ply bulkheads

[mattoc]

Hi I’m currently designing a 33’ catamaran and have not been able to find information on bulkhead widths so my question to you is this.

What width should my bulkheads be I have the option of 6mm 9mm 12mm or 18mm any information would be of great help

[Raggi_Thor]

I AM A BIT WOORIED,
sorry, caps locks whas not intended though :-)
If you don't know what stiffness you need in your bulkheads, and how many you need, think about all the other things you dont know!
I would say 12mm, will you then use that and go to sea?

[mattoc]

Oh, sorry it does sound a bit “out there” but no Im actually looking at a set of plans, very very old plans, and from researched information there are a lot of new techniques and materials for bonding and strengthening so Im trying to find the best way to approach and alter the designs at hand.

thankyou for your reply

[Raggi_Thor]

I think 12mm would be "normal" for a monohull sailboat of that size, but catamarans are stressed or loaded differently, you have enormous forces from the crossbeams, I guess..

[katfish]

I am building a 42 ft Wharram with West System epoxy, and the bulkheads are 18mm ply. I would think that for a 33 footer, 12mm would be fine. It also depends on how many there are. The Wharram has them about every 5-6 ft.

[djwkd]

im building a 17' shanty boat (wich i intend to call the sea serpent'and intend to have a bulk head every 3 feet,would this be ok?

[Raggi_Thor]

It's impossible to answer simple,
it depends on the skin thickness and longitudinal stiffeners.
With some stringers say 20x20 to 30x30mm and 6 to 9mm skin it sounds reasonable. BUT, it depends on deplacement, speed, conditions etc.