Water absorbing foam below deck

[rking453]

Hey folks,

I'm looking to start a discussion about foam underneath carpeted plywood decks on aluminum boats.

A few years ago I bought a 1996 Starcraft in rough shape for $750. Not only were the plywood decks rotted but the foam underneath was completely saturated with water. It was a labor intensive project, but I pulled hundreds of pounds of foam out before redecking. Since then I have not owned a boat with foam in it.

Fast forward to today, I have the opportunity to buy the exact same year and model of boat, but in much better shape. The carpet is original but still looks really nice. The current owner stores it under a lean to, covered.

Despite it looking to be in such great shape, I'm a little apprehensive to purchase given my past experience with the water-logged foam.

Let's say I check over the boat thoroughly before purchase and find it isn't waterlogged. How cautious do I need to be to avoid the foam soaking up water? Should I be worried about fishing while it's raining out? Do I need to store it indoors all of the time, or will a good cover protect it enough?

I'm not sure whether the last boat's foam got completely soaked from a few rain events, or years of being left out without a cover.

What has been your experience with this foam? How easily does it soak up moisture? I really appreciate any advice or experience you can share.

 

[FuzzyGrub]

My expierence with water-logged foam was in a 1967 Starcraft. It was my first floor replacement. I replaced the water logged foam, but stupidily, kept the dry foam. That old foam has now taken on water, and deck needs to be replaced again.

It became our camp fishing boat. When we were not there, it was pulled up on a trailer and plug opened to drain out any water. It was covered most of the time. When we were there, it would be docked, and we would get some heavy rainstorms such that the water would be at the level of the floor. It would get pumped out the next day. So, I would say, once it has deteriated, it doesn't take much to become water logged.

 

[JL8Jeff]

Anything older like that will probably absorb water. My 2001 Lowe sits in the water all season with a bilge pump to pump out rain but when I pull the boat at the end of the season it will drip water out for a couple of weeks. So I'm sure the foam is absorbing it.

 

[rking453]

So what I'm gathering is, unless I want to re-deck it, I should avoid this type of boat? I would really like an aluminum deep-V for fishing, and occasionally pulling kids on the tube. My budget is under $10k so anything I find is going to be around 20-25 years old it seems.

 

[LDUBS]

Any 26 year old boat might likely have issues. You say the boat is well maintained, the flooring looks good (no soft spots?), and it was stored under cover so the foam hasn't been sitting in water. If I liked the boat and thought it was best I could get for my budget, I would go for it. Just be aware you aren't buying a new boat and some repairs might be needed.

 

[Vol423]

Polystyrene foam (the white stuff) will absorb 70-90% of its volume. Polyurethane about 5%. The USCG mandates polystyrene in the bottom 2" next to the hull because polystyrene won't melt in gasoline. I would ignore that and use all polyurethane if you're going to replace foam. Or get a boat over 20' long and the USCG has no purview and no flotation needed. But it will sink if flooded.

 

[thill]

Go see the boat. Grab the tongue and lift. If it weighs a ton, and you think it's waterlogged, walk away unless you want to do the project. If not, buy the boat, enjoy, and keep it covered.

I hope it works out well for you.

 

[poorthang]

my boat was so heavy it sagged the trailer springs. i removed all the foam, piled it up in the pasture. a year later, it wouldnt burn. now i can grab the hitch and wheel it around . much lighter. and safer! just build the cost into your offer. trust me, they know its soaked, it lost mph and handling and they cant pull it with the lawn mower any more.

 

[airshot]

All boats have foam flotation, mandated by the coast gard...when it gets old it becomes a problem, no way around it....

 

[Ironhorse2022]

As far as replacement foam goes, I would think that closed foam sheets (like home insulation 4x8 panels, would not absorb water. Is this true ? If so, seems like a good rebuild option.

 

[MrGiggles]

You can't really get away from it, as mentioned, any boat under 20' is required by the coast guard to have flotation foam, regardless of type or material.

My 84 Tracker evidently spent some time outside uncovered, long enough to rot the deck, floor, and carpet. At some point it was pulled onto the trailer and covered. While I was redoing it, I was concerned about the foam as well, but it was bone dry and still in good shape so I left it all as-is.

I have seen some people use foam board for flotation foam. It can be difficult to fasten and requires a lot of trimming to conform to odd areas. You don't want it to rip up your decks if you get swamped.

I have also seen guys use pour in foam, and "cast in" old pop bottles to help fill the volume. That seemed like the best option to me.

 

[AlanT]

As far as replacement foam goes, I would think that closed foam sheets (like home insulation 4x8 panels, would not absorb water. Is this true ? If so, seems like a good rebuild option.

I seem to remember the USCG doesn't recommend polystyrene because of the interaction with gas and oil. Someone please correct me if I'm wrong. I've done some quick searches in my area for EPP (Expanded Polypropylene), but haven't yet located a good source.

 

[cyclops2]

With out a ACCURATE determination of what foam is really in there ? You are just guessing about floatation being any good. Your guess is just that. Water usually runs to the back & will soak any OPEN CELLED foam there. Test it there if interested. IF wet foam is found ? Hundreds of pounds of dead weight is possible.
Your call.

 

[LightMetal]

I've always wondered if there were air bladders or something else that could substitute for foam. I like Giggle's idea of filling containers with expanding foam. Maybe just find the right type of container that could be fastened down.

 

[InSaneFisherMan]

2021 Boat builders handbook - Floatation

 

[Bob_esper]

It's not just older boats having the issues. Hundreds of new tracker boat owners are also having trouble with it.

 

[thill]

When I did a boat years ago, we used 2-litre and other bottles with the lids screwed on tightly and secured them with shots of fill-foam. Worked GREAT. We didn't have to cut any foam, and we packed them in all the areas that had previously been filled with waterlogged fill foam.

Interesting was the fact that neither gasoline nor cleaner affected the bottles or the foam, but we didn't do it for 30 days, like in the manual posted by Dale. That was a number of years ago, but it was like a completely different boat after all that weight was removed.

 

[InSaneFisherMan]

One of the issues with closed cell foam is when it is for structural support, like a floor.

When you walk on the floor, the cells can crack. Add water and any freezing temperatures and more cells can crack. Open cells are sponges.

Never owned a boat with foam on the floor, but never had an issue with foam becoming a sponge. Some of the foam would start descengrating and need replacing.

 

[LDUBS]

I've always wondered if there were air bladders or something else that could substitute for foam. I like Giggle's idea of filling containers with expanding foam. Maybe just find the right type of container that could be fastened down.

Your post reminded me of an issue I posted a couple years ago about a boat mfg not meeting USCG flotation requirements. They added big boxes of flotation foam to the deck. Kind of ruined the utility of the small boat. I notice the model is no longer on their website. Klamath makes great boats. It is too bad they tripped up on this model.

Here is a link if interested:

USCG Recall of Klamath 152 Westcoaster

 

[InSaneFisherMan]

I've always wondered if there were air bladders or something else that could substitute for foam. I like Giggle's idea of filling containers with expanding foam. Maybe just find the right type of container that could be fastened down.

I've owned a few fiberglass boats that had no foam. I believe they used the air in the double hull design for flotation.

Boat builders handbook has some info on air chambers.