L A K E M A C Q U A R I E Y A C H T C L U B

C R U I S I N G D I V I S I O N

June 2020 No. 366

Silk waiting patiently to sail again Photo by Lanyuan Wang

Page 2 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

Please address all letters for the Cruising Division to:

LMYC CRUISING DIVISION

Ada Street

Belmont NSW 2280

Alternatively, letters for the Cruising Division may be left

in the ‘pigeon hole’ at the LMYC office.

Cruising Division Editor:

Any articles for the Cruiseletter can be sent to

Cruiseletter Editor David Baker, preferably in MS

Word format.

dragonflydbl@gmail.com (0427 317109)

by 25th of each month.

Skippers Report 3

Covid 19 Boating Update 4

For the Love of a Boat 5

Cruising Division History 8

The Story of Kathleen 10

Technical Tips - Anchoring 13

Book Review - Longitude 16

CD Calendar of Events 2020-21 17

Cruising Division Executive

Skipper: Committee

Tony Austin 0416266947 Trevor Smith 0413719329 Michael Norwood 0401622954

Secretary: Ken Archer 4946 7751 Maureen Seysener 4975 2561

Cath Austin 4946 9928 Rob & Karen Black 0417215300

Treasurer:

Ross Shirtley 4945 0641

by Tony Austin

Greetings fellow CD Members,

It has been over two months since the LMYC closed its doors. The world has certainly changed over those two months and we have not been immune to those changes. Hopefully you and your families have been spared the trauma of contracting COVID-19. Luckily our case numbers in the Lake Macquarie/Newcastle area have been very low and I am sure that you will join me in saluting the efforts of all those in the community who have worked so professionally to keep us safe. I still marvel at how we are comparing to so many other countries. Fingers crossed it remains like this into the future.

As you are all aware, NSW is gradually reducing the restrictions that’s have been in place for the past few months. We hope to see LMYC reopen very soon and the CD will be able to conduct on water activities (albeit within the ongoing social distancing rules) which will be great. The issue of face to face CD meetings remain a challenge at this stage but we are working with the CEO of LMYC to explore some options that might make these possible.

It has been great to see some of our really dedicated members braving the cold, windy and rainy conditions to get out on the water. I have to confess that I did not get very many of the maintenance tasks done that I had vowed to do but what the heck - there is always tomorrow! As we move into winter we can look forward to some great conditions on the lake with still days and very few other boats to break the tranquility of our favourite anchorages. Make the effort and get out there!

On behalf of the committee I want to wish you and your families a safe time ashore as well as afloat.

Safe sailing,

Tony Austin Skipper

Once again we have some interesting articles from members. Thanks for your contributions, they all contribute to our understanding and enjoyment of yachting. I look forward to hearing from any members who have read interesting books or magazine articles lately. Just send me a few words that tell us what you thought of the material and where we can find it so we can enjoy reading them as well.

As we take advantage of newly relaxed restrictions, I feel obliged to mention that Fred and Maureen’s lovely story about Escaping the Lockdown Blues in the May edition was written before the restrictions on overnight boating were announced. Hopefully, we can all now go out and enjoy overnight cruising while maintaining social distance at shouting range.

Best wishes and fair winds.

David the Editor.

LAKE MACQUARIE YACHT CLUB CRUISING DIVISION PAGE 3

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COVID-19 boating update I’m sure that by now everyone is rejoicing that we can use our boats so long as we continue to act responsibly. Here is an update affecting our ability to cruise the lake - as of 15th May when I downloaded it from https://maritimemanagement.transport.nsw.gov.au/about/news/covid-19-response.html

Transport for NSW and NSW Maritime appreciates that many boaters and community members have ques-tions about the public health directions and how they relate to water-based activities.

From 14 May 2020, NSW Government Public Health Orders have been updated to ease some of the previous restrictions across NSW. View the latest information about Public Health Or-ders here.

Recreational Vessels

All recreational boating is permitted, however, the skipper must still ensure there is four square metres of space for each person on board.

People should still only boat locally and always remember to practice good personal hygiene.

Commercial Vessels

Commercial and charter vessels may operate, but must ensure they are operating within the re-strictions associated with their category of business and the required distancing requirements.

