Foam - my expericence
I have used 'great stuff' aka foam in the can, for years.It is not really closed cel, but doensnt asorb too much water, if the foam is not cut. (ie., the expansion was allowed to run normally. once you cut off the 'sealed' ends it does asorb some water, and more importantly it will asorb smells and hold dirt and oil.)having said that, I have used it in my mac 26D.I used it to fill in the voids between stryofoam, and as a glue to hold foam blocks to the sides of the hull.I like the foam peanuts better, as they are easy to remove.-just dont get too confident that the foam will really float to boat upright, should it try to sink.IMHO, i expect my boat to turn turtle and float upside down. hopefully it will still float, after all the other stuff (weigth) I added.ps: i used a bunch of foam noodles in one area, as I often use these to swim, and then store in area for floatation.