# Infusing with a wood female mold

Discussion in 'Fiberglass and Composite Boat Building' started by Jetboy, Mar 11, 2014.

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### TANSLSenior Member

It may be interesting to consider the bending moments experienced by a catamaran hulls.

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### peterengSenior Member

Hi Jetboy,
Firstly you can use design codes such as ABS, Lloyds, GL and others as a design basis. Some of these are not intended for trimarans but if you study the maths behind the numbers you get an idea of the intent and the design factors involved eg vertical accelerations so at least you have a starting point. Then there is experience which tempers some numbers, then for tri beams the minimum condition is the addition of the sailing loads and the static loads in say upwind, downwind, spinnaker and reaching for instance. If you are into fea you can drop the boat from given heights and establish what happens in the structure. eg I've attached an avi of a barrel being dropped into water as an example. We can see the stresses or the decelerations in the impact. For instance if I model the boat I can do this to simulate a pitchpole from a given velocity. Cheers Peter S

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• ###### cylinder test 1.avi
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### TANSLSenior Member

Jetboy, all Classification Societies have separate rules for calculating monohulls and multihulls. Thus. if you see any rule not intented for trimarans, do not use it. Use of multihulls.
Precisely the CS rules have the advantage that, even if you do not have the concepts, you can calculate the required scantlings. For many years, and even still today, designers of multihull (not racing) use these rules without using FEA or videos. So my advice is you take a regulation of the CS that best suits your needs and read it carefully. You can immediately check that all questions are answered there. Everything I say, I repeat, is valid for "normal" boats.

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