Onshore activities

When onshore, do not gather as more than 10 people (unless with members of the same house-hold). This applies in any public place, such as a wharf or publicly accessible vessel. Skippers must also remember their other safety responsibilities regarding safety equipment, alcohol con-sumption, keeping a proper lookout and proceeding at a safe speed.

Further information about what you can and can’t do is available here.

Information about boat ramps

Contact your local council for more information about specific boat ramps. There are no current plans to close the ramps managed by Transport for NSW.

Also https://www.sailing.org.au/news/what-do-easing-covid-19-restrictions-mean-in-my-state/ which

you hopefully received from the club if you are on Facebook.

• Yachts – Yes, provided you maintain a maximum of 1 person per 4m2 and social distancing of 1.5m and hygiene requirements are maintained. Maintain only outdoor gatherings of up to 10 people.

• Dinghies (single handed) – Yes, provided you maintain a maximum of 1 person per 4m2 and social dis-tancing of 1.5m and hygiene requirements are maintained.

• Dinghies (double Handed) – No. These boats are unable to comply with the 1 person per 4m2 and so-cial distancing of 1.5m requirements.

• Powerboats – Yes, provided you maintain a maximum of 1 person per 4m2 and social distancing of 1.5m and

hygiene requirements are maintained. Maintain only outdoor gatherings of up to 10 people.

PAGE 5 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

Ian Donaldson

In 1969 Coleen and I moved to New Guinea two weeks after our wedding day for work. With a two year contract in hand we had to make a decision on how to fill in our spare time. Our decision was not a difficult one with temperatures always in the 30’s, trade winds building to 25kts every afternoon (April to December) and nice sandy beaches on nearby islands - so lets build a boat. That decision started a saga that has gone on for over 40 years.

Stepping farther back in time, it really started in the late 50‘s at age 15 using sheets of flattened corrugated iron bent up into a canoe shape, sealed with tar from roadways and paddled on the Nambucca River - over the years graduating to VJ’s and Quickcats.

So going forward to New Guinea I made the decision that, with a bride to impress, I would show some responsibility and build a Lazy E - a Jack Holt English design 16ft open dinghy. Marine ply was very cheap at $8 for a 1200x2400 sheet. Decision made, plans acquired from a fellow boaty,

and materials ordered, stakes were driven into the ground to form level trestles next to our donga. Hardware was readily avail-able from Steamships Trading Company (think Bunnings) and sails mast and boom direct from UK (delivery from UK 4 weeks, Aust 6-8 weeks). As I did not have facilities for steaming to bend timber I placed wet bags over the ply for the day and after work tightened the clamps, this worked well over the few

weeks it took to achieve the right curves. The original design was for slatted seats and air bags for buoyancy, this I altered to built-in en-closed seats for extra buoyancy. Customs clearance papers in hand I was told to “help myself” to collect the mast sails etc. from the wharf. It

was interesting to note in the wharf shed Roundup stacked on top of bags of sug-ar and flour, and a big box of thongs opened, with old thongs replaced for new - the wharfies did look smart. With rigging checked, trial hoist in back yard, launch party over, we spent the next few years enjoying sailing the harbour reef and local is-lands with boat number 1.”Wizard of ID”.

Our work contract was extended and a couple of our friends decided to build Tornados, so I got myself involved in helping build tortured ply construction Tornados. This left us well behind in boat speed so looking around I stumbled across a half finished Yvonne catamaran 20ftx8ft - all solid ply construction with a 6ft single centre board in between the hulls. There was room to fit an esky in the hulls. It was a Lindsay Cunningham design, the first catamaran designed to fly a spinnaker. We raced this some Saturdays with the Royal Papua Yacht Club and were clear winners. We have very fond memories of lazing on the deck of Libra cruising along the inside of the outer reef watching turtles and sea snakes slip between the hulls.

With a third contract extension and with first baby on the way we decided that a keel boat would be safer, so ended boat number two. Boat number 3 was my own design. I made a 1/10 scale half model from balsa wood, with a hard chine similar to a hood 20. This was to have a cabin to keep tropical sun off bub and also be outboard driven.

