the effect of a muddy bottom on ship control
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www.shallowwater.be. The Effect of a Muddy Bottom on Ship Control. Guillaume Delefortrie, jr. expert nautical research. Contents. Nautical Bottom Experimental Research Simulations Conclusions. Contents. Nautical Bottom Experimental Research Simulations Conclusions. - PowerPoint PPT PresentationTRANSCRIPT
The Effect of a Muddy Bottom on Ship ControlGuillaume Delefortrie, jr. expert nautical research
www.shallowwater.be
Contents
• Nautical Bottom
• Experimental Research
• Simulations
• Conclusions
Contents
• Nautical Bottom
• Experimental Research
• Simulations
• Conclusions
Nautical Bottom: confined conditions
deep confined muddy
Nautical Bottom: general definitions
Under keel clearance (h-T)/T
Depth hDraft T
Nautical Bottom: mud levels
1200 kg/m3
1150 kg/m3
33 kHz
210 kHz
Depth?
Nautical Bottom
= the level where physical characteristics of the bottom reach a critical limit beyond which contact with a ship’s keel causes either damage or unacceptable effects on controllability and manoeuvrability (PIANC)
-> applicable to any bottom
Nautical Bottom
= the level where physical characteristics of the bottom reach a critical limit beyond which contact with a ship’s keel causes either damage or unacceptable effects on controllability and manoeuvrability (PIANC)
-> applicable to any bottom
Nautical Bottom: physical characteristics
Fluid mud
Consolidated mud
210 kHz
33 kHz
Water
Interface
Bottom
Critical limit
Mud rheology depends of many time dependent factors and is difficult to monitor
Nautical Bottom: density criterion
Fluid mud
Consolidated mud
Water
Interface
Bottom
occured at a density level of 1.15 ton/m³ or more
ZEEBRUGGE
Nautical Bottom
= the level where physical characteristics of the bottom reach a critical limit beyond which contact with a ship’s keel causes either damage or unacceptable effects on controllability and manoeuvrability (PIANC)
-> applicable to any bottom
Contents
• Nautical Bottom
• Experimental Research
• Simulations
• Conclusions
Experimental Research: overview
Choose relevant ship and bottom types (Zeebrugge harbour)
Build mathematical model for ship manoeuvring simulator
Validate the critical limit with the pilots
Experimental Research: variables
– 3 ship models
– Bottom conditions:
Layer thickness: 0.5 m - 1.5 m - 3.0 m
Mud density: 1100 - 1250 kg/m³
Mud viscosity: 0.04 – 0.33 Pa.s
Under keel clearances: -12% to 21% (interface)
-> artificial mud layer
Experimental Research: towing tank
Contents
• Nautical Bottom
• Experimental Research
• Simulations
• Conclusions
Simulations: mathematical model• STEP 1: 4 quadrants harbour manoeuvring model with a single set of
coefficients for each bottom and ukc condition
• fast-time: the computer performs calculations without human interaction
• real-time: human interaction allows the user to perform a wide range of harbour manoeuvres
Simulations: fast time
0
2
4
6
8
10
12
14
16
0.8 0.9 1 1.1 1.2 1.3 1.4
h1/T (-)
Be
ha
ald
e s
ne
lhe
id (
kn
)
vaste bodem 1.5 m slib E 1.5 m slib F 1.5 m slib G 3 m slib G 0.75 m slib H
1.5 m slib H 3 m slib H 0.75 m slib B 1.5 m slib B 3 m slib B 0.75 m slib C
1.5 m slib C 3 m slib C 1.5 m slib D
Under keel clearance (interface)
Sp
eed
(kn
)
• Advance speed at “harbour full” (66 rpm)
Simulations: real time: trajectories
Starboardside berthing
WATERBOUWKUNDIGLABORATORIUMBorgerhout-Antwerpen
RealTimeSimulatieOpvaartScheurnaarkaai205
Conditie:0Vaartnr.:070Datum:2004-04-28000
M582
Plotinterval20.s Schaal1:/20000.
WATERBOUWKUNDIGLABORATORIUMBorgerhout-Antwerpen
RealTimeSimulatieOpvaartScheurnaarkaai205
Conditie:0Vaartnr.:053Datum:2004-04-26000
M582
Plotinterval20.s Schaal1:/20000.
Portside berthing
Arrival at Zeebrugge, OCHZ Terminal
Simulations: real time: trajectoriesArrival at Zeebrugge
APM Terminal
WATERBOUWKUNDIGLABORATORIUMBorgerhout-Antwerpen
RealTimeSimulatieOpvaartScheurnaarkaai207
Conditie:0Vaartnr.:021Datum:2004-04-19000
M582
Plotinterval20.s Schaal1:/20000.
WATERBOUWKUNDIGLABORATORIUMBorgerhout-Antwerpen
RealTimeSimulatieAfvaartvankaai205
Conditie:0Vaartnr.:067Datum:2004-04-27000
M582
Plotinterval20.s Schaal1:/20000.
Departure from Zeebrugge, OCHZ Terminal, portside
berthed
Simulations: real time: evaluation
Un
der
keel
cle
aran
ceto
inte
rfac
e (%
)
Density (t/m³)1.1 1.15 1.2 1.25 1.3
-15
-10
-5
0
5
10
15
20
25
30
35
d c b f
h
g
e
SCriterion: controllability of 6000 TEU with 2x45 ton bollard pull
• STEP 2: Include the under keel clearance effect above a solid bottom:
• STEP 3: Extend this effect to take the muddy bottom into account using a fluidization parameter
Simulations: mathematical model
L)T,ξ.f(h,FF deep
21 Φhhh*
h h1(N)
h2(N)
h1(N) h1
(N)
= 1
≤ 1
= 0
h*
Simulations: fast time
0
1
2
3
4
5
6
7
8
9
0.50 1.00 1.50 2.00 2.50 3.00
Sliblaagdikte h2 [m]
Ein
dsn
elh
eid
[m
/s]
h/T = 1.10 h/T = 1.125 h/T = 1.15 h/T = 1.175 h/T = 1.20 h/T = 1.30
Spe
ed (
m/s
)
Mud layer thickness (m)
Under keel clearance
• Advance speed at “harbour full” (66 rpm)
• Real time: to be performed (bow thruster effect)
Contents
• Nautical Bottom
• Experimental Research
• Simulations
• Conclusions
Conclusions
• Muddy areas: the nautical bottom is the level where physical characteristics of the bottom reach a critical limit beyond which contact with a ship’s keel causes either damage or unacceptable effects on controllability and manoeuvrability (PIANC)
• Advantages: – Optimised dredging– Admittance of deep drafted vessels– Without jeopardizing the safety
QUESTIONS AND ANSWERS ONThe Effect of a Muddy Bottom on Ship Control
Guillaume Delefortrie, jr. expert nautical research
THANK YOU FOR YOUR ATTENTION
www.shallowwater.be