Question(s) about replacing the foam/floor in my deep-v

[NeWcS]

So for the past few years I have noticed that my boat has been sitting really low in the water, in the back. After doing some research and talking to a few people; it turns out the foam may be waterlogged. Well today I took out one of the seat mounts and was able to get to a small piece of the foam in the hull. And indeed, it is waterlogged, AF.

I assume I’ll need to take the floor out and remove the old foam. Now, my first question is, and please go easy on me. The foam doesn’t add buoyancy, right? It just makes it so if water gets in the boat it won’t sink, right? Being that the foam isn’t in contact with the surrounding water, it’s not what is keeping the boat afloat, right? Or am I thinking about this all wrong?

Being that I’ll have to cut the floor out to get to the foam, I’ll have to put a new floor in. Do I just use treated plywood for the new floor? Or is there something special I’d want to use?

If anyone has done this type of project and has any tips, picture, links video(s), etc. that would really help. If this isn’t the best place to get help, please let me know a forum or somewhere else to ask.

Thank you!

 

[huggyb1972]

The foam is only needed to maintain enough bouancy to keep the boat at or near the surface in a swamped condition. The boat would float just fine without it.

Is your boat aluminum or fiberglass? I would avoid treated wood for any boat projects. Though I have used it in past with no issues I've ever observed. it's not good for aluminum boats and is supposed to cause corrosion to the hull.

Taking the foam out will be a chore for sure. I've done it a couple times. I tend to use exterior grade plywood because of cost for my old beater boats. The biggest thing will be sealing whatever you use to keep it dry and giving water a way to escape to the bilge easily. One way I did on my aluminum boat was put down a layer of pink construction foam on the hull which doesn't absorb water and also doesn't block the drainage channels, then I put the pour in foam on top of that. After the floor was layed of course plugging the holes for the foam with fiberglass resin. Then I coated the deck board with rustoleum primer then top coat. I had about 5 years on that boat and the floor was still great.

 

[NeWcS]

Thanks for the reply!
It's an aluminum boat. Not sure on the weight. I know the motor (75hp Merc) weights about 300 lbs. I'd guess the boat is less than 1000 lbs.
So you put the new floor in then pour the foam? Or am I misunderstanding?

 

[huggyb1972]

Yeah deck goes in then drill a few strategically placed holes in it and pour the foam in. The foam is a 2 part product that when mixed reacts by expanding several times its original volume and will fill a space rather quickly when done correctly.

 

[NeWcS]

The foam is rated in lbs/density. What am I wanting as far as that goes?
thx for the help!

 

[huggyb1972]

2lb is more for floatation. The heavier types are for strengthing assemblies

 

[tpenfield]

Post up some pictures if you can.

Aluminum boats and foam flotation are a different animal than fiberglass boats and foam flotation.

If you've had wet foam in contact with the aluminum hull, it would be best to inspect for corrosion/pits/etc.

 

[NeWcS]

Post up some pictures if you can.

Aluminum boats and foam flotation are a different animal than fiberglass boats and foam flotation.

If you've had wet foam in contact with the aluminum hull, it would be best to inspect for corrosion/pits/etc.

Once I work up the nerve to start cutting, I'll post some pics.

 

[huggyb1972]

Some advice. Take plenty of pictures for reference and don't destroy anything that could serve as a template for something you are content with just replacing.

 

[NeWcS]

In terms of removing the floor; what should I expect? Will it be screwed down to some supports in the hull or will I need to expect to have to cut it out? I know every boat is different, but what is typical for this style of boat.

This is the make and model of what I am working with. 2001 Monark 160 king sc.

 

[huggyb1972]

The ones I have worked on the floor was riveted down. That's a nice looking boat. I wish I would've kept the smokercraft I had similar to that one. I bought it to repair and sell though, it has a rather large dent in the hull up front it required taking the front deck out and bucking rivets where the sides met the keel. Quite a process nice return though. I'm really growing more fond of aluminum boats especially after doing all this fiberglass work.

 

[NeWcS]

Thanks! My boat is actually better than that in the picture as mine has a 75hp. lol. Thing is a little rocket-ship.
Man, I don't even know where to start. I guess I could pull off the laminate flooring and see what I see.

heres mine:

 

[huggyb1972]

I had a 90 spectrum that was my 1st aluminum rebuild. It was a I/O powered with a OMC Cobra that I had some trouble with. I built a outboard bracket for it and hung a 115hp Merc on it. It was such a better boat after that. I sort of regret selling now. I held on to the money the guy paid for it until mid summer of that year just incase he wanted to bring it back.

 

[NeWcS]

I did some work on it today. I took the laminate flooring off the deck. The wood looks in pretty good shape. My only fear is that there is an aluminum deck under the wood floor. When I took the seat mounts out, I can see there is a sheet of aluminum under the wood. I am hoping it's just part of the inner structure to add rigidity for the seats. I drilled out all the rivets out but am still going to have to use a saw as the deck extends to the side walls where I can't access.
Thanks again!

 

[NeWcS]

So I took the majority of the back floor out and have to say I was pretty disappointed. I was expecting/hoping to find 200lbs+ of water-soaked foam. I didn't. All the foam looks good and had only a few spots where the foam was holding water. There was only a little bit of water in the hull. I am at a complete loss as to what to do next. There is one more area I am going to cut up, but I doubt I'll find anything significant.