PAGE 6 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

The construction method for boat ‘numba 3’ was plywood stitch and glue. For the technically minded, I laid tracing paper over each of the 3 panels on the model and traced the chine outline, drew a centre line on the paper template for each panel and marked 10 equal offsets along the centre line. I then scarfed 3 sheets of ply together (nailed to the verandah floor). The centre line and full size offset dimensions were transferred to the ply-wood for each panel. A batten was then used to join all of the offset points into a sweet curve to be jigsaw cut.

Each panel was matched up and pulled together with copper wire twitched on the outside, and thus the shape was loosely formed. Bulkheads were then pushed into place to hold a firm shape. Fibre glass tape was applied on the inside which locked the joint solid. The outside soft copper wire was planed off and fibre glass tape applied to the outside. The Keel was 15 pieces of 4’x2’ doweled together with lead from tele-com cable offcuts melted in a half 6” pipe on the BBQ. The

next challenge was to select a long piece of knot free pine timber to be routed out to form the hollow center and bolt rope groove to make the mast and boom. The two halves were then glued together and Geko was launched, com-plete with sails and motor for $600. The launch was inter-esting, as we towed the boat on a make shift trailer behind a Morris 1100. During the launch proceedings a very in-quisitive sea snake kept chasing us as we entered the wa-ter. Geko saw out our stay in Papua New Guinea and we sold it for $3000 when we “went finish” - so ended boat project three.

Back in Australia we had to finish off building our house - Coleen issued orders “no more boat building”. To fill in our weekends we bought a HOBIE 16, boat number 4, “Mellow Yellow”. It was lots of fun, and so I became involved in forming the Newcastle Catamaran Club as first

president. We ran a regatta from Rathmines of some 250 boats at its peak. However, the blue water was calling for us to start another project, number 5, hence “Gambert”, a Swanson 38, was conceived .This involved taking 5 weeks off work, traveling to Wyong, hiring the moulds and laying up the hull deck and lead keel. This was then transported up to Bolton Point by truck and set up in our yard so I could step off the BBQ deck straight onto the deck of the boat. This then became a 7 year project. Boat building was a balance between family time and work. The Perkins motor I

imported from UK, the timber was western red cedar plank lining, teak cupboards and Australian hardwood bench tops. I made all the rigging fittings, including turnbuckles spreaders etc., except for swaging. Before the mast was stepped we motored up to the Myall Lakes and Bulahdelah, spending about 3 months in the area - a very enjoyable time. One incident occurred when on a Saturday morning I received a call from Swansea base asking when I was going up to the boat (I usually left it on anchor north side of Leggs Camp). The mes-sage was passed from the sanny barge Myall Lakes to Tamboy, to Port Stephens, then to Swansea to say they would wait to see if I needed help to get Gambert extracted from the reeds. It had been blown into the reeds by a stiff southerly.

PAGE 7 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

After sailing Gambert for 5 years our thoughts turned to the Whitsundays, which meant a Catamaran, so project number 6 was born, “Boomaroo” a Tony Grainger 38. At that time there were not a lot of produc-tion cats on the market, ones that could sail anyway, so construction started in Berrys Bay in Sydney where a cabinet maker was full time employed and I spent 3 days a week with him, sleeping in my car in the shed. Construction was west system strip plank 15mm thick with a single layer of 600gm matt fibre glass inside and out. We finished the catamaran in 3 months to lock up stage, which was enough to motor it up to the Lake. It took the next 5 years to complete, pulling the bows up on shore and running a power cord across the park to an oblig-ing neighbor. Some aspects of the original design were changed

and subsequently incorporated in future Grainger designs. The interior material finish was ‘‘nomex” scrap flooring from Qantas aircraft. When it was time to step the mast, (constructed in the back yard), it was wheeled from home to the water some 200m, one end in back of the station wagon other end in a wheelbarrow. Quite unconventional transport.

Boomaroo gave us 17 years of fabulous cruising with no bad habits, lots of party time and the opportunity to meet just the nicest, most helpful people. You may guess by now that years must be catching up with us, so with Boomaroo sold to West-ern Australia - project 6 had gone.

