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Rod Sampson - School of Marine Science and Technology
Preliminary Predictionof Power
CourseworkMAR2010
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Preliminary prediction of power for:
A single screw bulk carrier 15 knot service speed
The contract requires that on a fully loaded
trial the ship achieves a speed 1 knot greater
than the required service speed with the engines
developing 85% MCP
Plot PE(trial) PE(service)& VSvs
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Vessel Particulars
LBP = 135.34m
B = 19.30m
T = 9.16mCB = 0.704
Enter your speed and
deadweight into
NEWAT2 to obtainthese values
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Vessel Particulars
LBP = 135.34mB = 19.30m
T = 9.16m
CB = 0.704
LBP = 444.03 feetB = 63.32 feet
T = 30.05 feet
CB = 0.704
Take GREAT care with your units
Convertto feet
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Stage 1 - Effective Power Prediction
Objective - use average C values to estimate PEfor trial and service condition
Note:For the C notation you may use
(C), or C
ITTC standard notation is and will be adopted hereCc
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Stage 1 - Effective Power Prediction
Specify a speed range which includes the trial
and service speeds
2kne.g. of the trial speed
Vs(trial) = Vs(service) + 1knot = 16 knots
Vsrange = Vs(trial) 2knots = 14 ~ 18 knots
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It is not important to use exact speed values in knots
Use the range for the speed
This will avoid double interpolation in your
method causing an error.
It is also SIMPLER to use
VsL
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VsL
0
500
1000
1500
2000
EffectivePower(kW
)
0.65
0.700.75
0.80.85
13.69 knots
17.91 knots
Speed units are arbitrary as you need to interrogate
graph both ways therefore USEVsL
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The model data used is the BSRA standard series. It wasgenerated for a standard vessel of:
400ft x 55ft x 24ft
Therefore to use it you must first scale your vessel down
to this size
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Actual ship dimensions
L x B x T = 135.34 x 19.30 x 9.16 [m]
L x B x T = 444.03 x 63.32 x 30.05 [ft]
BSRA ship dimensions
LB BB TB = 400 x 55 x 24 [ft]
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Scale factor
=L
LB
444.03
400= 1.11 = 1.11
LSD BSD TSDL
B
T
444.
031.11
=
L
B
T
=
=
=
= 27.027 ft
= 57.045 ft
= 400 ft
Dimensions
correct for length
63.32
30.
05
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Volume of actual ship ( )
= CB LB T
= 0.704 135.34 19.3 9.16
= 16844.25m3
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O values are now required from Table 2
by interpolation
Actual ship L = 444.03 or 135.34m
135 0.0732
140 0.0726O1 = 0.07320
Scaled down ship L = 400 or 121.92m
120 0.0743
125 0.0739O2 = 0.07406
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Rod Sampson - School of Marine Science and Technology
O values are now required from Table 2
by interpolation
Actual ship O1 = 0.07320
Scaled down ship O2 = 0.07406
1 O2 = 0.07320 0.07406
1 O2 = 0.00086
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Using interpolate for using Table 1VsL
CB
to obtainCc
average
0.65 0.70
0.700 0.694 0.713
0.701 0.698 0.724
0.704 0.6956 0.7174
If you use you do this once for each set,
otherwise you interpolate for AND for
VsL
VsL
CB
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Calculate Lc
Lc=
VgL
4
Lc
= 1.055 VL
(Lc)0.175Finally
knots
Feet
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(Cc)DesignCalculate
Calculate Kc
Kc =V
1
6
4
2gKc =
V
168441
6
4
2g
Kc
= 0.22354 V
(your volume)
(metres/sec)
(Cc)Design = (Cc)400 + [O1 O2] S
c (Lc)0.175
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Calculate displacement
=g = 1025 9.81 16884
=1 .6937 108(N)
(kg)
(large!)
(Kc)2 = (0.22354 V)2 1.6937 108
(Kc)2 = 8463472.7 V2 (metres/sec)
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Total resistance and effective power
RT =
Cc
Design
(Kc)2
1000
RT = CcDesign
8463472.7 V2
1000
PE =RT
1000 V[kW]
(metres/sec)
(metres/sec)
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(1 + x)froude = 0.973
Calculate sea margin
(1 + x)froude = (0.44 + 2.229 [L]1
4 + 10.058 [L]1)1
20
(where L is your vessel length)
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Final Power Prediction
PE(trial) = (1 + x)froude PE
PE(service) = 1.2 PE(trial)
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Assemble data in a spreadsheet
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Plot PE(trial) PE(service)& vs Vs
0
2000
4000
6000
8000
10000
12000
10 12 14 16 18 20Speed (knot)
Po
wer(kW)
PE (kW)
Pe Trial (kW)
PE Service
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A basic report is required for the assignment.
Take 1 speed e.g close to your design speed and
provide a worked example for this speed showing
how you generated the spreadsheet
If you make an error (very easy on this assignment)
the worked example should provide method marks
ensuring a good grade
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End of Section 1