Filling voids

[Graham_Wright]

Is there any reason why I should not fill voids with expanding foam?

The space beneath my stern tube, for example is a wonderful hiding place for dropped nuts and accumulates water which cannot drain.

 

[sailorman]

Is there any reason why I should not fill voids with expanding foam?

The space beneath my stern tube, for example is a wonderful hiding place for dropped nuts and accumulates water which cannot drain.

Do NOT use builders foam it absorbs water, you need closed cell type

 

[Graham_Wright]

Do NOT use builders foam it absorbs water, you need closed cell type

I believe the one I have used claims not to be water absorbent but, in any case, does it realy matter? The space is full of water normally anyway!

 

[sailorman]

I believe the one I have used claims not to be water absorbent but, in any case, does it realy matter? The space is full of water normally anyway!

stick a sponge in the void then

 

[Graham_Wright]

stick a sponge in the void then

So what would that achieve?

Try again!

 

[sailorman]

So what would that achieve?

Try again!

it will soak up water &also stop thing from dropping into the bilge

 

[Tranona]

If you really do want to fill the void, then clean and dry it, build a temporary coffer and pour 2 part expanding closed cell foam in. You could shape the top so that water drains into the bilge proper.

 

[Graham_Wright]

If you really do want to fill the void, then clean and dry it, build a temporary coffer and pour 2 part expanding closed cell foam in. You could shape the top so that water drains into the bilge proper.

Thanks;- that's what I had in mind.

 

[rogerthebodger]

I would also glass fibre over the top of the closed cell foam to ensure it is sealed.

 

[Graham_Wright]

I would also glass fibre over the top of the closed cell foam to ensure it is sealed.

Not being pedantic but what does the sealing achieve? It was wet before, it should be less wet even with the sponge! And, for the same reason, why closed cell?

 

[sailorman]

Not being pedantic but what does the sealing achieve? It was wet before, it should be less wet even with the sponge! And, for the same reason, why closed cell?

closed cell does not absorb water
see #2

 

[rogerthebodger]

Polyurethane foam becomes a soggy mess when wet. Open cell builders foam goes soggy very quickly, closed cell takes longer but can happen. So I would seal it with GRP to try to prevent the foam becoming a wet soggy mess.

This happens to me to a little speed boat I have.

 

[Avocet]

I tried it on a few little voids in Avocet - more for an attempt at noise insulation rather than as a measure against dropped hardware. Even if it's in a normally dry area, it looks scruffy very quickly. There's always a bit of dust off it (unless you glass it in) and if you EVER want to get in there (in my case, I wanted to run a wire through there for a bit of kit), it's a right royal pain in the backside!

 

[rob2]

So there you have it! Closed cell foam, sealed off with a conduit run through it.

Rob.

 

[vyv_cox]

Having some experience professionally, I can advise that no PU foams generally available are completely closed cell. The type of foam used for insulating sheets by the building industry is truly closed cell, but made in very carefully controlled conditions. Kingspan, for example.

Single and double pack foams generally available will absorb water over time. Years ago i filled canoes with two pack 'closed cell' buoyancy. A couple of years later the canoes were many kilograms heavier and didn't float. We had to dig it all out.

If the OP is happy to carry a weight of water about all the time, fair enough. Although this is often a recipe for osmosis in the inside of the hull. Otherwise it would be a sound idea to seal it with grp, as suggested.

 

[Graham_Wright]

Having some experience professionally, I can advise that no PU foams generally available are completely closed cell. The type of foam used for insulating sheets by the building industry is truly closed cell, but made in very carefully controlled conditions. Kingspan, for example.

Single and double pack foams generally available will absorb water over time. Years ago i filled canoes with two pack 'closed cell' buoyancy. A couple of years later the canoes were many kilograms heavier and didn't float. We had to dig it all out.

If the OP is happy to carry a weight of water about all the time, fair enough. Although this is often a recipe for osmosis in the inside of the hull. Otherwise it would be a sound idea to seal it with grp, as suggested.

It is already wet and does not drain so there will be water there for evermore whether it be raw or absorbed in foam. To avoid osmosis (and I share the same paranoia as everyone else) I could coat the receiving area with loads of gelcoat first.

The stern tube is located at its extremities only (allowing me to withdraw the propshaft without dropping the rudder) and the void is beneath it.

 

[GrahamM376]

Years ago i filled canoes with two pack 'closed cell' buoyancy. A couple of years later the canoes were many kilograms heavier and didn't float. We had to dig it all out.

I found the same with a grp tender I built some years ago. Poured closed cell foam into various buoyancy compartments which were grp sealed all around. After a few years the weght gain was noticeable and the outside of the hull in those areas was a darker colour due to absorbed water not being able to evaporate on the inside.

 

[Squeaky]

Good afternoon:

Thanks you guys, I don't know why I read this forum as you lot have just ruined my plans to squirt a lot of foam into the floor stringers which forever seem to be filled with water and now you have poured water on this bright idea.

Oh, well, guess I will have to come up with a new idea to solve the problem.

Cheers

Squeaky

 

[sailorman]

Good afternoon:

Thanks you guys, I don't know why I read this forum as you lot have just ruined my plans to squirt a lot of foam into the floor stringers which forever seem to be filled with water and now you have poured water on this bright idea.

Oh, well, guess I will have to come up with a new idea to solve the problem.

Cheers

Squeaky

Limber holes are there for a reason