Project 7 is a NO BUILD. You may know her as Chandon, a Jeanneau 40 deck saloon. We hired one in Scotland and cruised the Western Hebridean Islands and felt very comforta-ble with its qualities for cruising at our age, shallow keel, furling sails, big motor with good range, and storage. In the 2 years we have skippered her she has taken us to Magnetic Island

and up and down locally and so far has behaved well. We plan to keep cruising, exploring new interesting places and meeting like minded cruisey people.

PAGE 8 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

It is interesting to read the history of the Cruising Division compiled by Life Member Mike

Collins. Reading the record of events and the challenges that earlier members overcame

provides perspective on where we are at this time as a group of cruising enthusiasts.

LAKE MACQUARIE YACHT CLUB CRUISING DIVISION PAGE 3

An interesting note in the March 1990 minutes concerning membership of LMYC and

member insurance.

Katheen, Kathleen Gillett and the Book.

Ray Kiely

I first met Kathleen whilst waiting for a tram at the stop in front of Percy Pigeon’s News Agency in Hunter Street. In the win-dow was a magazine which really grabbed my attention. It was the inaugural copy of Seacraft, the July/August 1946 edition. At 2/- it would leave me with just enough for the fare home. I would buy every copy until I went OS in the early fifties, and still have most of them. They are not in the best of condition now as they lived in a carport for a few years. The lead story covered the first Sydney-Hobart yacht race and the image on the left was scanned and cropped from the cover of that first edition. It is a painting by Theo Kielly of Kathleen, tops’l set, competing in that race.

A Catalina came from Rathmines and covered the race, and many years later I did a lot of busi-ness with one of the pilots. The next I heard of Kathleen was when Seacraft serialized her cir-cumnavigation of the world. This was what she was built for, long distance cruising.

In the November 1947 issue of Seacraft, Kathleen Earl, shore bound wife of Jack, wrote an article on “Kathleen” and her crew in which the yacht’s name was clearly Kathleen. Designed by Colin Archer, it was typical of his designs, double ended and husky. She was a gaff rigged ketch. Quoting from the article “…although urged by seafaring friends to change the original sail plan for a Marconi, Jack decided to retain the picturesque though old fashioned gaff rig. He now regrets these youthful convictions” (A true romantic!).

Construction of Kathleen started in 1933 and work continued as funds became available, and she was launched in 1939. Once in the water, Jack, Kathleen, and their two children took up residency. The masts were stepped in 1941 and the boat went into service as part of the Naval Auxiliary Patrol (as did many of LYMC and RMYC boats also). Kathleen was planked below the waterline with 2¼” spotted gum and above with Huon Pine. The mast is 12” in diameter at the goose-neck and the other spars are hollow

The voyage started on Saturday 7th June 1947 and Kathleen sailed back into Sydney Harbour

exactly 18 months later, the 7th December 1948. She left Sydney with a crew of 5 but departed

Australia from Thursday Island with 4 as one member was unable to overcome sea sickness on

the first leg to Gladstone, a passage of 5½ days. He would be replaced at Durban. The route

from here took them across the Southern Atlantic, through the Panama Canal and across the Pa-

cific and home a voyage of some 26,000 nautical miles. That was the last I heard of her until

about 1987 when she turned up in the news again as Kathleen Gillett and the missing years were

accounted for.

The Earls sold her in 1950 and no doubt she would have been Kathleen Gillett at that time as

none of the many future owners would feel the need to so honour Mrs Earl. In the ensuing years

the yacht would spend most of her life in the tropics and much of that time she was gainfully

employed in many roles. She would be an island trader, charter boat, cargo carrier, tourist boat,

crocodile hunter and even a pleasure yacht.

One of the many owners in these 30 plus years

would give her aluminium spars, a mast head Ber-

mudan rig, and her 12’ bowsprit was much short-

ened which would make coming alongside less

risky. 1975 found her in Guam where she fell

victim to a cyclone that drove her ashore and

stranded her on a coral reef within the harbour.

