How thick csm for my cabin?

[elioti]

Hi there, i,m extending the cabin on my 34ft motorboat, how many layers of 450g csm should i use, need to walk on the top on it after! Cheers

[TeddyDiver]

Without any warranties: Knees and bended beams, Marine grade plywood and 450g one layer, Marine paint on top. Sole GFP is way too heavy...

[elioti]

Its was originally done in grp, is there such a weight issue? Thanks for reply

[TeddyDiver]

It's allready a quite high cabin so any additional weight high on the boat is.... at least unpleasant, and in the worst case dangerous. DIY laminations tend also to be less rigid and heavier. Anyways it's also easier done with ply and GRP cause no mold is needed..

[elioti]

Thanks Teddy, well have already started laying over ply, have done three layers already, was planning on taking the ply out afterwards, do not think the boat will be top heavy, is a heavy lay up and the engine that may go in weighs over a ton, not sure what to think now..

[TeddyDiver]

do not think the boat will be top heavy, is a heavy lay up and the engine that may go in weighs over a ton, not sure what to think now..
Ok! it will work, except every ounch is out of loading capacity...