd.

Mr D. Holland Burt Boulton (Timber) Ltd.

Mr T. S. Mallinson William Mallinson & Denny Mott Ltd.

Mr G. J. Pleydell United Africa Co. (Timber) Ltd.

Mr Stoneman Savack Service Ltd.

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Bibliography

Aaron J. R. 1954 The use of Forest Produce in Sea and River Defence in England

and Wales Forestry Commission Record 29

British Standards Institution Nomenclature of Commercial Timbers including

BS 881 & 589: 1955 Sources of Supply

BS 913: 1954 Pressure Creosoting of Timber

BS 3452: 1962 Copper/Chrome Water Borne Wood Preservatives and

Their Application

BS 4072: 1966 Specification for Wood Preservation by means of Copper/Chrome/

Arsenic Compositions

CP 112: 1971 The Structural Use of Timber (Metric Units)

Building Research Establishment

Princes Risborough

Laboratory 1972

Princes Risborough

Laboratory 1957

Princes Risborough

Laboratory 1969

Canadian Institute of Timber

Construction 1959

Clapp William F. 1949 to 1955

Cotton K. E. 1956

Oliver A. C. and

Woods R. P. 1962

Oliver A. C. and

Richardson H. 1959

Oliver A. C. and

Woods R. P. 1960

Pedlingham R. S. T. and

Hall B. 1962

Pannell J. P. M. 1960

Saunders R. G. and

Hall G. S. 1967

Timber Research and

Development Association and

British Wood Preserving

Association 1956

United States Steel International 1969

Handbook of Hardwoods

Handbook of Softwoods

The Strength Properties of Timbers

2nd Edition: Metric Units,‘Bulletin 50

Timber Constructional Manual for Architects and Engineers

Tropical Wood Marine Borer Tests, Harbour Island, North Carolina

William F. Clapp Laboratory Progress Reporfs I-II

The Use of Timber in the Construction of Sea Defence and

River Works

Brifish Wood Preserving Associafion Convention Record 5-43

The Natural Resistance of Certain Timber Species to Marine Borers:

Third Progress Report

Timber Research and Development Associafion. Test Record BITRI5

Sea Defence Groynes

Timber Research and Developmenf Associafion lnformafion Bullefin BIIBII

The Resistance of Certain Timbers to Shingle Abrasion

Timber Research and Developmenf Associafion Tesf Record B/TR/4

The Structural Use of Greenheart

The Dock and Harbour Authority 43 (501)

Timber in Dock and Harbour Engineering

The Dock and Harbour Aufhorify

Marine Borer Resistance of Timbers

Timber Research and Developmenf Associafion Research Report B/RR/S

Timber Preservation

Marina Design and Construction

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