Efforts to salvage and repair her over the next few years came to nothing, primarily because of lack of funds and an inability to raise them. For many years she remained a derelict. In 1987 she was acquired by Norway, shipped to Australia for restoration by Lars Halvorsen Sons P/L and then presented to Australia in 1988 as a gift celebrating our first 200 years, and is now on display at the Maritime Museum in Darling Harbour, Sydney.

The Designer

The first of the Archer family migrated to Queensland in 1834, and others including Colin followed later. They became pastoralists and worked several holdings. Colin would return to Norway in 1861 where he studied ship building and design. He would go on to build more than 200 boats and designed many more. Over time, the term ‘Colin Archer type’ became generic no matter who designed them. In the 1890’s he was commissioned to design a vessel for Nansen’s proposed attempt to reach the Arctic Pole. This vessel was the Fram and became a famous hallmark for seaworthiness. Getting as far as he could, Nansen drove Fram into an ice pack and, being frozen in, Nansen hoped they would drift nearer to their goal. This did not work and eventually Fram and her ice squeezing berth were allowed to drift unmanned, eventually bringing up in the North At-lantic where after some 3 years (1893-1896) locked in the ice she was found to be none the worse for her ordeal. It didn’t hurt Colin either.

Kathleen was one of Archer’s designs and her plans were jealously guarded by her Sydney builder. Those who may have read Erling Tambs’ “Cruise of the Teddy” would know that Teddy, designed and built by Archer, was a superannuated Norwegian Pilots’ Boat already 38 years old when he and his wife started their cruise in 1928. At 40’ she was slightly smaller than Kathleen and rigged as a gaff cutter. Colin Archer died in 1921 in his 89

th. year.

Now the book of the voyage. This became the Holy Grail for me, but as it was pre the Internet, all I could do was pop into every second hand bookshop I en-countered, from the Gold Coast to Hobart to Fremantle, without suc-cess. In 2017 a copy was put up for auction and was expected to fetch 1500 to 2000 AUD. It’s realised price was not released at the time, but by now the book was sadly out of my reach. The Book was extensive-

ly illustrated with Earl’s paintings whilst the Seacraft articles written by Mick Morris and illustrated by Earl, whether in col-our or black and white, were all printed in grey scale excepting one, which was on the cover of the May 1949 edition depicting rounding the Cape of Good Hope.

TEDDY

On her arrival back to Sydney in 1948 Kathleen and her crew were given a hero’s welcome and awarded a lot of space in both the yachting and secular media but not so Sirius, the first Australian yacht to circumnavigate 1935-37, that received but muted recogni-tion. (Kathleen was thus the second to do so).

Sirius, a 62’ staysail schooner owned by the Nossiters, an estab-lished Sydney yachting family, was launched early in 1935 and, af-ter limited shakedown cruises, departed Sydney in July of the same year. Her crew on departure was Harold Nossiter Snr, Harold Nos-siter Jnr, brother Dick and a family friend. Dick would be the naviga-tor having gained his Yachtmaster’s Certificate in 1933 in prepara-tion for the voyage. By the time Sirius arrived back in Sydney in May 1937 Dick was an accomplished navigator.

Back in Australia Dick joined the Royal Australian Navy Volunteer Reserve and Commissioned

as a Sub-Lieutenant. With the outbreak of war in 1939 he was seconded to the Royal Navy

where he served on trawlers and corvettes on convoy duty in the North Atlantic and the dreaded

Murmansk run. He commanded a corvette and was de-mobbed with the rank of Lieut-

Commander.

In 2010 Dick, a few weeks short of his 100th birthday would receive a belated OAM which would

go well with his DSC previously awarded for bravery during the war.

LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

One aspect of cruising that always produces a range of views and explanations concerns the technicalities of anchoring. Which anchors for various situations, what scope of rode relative to the depth of water, and for which types of boats. Greg has put together a summary of the phys-ics of anchoring that can help us to see the science behind the practice. Like all seamanship skills, the science has to blend with experience, and the benefit of a group like ours is shared experience of different situations, different localities and different boats.

The Physics of Anchoring: Practical Application

Greg Barnicoat, Escapades

This article examines the physics of anchoring for a boat in moderate conditions due to gusting

winds and waves. It applies to both sailing yachts and motor boats.

