Flotation Foam Compartment?

[ccx2]

Hey All, im soon to the point on my Garvey build where i will be filling compartments in the seats, bow and stern, with foam. Ive seen on here somewhere about advice as far as venting the space or not , painting or not, what do you all suggest? The plywood spaces will be coated with epoxy then foam put in then sealed airtight with the seat tops glued in place. I dont think painting the inside would be necessary.
Am i on the right track
Also, epoxy coatings that are out of sunlight and hard to get to to paint, like under seats along the keel where lumbers are cut to drain water aft under the seats, is paint necessary?
Thanks.

[Pernicious Atavist]

If they are sealed, you don't need foam. Foam does not add flotation, it only displaces water in an otherwise wet area.
And you're right--epoxy not exposed to sun is okay.

[BBSebens]

If they are sealed, you don't need foam. Foam does not add flotation, it only displaces water in an otherwise wet area.
And you're right--epoxy not exposed to sun is okay.

What he said. all the foam does is keep water out if the chamber is compromised. Its an effort to make a boat harder to sink. (we all know there is no unsinkable boat.) can't hurt to throw some bilge primer on it, but imho, its not necessary.

[Ian McColgin]

I'd use CPES as opposed to a thinned down gluing epoxy. If you use a paint or coating at least somewhere outside that's vapor permiable, as epoxy is, and if you're confident that you can pour the foam on a schedule that leaves no voids, no need to vent the compartment. Note that many pros even of wooden boats encapsulate and seal foam. It'll out-gas a little in the sun and may breath in a little when cooling, but the wood can handle the very modest flex this involves.

All the problems with moisture intrusion around encapsulated foam that I have personally seen are retrofits, not new construction, leading to incomplete bonding of the foam to wood that's not well sealed anyway. This leads to voids in the chamber where vapor can condense and the rest is history.

G'luck

[Chip-skiff]

I just opened decked-over compartments in the bow and stern of a skiff that showed evidence of moisture accumulating: slight checking in unsealed plywood, with rust and staining around screws and the bolts holding the rudder gudgeons.

The boat is a trailer sailer in a relatively dry climate, and has never been on a mooring. Which I take to mean that the wood inside any "sealed" compartment ought to be protected with some sort of primer or epoxy coating. Which I'm going to do, along with new bronze screws and bolts.

In cold weather, any water vapour in the air trapped in a sealed compartment will condense and wet the exposed surfaces. So if the air is humid when the compartments are sealed, you can have a semipermanent problem with moisture.

Or so I imagine, from the evidence at hand.

Foam or some sort of space filler would decrease the amount of air, thus reducing potential moisture. But it also makes maintenance work more difficult.

[floatingkiwi]

You have a distinct, precise and easily understood way of putting things Ian.
Thanks mate.

[TerryLL]

If the chambers are air tight I would forget the foam, but I would have an access port in each chamber for air-out and inspection. These plastic hatches are easy to install.

Available from Jamestown Distributors.

[ccx2]

Thanks All, Coast Guard regs say that if the compartments are on the hull and not on interior bulkheads on all sides you have to foam them, or so ive been told. I was thinking about doing it as TerryLL says but i have to use foam so it will be done Ian's way, but, i have plenty of epoxy on hand and dont want to buy the cpes for the small bit i would use, wouldnt unthickened epoxy be ok? unpainted.

[Ian McColgin]

By all means, use up the epoxy. CPES sinks into plywood better than anything and is a superior preservattive - causes cancer in rocks - but unthinned epoxy will do the trick. Even though the amine blush of curing epoxy inhibits bonding with paint, I have not seen that it noticably bothers the extent to which expanding foam bonds to whatever it touches.

G'luck

[DDan]

Thanks All, Coast Guard regs say that if the compartments are on the hull and not on interior bulkheads on all sides you have to foam them, or so ive been told. I was thinking about doing it as TerryLL says but i have to use foam so it will be done Ian's way, but, i have plenty of epoxy on hand and dont want to buy the cpes for the small bit i would use, wouldnt unthickened epoxy be ok? unpainted.

I believe the reasoning behind this is that compartments on the hull can be "holed" in an accident. Without foam, you'd have no flotation if this were to happen.

[ccx2]

I believe the reasoning behind this is that compartments on the hull can be "holed" in an accident. Without foam, you'd have no flotation if this were to happen.

Correct.

[Tom Robb]

Do the coasties have anything to say about foam/no foam on inland waters? I'd have thought they would not. If you never get on their radar I'd go with sealed-no foam and deck plates to vent them when laid up. Why add a place for rot trouble.
An other method might be removeable blocks of foam, if foam it must be, so you can let the wood dry out. As someone may have mentioned, nothing keeps water vapor out 100%.
If getting holed in an accident is a reasonable possibility, a sinking boat may be the least of your troubles.

[SchoonerRat]

Inflatable bags can give you a margin of safety if the hull integrity is compromised. Unlike foam, they can be easily removed when the boat is stored.

[Gary E]

Floatation?? Garvey ??? in the same subject???
You must be building a flimsy lighweight version made from cardboard or tissue paper or somethin..

All Garvey boats made in New Jersey never had any such thing and they all floated, even in winter time after the duck hunters put a couple 12ga blasts through the bottom... geeze what whimps this generation has become...

[Arko]

Inflatable bags can give you a margin of safety if the hull integrity is compromised. Unlike foam, they can be easily removed when the boat is stored.

And you can make your own cheaper than you can buy.
http://www.halkey-roberts.com/samples.htm On this page you can request free samples of their products. I got some of these , http://www.halkey-roberts.com/moreinfo.asp?pic=4&ID=173 and I had some heat sealable nylon from Seattle Fabrics and used it to make some float bags that I use for my SOF kayaks. The valves work great. I used some LOCtite No Mess Adhesive to seal them to a length of some clear vinyl tubing and into the bag. I think I saw a link to the instructions on here recently. I got some of these too, http://www.halkey-roberts.com/moreinfo.asp?pic=4&ID=148 and they work real well too and I like the way they look.
This is a really good site with some applicable products for some projects.