Concerned about putting foam in a boat and holding water

[CFrankum]

Hello, I have an 18’ flat bottom boat that I am doing some work to. I will be putting in a floor and want to use aluminum, but I’m a little concerned about putting foam boards underneath because this boat will primarily be used in saltwater and will get wet inside frequently. It’s for duck hunting so getting in and out with wet waders and we wade fish so same story year round in and out of the water into the boat.

So I’m worried that saltwater will get underneath the floor and hold in the hull and start to corrode the bottom. Is the warranted or if I wash down the boat every time as I plan to it shouldn’t be a problem? Or is there a way to seal the foam up more that it won’t contact the water and therefore won’t hold any water? The boat does have good drainage with the strakes but I’m still concerned. The back 4 feet of the boat won’t have any foam at all where the water will eventually collect but there will likely be water draining down to the hull at the front then make its way backwards.

Thanks!

 

[mbullen]

Closed cell foam boards won't hold water to begin with. Placing the boards so that the original hull channels will continue to offer drainage is key.
Pour-in, two-part foam is a different animal and I would suggest avoiding that stuff.

One could always take a few small pieces of your proposed material and do a little experimenting first. Submerge a piece for a while in a pan and see how it does.