Summary:

The forces on the chain and anchor

How to estimate the wind drag on a yacht

The importance of chain weight

Simple formula relating wind drag, water depth and length of chain

Simple chain length to water depth ratio eg 5:1 is unreliable in winds above 20kts.

In my analysis, I have used three references that contain a considerable amount of mathemat-

ics and physics. In this document I have provided the results with as little maths as possible.

Ultimately, most of us will work out rules of thumb that work for our boat in various conditions.

http://alain.fraysse.free.fr/sail/rode/rode_b.htm

https://www.awelina.co.uk/anchor_rode/rode_length.html

Civil Engineers Reference Manual, 6th edition by Michael R. Lindeburg- catenary formulas.

Equipment

Anchoring equipment consists of an anchor and a

rode connecting it to the boat, normally at the

bow. Diagram A below is a fish-eye view of an

anchored boat.

L = the scope of the rode in metres.

H = the height of the bow roller above the seabed

in metres, and

F = the horizontal force on the anchor chain

caused by the effect of the wind and sea on the

boat.

The wind force or drag on the boat is measured

in deca-Newtons (daN). 1 daN = 9.8N

Note that 1 daN is nearly equal to the force ap-plied by 1 kg of mass (0.98 daN).

Anchor Holding Force

I will not consider the pros and cons of different anchor types, but instead provide some infor-

mation that applies to most anchors.

When the anchor is properly set it should be buried in the sea bed.

Many anchor tests show that the holding force of an anchor when pulled horizontally is approx-

imately proportional to its weight, but is also affected by the following factors:

Bottom type (rock sand mud) etc.

Anchor design. Some modern anchors of the same weight can outperform older anchors

(eg CQR) by a factor of 2 or more.

Diagram A

PAGE 14 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

Typically, a 15 kg anchor will give a holding force of 500 daN in soft clay and over 1000 daN in

mud. Many anchor manufacturers and yachting magazines provide holding force data, so you

may be able to get more accurate information. The following links compare anchor holding

power in 2006 and again in 2018-19.

https://newcontent.westmarine.com/content/documents/pdfs/WestAdvisor/2006-Anchor-

Tests.pdf

http://www.anchorright.com.au/downloads/Robertsons-TATS-AnchorTestChart.pdf

https://www.mysailing.com.au/news/testing-the-new-generation-of-anchors

Angulation.

In light winds a portion of the rode will lie on the seabed, but as the wind strength increases the

rode will be lifted off the seabed and eventually the anchor will be pulled somewhat upwards.

This is called angulation. Most anchors will tolerate an angle of about 8° with a loss of holding

force of about 10%.

Angulation of more than 10° may cause the anchor to lift out of the seabed.

So, in setting the anchor it is important to know the wind force that will just lift all the rode off the

seabed.

Rode

Most boats attach a chain to the anchor as an all rope rode will usually result in anchor

angulation and offers little resistance to chafing on the seabed. Anchor chain is described by its

maximum working load (due to force) and its weight per meter.

The use of chain and nylon rope in strong gusting winds will be considered in Part 2.

Static Situation with only chain as the rode

The physics of a boat attached to the anchor by a chain with little or no vertical movement gives

the following results.

• The shape of the curve of the chain does not depend on the weight of the anchor.

• The horizontal force on the boat due to wind and current is transferred to the anchor via the

chain. The chain laying on the seabed offers little resistance unless it is wrapped around

something like a bommie.

• The curve of the rode that hangs in the water is called a catenary. The catenary is described

mathematically as y = C cosh(x/C).

• The shape of the catenary depends on:

The chain length and the height of the bow above the seabed; and

A factor referred to as C, which is the ratio of the horizontal force divided by the rode

weight (m) per metre in sea water C = F/m.

Since steel is about 7.7 x the weight of water, the weight of the chain (in air) must be reduced by 13% in sea water. That is, weight of chain in air x 0.87.

How does the chain function?

As the wind forces the boat away from the anchor it must lift the chain, and this takes energy. The chain stores this energy and as the wind abates the weight of the chain will pull the boat back towards the anchor. The chain acts somewhat like a spring and the heavier the chain the more energy it can store. Consequently, the energy stored in the chain depends on the horizontal force acting on the boat and the weight of the chain. This factor (C) is akin to the spring constant (force divided by extension) that we know as Hookes Law.

LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

Boat Forces

Wind Drag

This section applies mostly to sailing boats, both monohull and catamaran. In a static situation

the boat pulls the chain with a force caused by wind drag. The force on an individual boat is

proportional to the wind speed squared. The drag on the rigging is significant because the wind

speed increases with height above the sea. The American Boat and Yacht Council uses the fol-

lowing formula to calculate the wind force on a sailing yacht:

x ) daN for a monohull, and

x ) daN for a catamaran.

Where L is the boat length in meters and V is the wind speed in knots. The force does not de-

pend on the boat’s displacement. Remember that deca-Newtons can also be visualised as

equivalent to kilograms of mass. Here are some examples for three yachts.

V 10 20 30 40 kt

10m Yacht 41 163 366 651 daN

12.8m yacht 57 228 513 912 daN

12.2 m cat 101 406 913 1623 daN

Other effects on the boat caused by waves, surging, yawing and veering will also increase the

force exerted on the anchor chain and will be considered in Part 2.

Current

For modern cruising yachts the force of a 3kt current will normally be less than 100 daN and is

the same as the force needed to propel a boat at the same speed. Note that the tide of more

that 3kts will often cause the yacht to lie at an angle to the wind.

The following link has a calculator for estimating the power required to propel a boat at various

speeds in the displacement mode:

http://www.kiwiprops.co.nz/cms/index.php/resources-general/vesselspeedcalc

Critical Force

When anchoring we want to know how much chain should be let out for the expected wind

strength as the anchor provides the maximum holding force when pulled horizontal to the sea

floor. Therefore, we want to know the critical force that just lifts all of the chain off the seabed as

any greater force will start to lift the anchor shank. See the red chain in Diagram A.

The length of chain, L can be calculated as follows: L ≈ √(2xHxC),

Where H is the height of the bow roller above the sea bed, and the factor C is the ratio of the wind drag force (see table above) to the weight of the chain (in water) per meter. C = F/m.

Note that the chain length depends on the square root of the water depth and critical forces

and is not a simple ratio.

As a consequence, a simple rule such as ‘4 times the depth of water’ is not accurate for all

conditions and depths of water. There are also other calculations that can be completed

for the relationship between water depth, wind speed and chain weight for a given boat.

For most of us however, using the table above and the equation L ≈ √(2xHxC), it is a

simple matter to draw up a table for our own boat that shows how much chain to put out

in various conditions. This will be explained further in the next instalment (editor).

PAGE 16 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

Did you know that in the 18th century a seaman could be hung for keeping a log or diary that

attempted to record the ship’s track and position? The Royal Navy was so afraid of mutiny that

keeping a personal log was an automatic sentence of death. This attitude led to the loss of life

for many, and it is claimed that in one incident near the Scilly Isles

it led to the loss of over 2000 crew and four ships. It happened like

this:

On the morning of October 22, 1707, five warships under the com-

mand of Sir Clowdesley Shovell (you couldn’t invent a name like

that) was returning from Gibraltar and was lost in dense fog. His

navigators could not decide on their exact position, and legend

has it that a seaman with a local fishing background approached

his Captain and suggested that they were much closer to land

than thought. According to the story, Sir Clowdesley promptly had

the man hung for mutiny. By the end of the day four ships had struck the rocks to the southwest

of Lands End and promptly sank. The flagship Association struck first, followed by the Eagle and

the Romney and then the Firebrand. Sir Clowdesley might have had time to regret his arrogance

before being swept onto the beach, where a local woman is supposed to have promptly relieved

him of his emerald ring. It was events such as this that became a catalyst for the development of

an accurate chronometer to enable navigators to calculate their longitude, although one wonders

how Sir Clowdesley’s navigators would have taken a sun shot at midday in dense English Chan-

nel fog. The story is told as fact in an older (1995) publication called Longitude: The True Story

of a Lone Genius… written by science reporter Dava Sobel, and is worth reading if you can lo-

cate a copy. (Currently available through Dymocks for $19.99 and Amazon).

