Re: More thoughts on foam in rebuilds.........
JasonJ said:
I've always been a pro foam person. Foam can add structure depending on density and the way it was poured. Foam, even closed cell waterproof foam, can evenually start to take on water. Usually the boats that have waterlogged foam are also decades old, and have not been well cared for. Sealing screws that go through the floor, covering the boat in the winter and when not in use to keep water out, things of this nature dramatically increase both the life of the foam and the entire boat in general.
I myself place the life of the people on my boat as well as my own life far ahead of how long a boat lasts, so foam will always be in my boats. I just do what it takes to prevent the almost inevitable water intrusion.
I agree with you strongly on this point Jason, Using the proper amount of foam in a boat (small) could very well be life saving, one can only hope no one would ever have to second guess themselves in a precarious moment on the water. What's that old saying "There are no Atheist's in a fox hole"
As to structure, there is no one size fit's all theroy here. Does 2lb provide structure no, does 4lb probably not, now 8lb yes it does as well as 16lb.
You can take that even futher, if you properly measure out the cavity between the floor and the hull (sq ft) and drill vent's or holes for foam expansion, fit your floor in place and then pour the foam in allowing it to expand until it flow's out from your vents, you will not only gain strenght from the foam (4lb and up) but you will also glue the entire floor to the hull. Foam bond's extremely well to both wood and glue it will become almost one unit.
Here's some old pic's, the floor was laid down, holes were pre drilled and the edge's were 1/4 short of the wall's. I just kept pouring until the foam expanded first from the oval vents to the outside edge's ensureing a tightly compacted expansion. The guide you see against the wall held the floor down to keep it level and futher compacting the foam.
As you can see the foam came up the middle and out the side's, i doubt very much if there are any void's, it expand's with quite a bit of force, but it also glued that entire floor to the hull and vice versa.
Now she's sealed and glassed in, you'd have to jump on it to feel how rigid it is, just like concrete but i did use 8lb.
Now rot is always a concern so i did fully encapsulate the stringer's in glass, and shot the entire hull-stringer with a bed liner type of material. Will it rot........ yes someday but not in the next ten years or so and if i take on a few big swell's and thing's dont go well, i will stay with the boat. Strictly a opinion here Your milage may vary........8)