Foam filled ply for sole

[blakey1973]

Can I use this product for my sole if I use 1/2 inch or should i use 3/4 it is foam filled with okoume top layers. This only weighs 23#for 1/2in per 4x8 26 for3/4 sheet compared to Merranti A/B BS1088 at 49# for 1/2 or 71# for 3/4.

[frosh]

I would strongly favour the foam composite ply version. The use of the solid ply mainly provides much extra weight and very little extra mechanical strength nor any noticable stiffness increase. Whether you use half or three-quarter inch probably depends mainly on the unsupported span dimensions. That is what sort of framing is under the sole, and what are the separation distances of that framing? If you are not sure, go with the thicker, as the weight and cost difference will be fairly small.

[blakey1973]

Originally Posted by frosh

I would strongly favour the foam composite ply version. The use of the solid ply mainly provides much extra weight and very little extra mechanical strength nor any noticable stiffness increase. Whether you use half or three-quarter inch probably depends mainly on the unsupported span dimensions. That is what sort of framing is under the sole, and what are the separation distances of that framing? If you are not sure, go with the thicker, as the weight and cost difference will be fairly small.

Thats what i thought the biggest span will be about 4ft by 20 inches over the fuel tank . the only spot with out good support.

[frosh]

Hi, I would personally use the thicker one because that fuel tank is a fairly large unsupported span.

[SamSam]

I would wonder about the durability of the foam panel used for a sole. The ply looks to be 1/8" or less. That would flex under a persons weight and crush the foam and soon render the whole works worse than useless. Dropping an anchor on it would easily poke a hole.

Aside from that, is that stuff a commercial product and what does it cost? What sort of foam is it? Is there any structural specs on it?

[blakey1973]

Foam Core Plywood

3mm Okoume faces.

Polyurethane foam core.

Light weight.

Thermal insulation.

This panel is good for bulkheads & other applications where weight is a factor.




13mm 19mm 25mm

4x8 115.00 160.00 195.00

per 4x8 23lbs 26 lbs 29lbs


this is supplied threw Boulter Plywood. Marine ply.. I would cover this with 2 layers of glass probably 1700&1708

[lazeyjack]

depends on the modulus and weights, high density foam, is used under winches, lesser for soles you really ought to call the foam makers there is a crowd in NZ called high modulus , do a google, they seem know it all and supply the foam for many a yacht

[SamSam]

It depends on the foam. If you can easily dent it, it won't work. The glass will help some but also add weight. What sort of boat are you using it on? What is the normal use for the stuff?

Whoever sells it or makes it would be the best place to ask if it will work for what you want. It would be nice for everyone here to know how it works, if it works fine, people could then use it. If it doesn't work and you make a complaint, whoever sold it to you isn't going to care what anybody here said.

http://en.wikipedia.org/wiki/Structural_insulated_panel

Originally Posted by blakey1973

Foam Core Plywood

3mm Okoume faces.

Polyurethane foam core.

Light weight.

Thermal insulation.

This panel is good for bulkheads & other applications where weight is a factor.




13mm 19mm 25mm

4x8 115.00 160.00 195.00

per 4x8 23lbs 26 lbs 29lbs


this is supplied threw Boulter Plywood. Marine ply.. I would cover this with 2 layers of glass probably 1700&1708

[mike steiger]

Hey Blakey,

I agree with Sam on this,if you do not want to use 3/4 fir ply which I think would be fine, I would then suggest going with Coosa blue water 20. Keep in mind that Coosa is expensive. I would go with 3/4 fir ply and Two layers of mat on the underside on each panel, once installed on a bed of 3M 5200 I would then apply a couple of layers of 1808D.B.90 deg and you will have a very strong floor. Once again all of these problems that occur with rot in wood are due to improper sealing when fixtures ans fittings are installed.

[wet feet]

I would agree with Frosh but with a supplementary question.Of all the places to save weight in the boat,why choose the sole?I could understand a light sole for decks above the waterline on a large vessel.