If you have read any interesting books during lock down, would you like to write a few words of

review and send them to me to share through the Cruiseletter?

Sailing Yacht Florence

In the last Cruiseletter I mentioned two online video blogs that I thought worth watching for their

Aussie sailing content. People who don’t use scantily clad ladies to sell their blog, but do show

their audience some interesting sailing and interesting destinations. I invited you to email me if

you have found any interesting vlogs that you think are worth a look. One such is a young British

couple who visited Australia at the end of last year on their way around the world. Their video

blog can be found here https://www.youtube.com/watch?v=-QwNIOpE0wU where they are currently in

Thai waters not far from Phuket. Stunning anchorages and good sailing - definitely worth watch-

ing.

PAGE 17 LAKE MACQUARIE YACHT CLUB CRUISING DIVISION

LMYC CD Calendar of Events – 2020 & 2021

NB: All Committee and General Meetings are held in the Bridgedeck Room at LMYC. Start times

are 4 pm for Committee and 7.00 pm for General meetings. On water activities will generally

start on the Friday and finish on the Sunday. Coffee mornings start at 10.15 am - shared be-

tween LMYC and western side of lake - check Facebook for details.

Sadly, all organised CD events are cancelled until the Coronavirus distancing

rules are rescinded.

A date is now set for the 2021 Pittwater Cruise: 14 - 26 February at Pittwater.

Date Event Comment

2020

11 May General Meeting Guest Speaker: CAPT Malcom Goodfellow

15-17 May Lake Cruise & Soup Day. Lake Mac: Co-ordinator -

Rathmines Catalina Festival Next festival is 2021

25 May Coffee Morning Co-ordinator: Krackt. Location:

25 May Committee Meeting

TBC LMYC AGM

8 June General Meeting Guest Speakers:

12-14 June Newcastle Cruise

29 June Coffee Morning Co-ordinator: Krackt. Location:

29 June Committee Meeting

TBC Float Your Boat Dress up your boat on Lake Mac.

13 July General Meeting Guest Speaker:

17-19 July Explore the North Location: Lake Cruise, Co-ordinator:

27 July Coffee Morning Co-ordinator: Krackt. Location:

27July Committee Meeting

10 August General Meeting Guest Speaker:

14 August Skills Day Lake Mac Cruise, Co-ordinator:

31 August Coffee Morning Co-ordinator: Krackt. Location:

31 August Committee Meeting

5 September LMYC Sailing Season Opening

14 September General Meeting Guest Speaker:

18-20 September Cruise – Shared meal at Brown’s Bay

Co-ordinator:

28 September Coffee Morning Co-ordinator: Krackt. Location:

28 September Committee Meeting

12 October General Meeting Guest Speaker

16 - 24 October Ivan Irwin Cruise Locatioon: Lake Mac; Theme

26 October Coffee Morning Co-ordinator: Krackt. Location:

26 October Committee Meeting

Date Event Comment

9 November General Meeting Guest Speaker:

13-15 November Cruise to Port Stephens Location: Lake. Theme:

30 November Coffee Morning Co-ordinator: Krackt. Location:

30 November Committee Meeting

14 December Christmas Party LMYC Marquee – Starts at 1800 hrs.

31 December New Years Eve Cruise Location: TBA

2021

11 January General Meeting

25 January Coffee Morning Co-ordinator: Krackt. Location:

25 January Committee Meeting

26 January Australia Day & Family Outing Co-ordinator: TBC Location: Black Jack’s Point

8 February General Meeting Guest Speaker:

12-14 February Monthly Activity Location & Co-ordinator: Seeking a Volunteer

February Coffee Morning Co-ordinator: Krackt. Location: TBC

February Committee Meeting

14 - 26 February Annual Pittwater Cruise NEW DATE

27 February Sydney Harbour Mini Cruise

6 March LMYC Commodore’s Charity Ball

8 March General Meeting & AGM Guest Speaker: Nil due to AGM To be confirmed

CD members are reminded that participation in CD activities is entirely volun-

tary. It is the responsibility of the skipper of the vessel to ensure that the ves-

sel and crew are adequately prepared for the conditions that might occur

during the activity.