# drawing midship section of catamaran

Discussion in 'Boat Design' started by shrijeet mishra, Apr 1, 2020.

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1. Joined: Apr 2020
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### SuhasJunior Member

So from your scantling calculations, you will get a min required thickness based on the section modulus of the stiffener you are trying to design. Thickness in FRP depends on the layer sequence you provide it. And thickness of each layer depends on the glass content and method of fabrication. You get these values from Chapter 7, Page 14 equation for thickness.
So if you are using a CSM of 300 GSM from that equation youll likely get a thickness around 0.6mm.
For example:
If I have a sifffener of Size: 60(H)x40(B)- Layering:2xCSM300. Then its thickness will be 2x0.6=1.2mm.
You need to stack up these layers to meet your section modulus.

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### SuhasJunior Member

I work at Navgathi Sreejith. Its near CUSAT .
Since this is your final year project, Id suggest you to make your own model from scratch. It'd be a good opportunity to learn hull modeling and fairing. Will prove to be helpful in future.

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### rxcompositeSenior Member

It is the poles that makes the ship stand.

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### TANSLSenior Member

Thanks Rx, I'm sure Ad Hoc knew about it but couldn't remember right now. Now he can rest, uffff .... thank goodness!
In these deep, intellectual and scientific discussions, a little humor is always welcome.

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### shrijeet mishraJunior Member

thank u so much sir fo rmaking me understand
ill try learning and getting it done in soft copy.

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Well, those are the only 'stands' that I know of, that you cite.

But Tanls appears to know, or think he knows, of another:

So if it is NOT those poles/stick/stands to support the hull of a model or during construction....what is the "calculation" being referred too?
I simply have no idea...which is why I asked the question. But of course... no clarification.

Why do posters use terms they do not understand merely to appear/sound knowledgeable eludes me...

At least you replied...many thanks RX

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### TANSLSenior Member

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I could not agree more.

You cannot answer a simple question based upon clarifying a terminology that you used, no one else, yet you cannot supply the definition of the term.
Just endless misdirection obfuscation and trolling...

Pathetic!!

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Ive found these online too:

Tailor made for the job. No need to calculate.

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### shrijeet mishraJunior Member

suhas sir
shall i proceed with these dimensions in excel to draw like the reference drawing i got

if have some time and if possible can you guide me with your rough drawing if any changes are required.?!
thank you

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### gonzoSenior Member

I think you still have a fundamental error on this design. If it is a fast catamaran, the displacement should be reduced dramatically. Another major problem is the very wide and flat stern that is submerged. That will generate a huge amount of drag that will make it impossible for it to be a fast boat. Also, the beam is too wide for a fast displacement hull. If you need it to have a large beam, it should be a Vee bottom so it can plane.

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### shrijeet mishraJunior Member

sir ill cross check it over once again.

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### Niclas VestmanSenior Member

Dear Shrijeet
If I understand correctly, your main subject of study is structural engineering. And that you have not yet focused on hull shapes, hydrodynamics or seakeeping. Correct me if I am wrong.
I am just an amateur myself, but I would like to agree with the experts who have mentioned that your general design should be abandoned and totally redone.
Take a look at the designs of a recognized skilled naval architect with expertese in multihulls. His 85' power cat has very similar traits to your requirements. Scaled down 10% and then make the bridgedeck 3m narrower. That will yield a 24m x 8m, 1m draft, 20 tonne lightship with 20 tonne payload, 30 knots capable semi-displacement cat.
Well, I for one love his designs... Good luck with your project!
Kurt Hughes Multihull Design - Catamarans and Trimarans for Cruising and Charter - 85' Term Charter Catamaran https://www.multihulldesigns.com/designs_stock/85powercat.html

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### Niclas VestmanSenior Member

Kurt Hughes Multihull Design - Catamarans and Trimarans for Cruising and Charter - 61' Catamaran Ferry https://www.multihulldesigns.com/designs_other/61ferry.htm

This narrower 65' design might be even closer yet, to your SOR. Same designer. (Yes I am a fan of mr Kurt Hughes' designs ). Just keep in mind that he often makes quite light designs with thourough structural engeneering that requires the builder to be careful to not ad extra weight. My guess is that those designs could very well be heavier and require more displacement, if drawn/enginered by someone else. But that is just my amateur guess.

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