JMichael said:
Thanks bassboy1. That explains a lot of what I found when I recently removed my floor, and why. "Traps dirt" is an extreme understatement, if what I found in mine is common. :lol: I only found one small area (approx 6"x14") with any pitting so it sounds like I was lucky there.
I don't want to hijack or derail the OP's thread, so could you PM me a link to any info on alternative routes to go if we want to maintain the safety factor of the foam flotation but avoiding the negative aspects of this. Thanks for the reply on this and any other info you can provide. I'm almost ready to replace my floor, so now would be a good time to find out as much as I can on this.
I'll post it in the open forum, so others can read it as well.
There are two ways to provide adequate flotation without hurting the aluminum. One is air space. On many welded boats over 20' (over 20', for two reasons), the deck is often fully welded, and pressure tested, with the area below serving as flotation. I helped build a 25 footer with this style last year.
The reasons this method is only used on boats over 20' are: first off, and most importantly, the US government mandates that boats 20' and under have 2 pound per cubic foot density flotation foam. Secondly, seal welding the decks on a boat under 20' is no easy feat, given the thickness (or lack thereof) of the aluminum used on the smaller boats. One could probably count on one hand, possibly with fingers left over, the number of builders in this country who could build a 14' boat, out of .080, with seal welded decks, and not destroy the boat with warpage.
The second way, and this is most practical on the smaller boats, is to mold the foam outside of the boat, and encapsulate it with fiberglass, or a heavy plastic and tape. Then, (and don't forget this part), install it with spacers, to allow water and air to flow between the bundle and the metal.