# motoryacht design

Discussion in 'Boat Design' started by lopese2, Feb 23, 2009.

1. Joined: Dec 2008
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Location: design

### lopese2Junior Member

Hy
I’m student
I design a motoryacht using maxsurf but I need to know if my hydrostatic at DWL results are correct and if they are accepted by the safety regulations.

Displacement 57.9 tonne
Volume 56520312122.2 mm^3
Draft to Baseline 1100 mm
Immersed depth 1097.4 mm
Lwl 25265.4 mm
Beam wl 6434.9 mm
WSA 124116116 mm^2
Max cross sect area 4323844.7 mm^2
Waterplane area 98014767 mm^2
Cp 0.517
Cb 0.317
Cm 0.614
Cwp 0.603
LCB from zero pt 9388.4 mm
LCF from zero pt 9996.2 mm
KB 723.2 mm
KG 0 mm
BMt 4347.2 mm
BMl 54306.7 mm
GMt 5070.4 mm
GMl 55029.9 mm
KMt 5070.4 mm
KMl 55029.9 mm
Immersion (TPc) 1.005 tonne/cm

2. Joined: Aug 2004
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Location: Trogir, Croatia, Europe

### KresoJunior Member

Hi !

Safety regulations require GMt, but you didn't give KG (KG 0 mm) so Maxsurf GM isn't real. !
GMt=KMt-KG !!! :!:

You must predict or calculate KG of your motoryacht design.
Good luck

3. Joined: Dec 2008
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### lopese2Junior Member

but i would like to know how can i calculate KG for the motoryacht
thanks

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### KresoJunior Member

You are student of naval architecture ? If you are I'm sure you talked about calculation of center point...
If you don't have much time you can predict KG with percent of height. Attach sketch of your design with given height and I'll give you KG.

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### lopese2Junior Member

Sorry but I’m not a Naval Architecture student
I’m CAE student and I have to design and analysis a yacht using FEM tools for my final year project
I’m using Maxsurf to design and Hydromax to help me with the analysis

yacht data
LOA 27700 mm
beam 6996.6 mm
Depth 3777.9 mm
Draft 1100 mm
Displacement 57.9 tonne at DWL

#### Attached Files:

• ###### yacht igs file maxsurf.igs
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6. Joined: Dec 2008
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### lopese2Junior Member

sorry mr Kreso
But I manage to fixe my maxsurf setting and I go KG result
But I still need to know if the results are ok for safety regulations
can u help me
Displacement 58.3 tonne
Volume 56878966682.8 mm^3
Draft to Baseline 1100 mm
Immersed depth 1099.8 mm
Lwl 25269.1 mm
Beam wl 6441.2 mm
WSA 124965042.2 mm^2
Max cross sect area 4399645.6 mm^2
Waterplane area 98184198.7 mm^2
Cp 0.512
Cb 0.318
Cm 0.621
Cwp 0.603
LCB from zero pt -4774.1 mm
LCF from zero pt -4151.3 mm
KB 721.9 mm
KG 1100 mm
BMt 4344.5 mm
BMl 53993.7 mm
GMt 3966.5 mm
GMl 53615.6 mm
KMt 5066.5 mm
KMl 54715.6 mm
Immersion (TPc) 1.006 tonne/cm
MTc 1.237 tonne.m
RM at 1deg = GMt.Disp.sin(1) 4035.8 tonne.mm
Precision Highest 200 stations

7. Joined: Aug 2004
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Location: Trogir, Croatia, Europe

### KresoJunior Member

Hi !
Your KG is to low, my suggestion is to take assumption of cca.0.75 of Depth, that gives for your design KG=2.55m.
For stability check you need to go in Analysis menu , than in Criteria and in Criteria you set on IMO A.749(18) Ch.3 Code on Intact Stability.
Read manual of Hydromax for details.
Ciao

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### lopese2Junior Member

thanks for the help
but 0.75 of depth is not to low for motor yacht
thanks

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### lopese2Junior Member

coefficient values