How to calculate wood width?

[stonedpirate]

Hello,

I am going to build a stitch and glue boat and was wondering how to choose marine ply thickness?

Is there a calculation to determin strength require or bending ability?

Just not sure what to buy.

Thanks

[alan white]

The question seems out of place. On the one hand, if you have designed the boat yourself, you already know enough to decide the ply thickness, but on the other hand, if you are using purchased plans, they should specify ply thickness.
Plywood thickness is chosen based on a huge number of design considerations. Boats are built light and fast or heavy and slow and everything in between.
Let's say you're designing your own boat. If you look at the specs for ten boats in the same size range you'll notice a large difference in weight between them. If the ten boats are made from plywood, you'll see the lightest has a hull thickness of perhaps half that of the heaviest.
I suggest you provide more information. Drawings would help. Intended use would also help (racing, fishing, planing, drifting, paddling, or what have you).

[stonedpirate]

Thanks a lot Alan.

Good points.

So it is a trade off between speed and strength.

I'm not interested in going fast.

I am trying to build an 8 foot indestructable hull capable of circumanavigation like the one below:

[TeddyDiver]

You can get http://www.amazon.com/Elements-Boat-...9480735&sr=1-3

[PAR]

Ferro cement . . . and a serious education in yacht design, plus a good dose of structural engineering . . .

[stonedpirate]

I read it was a stitch and glue.

Might just by some ply and kick it to see what it can handle

Trial and error.

[alan white]

For something like that, two layers of 3/8" plywood maybe, offset by 30 degrees? Wood would give some insulation.
I feel seasick already.

[gonzo]

Remember a watertight compartment for the crack.

[wardd]

that would also make a great coffin

[daiquiri]

How do you pee and poo in that thing?

After few weeks in that box your backbone will hurt you for the rest of your life, I think...

[Manie B]

Gonzo have you been drinking?

Remember a watertight compartment for the crack.
And the power supply for the concrete, you really bowled me over
very good keep it up

[gonzo]

Are you willing to start a manufacturing plant in SA?

[stonedpirate]

Somebody has to beat Serge Testa.

[Manie B]

Are you willing to start a manufacturing plant in SA?

It could be done that was my job
but your financiers / investment team will hate me
I have headed a number of feasabilty studies in my life (= a reality check)
and when i rain on their parade they get VERY pissed off (call me negative)
years later they thank me - usually at the "yot club"

[stonedpirate]

Poms and south africans.

i dont know..