www.ultimatehandyman.co.uk

Hello!

I am Planning on changing out The floor in my 17ft motorboat, The original 12mm thick Laminated plywood floor has rotted and I want to replace it with Aluminium tread plate,

However, I'm now wondering how thick of a plate i need to use, in order for it to not bend under weight.

The floor is supported by 10cm wide beams going across The boat, these are spaced 50cm apart
The floor is narrower at The front and gets wider at The back, The widest point is about 155cm
The plate Will be secured to each beam in multiple points with Bolts, fat rivets or point welds (havent quite decided yet).

I'd like to do this with a single sheet because that would make it completely waterproof (boat has self emptying design), alternatively use two sheets and have a seam in The middle of The boat.

I have found a local seller that supplies sufficiently large sheets of EN AW-5754 Tread plate in:
3, 4, 5 and 6mm thicknesses, with 1.5mm tall patterns.

What thickness of plate do I need for the floor to be solid enough to not bend while walking around on it?

Why not ask the seller, since they have knowledge of it?

Experiance at work using Ali Durbar for bits of decking for access ladders and occasionally on lift car roofs would suggest 6mm overall would be good.

Suggest you check the weight per square metre vis a vi the ply that’s there.

Ali will corrode as well especially around salt water especially as durbar plate is not normally anodised.

I'm a bit late to this one but:-

Could Phenolic Board be used instead? It is the stuff that is used on the platforms of scaffold towers. Obviously water resistant and has an anti-slip finish.

As to where to purchase in a large sheet and whether cut edges need treating?