anyone tried using the pink or blue board from the big box store in lieu of the 2 part expanding foam for flotation? pro’s, cons ?
It has definitely been used, with mixed results. The question is why?
Apart from being cheap and readily available.
If you were building a raft to float over from Cuba then its probably suitable.
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A cubic Ft. of air floats 64 lbs of saltwater 62 lbs of fresh water. That’s 12”x 12x 12” equals 1728 cubic inches.
Foam flotation comes in many forms.the best is closed cell foam so its air bubbles do not absorb moisture.
Styrofoam, mixed poured foams, cores all work to varying degrees without holding much moisture.
Plastic bottles work great in a closed section but the space around them does nothing.
Air chambers need to be airtight to work. Coast Guard rules say you cannot use the hulls sides to form air chambers.
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my reason is I’ve re done a number of hulls only to find the flotation waterlogged, even on one high end skiff and was even more surprised at how little of the product was used. I read the pink board is rated for below grade use in construction with claims it will not absorb water.was thinking about putting the pink board in plastic bags, ty-rapping and sealing with duct tape. thank you Chris-Morejohn for the detailed explanation.wonder how effective any of it is.
just to clarify, wasn’t questioning Chris-Morejhns explanation, appreciate the education as he explained, just wondering how effective foam flotation is
How effective foam is for doing what exactly..?
My thoughts on this would be to build air chambers on the bottom of the cap to qualify them for USCG approval.
Waterlogged foam is definitely a thing especially when directly touching the hull skin bottom. Anyone that worked on old boats has experienced it. I tore one down that someone has filled with white styrofoam sheets, in a trash bag. That to was a huge mess.
I’m not sure how or what your build will be, but on my last one, I went with linerless floor. (No false floor) I built a flotation compartment into the very front of the bow, filled with pour foam. Then poured foam under the rear deck and both gunnels. After trimming the excess I then painted them with a rubberized undercoating.