foam entire bilge (1976 24' Thompson resto)

[garrettp]

I just got a 24' Thompson that had rotten stringers and they where removed before it was traded in. The boat now has nothing other then my minds eye

The gas tanks are on the gunnel and I may do the same with water tanks (if I even put any in).

My question is this. I am going to gelcoat the entire floor with a slope and a water gutter on the sides (gutters kind of already there). For the cabin I am going to lower the floor a step and put in a bilge pump under the steps since I do not want air from the engine compartment getting to the cabin.

So, can I foam the entire bottom of the boat leaving only a bilge are in the engine compartment and a small one in the bow cabin?

I work at a marine shop doing engine service, fiberglass work and gelcoat repairs so the work will be easy enough for me. I am kind of leary about having such a small bilge area but would install 2 pumps in the rear as well as lights on the dash for when they are on. Any water tanks can go on the gunnel or in the rear so no need to run any lines under the floor.

I think I have all my bases covered and after working on boats and tearing out floors and seeing what is under there (and smelling it), I think I want a sealed bilge, save for the engine and cabin.

Thanks for the input,
g

Oh, here are my boats 1976 24' Thompson, 1995 Euroline jetboat (not pictured: 1994 Seadoo GTX and 1985 17' Crestliner)

www.meganjoy.org/images/boats.jpg

 

[jzellers]

Re: foam entire bilge (1976 24' Thompson resto)

Hey G,

I restored a 20' Thompson (7422 Fisherman) several years ago. I foamed all the areas other than the engine compartment, but not all the way up. Mainly this was due to cost because at the time (1996) that foam was really expensive. However, there's no reason you couldn't do so in your boat. It's probably better anyway because it will make your hull more rigid. You have the right idea sealing the cabin from engine compartment bilge - as you probably know that's the way the cruisers are built today.

From my experience, what probably rotted your stringers in the first place was the original foam becomming water-logged and wicking through the coarse fiberglass roving into the stringers. Fortunately the modern closed-cell foam isn't likely to do that. I wouldn't worry about the bilge areas being small. Your cabin bilge will probably never get water in it.

I used treated plywood for my floors so that if any water ever got it it wouldn't rot, but I let the sheets dry for several months before using them. If you're using regular or marine-grade, you won't have to worry about that. Another big issue on the boat I had was that NONE of the deck fittings had so much as a dab of silicone or bedding compound on them. The deck is wood-cored and I spent a lot of time fixing some rot around mounting holes, so that's something you might want to check as well. I ended up removing every fitting and accessory on the topside and bedding it properly.

Joe

 

[garrettp]

Re: foam entire bilge (1976 24' Thompson resto)

Hey G,

.... that's something you might want to check as well. I ended up removing every fitting and accessory on the topside and bedding it properly.

Joe

all ready there . I am moving the gas fills from the deck to the side. I will be doing some fiberglass work to make "gutters" on the side as well and also on the hard top. I just stripped out a 1978 24' Thompson and took some items from that for my boat.

I wondered about the treated lumber shrinking. I will have to try to find some marine material which shouldn't be too hard. One of the owners of Cruisers lives right down the road from me (oddly enough).

As for the foam, I found 5gal on line that will fill 40cu ft for $244 plus shipping. That should fill it about 3/4 up I believe.

Other then that, I have a long way to go. I still need to get the boat off of the trailer and winter is just around the corner . I wanted this thing in the water come spring

 

[jonesg]

Re: foam entire bilge (1976 24' Thompson resto)

Submerge some litre soda bottles in the foam to save moola.

 

[Bondo]

Re: foam entire bilge (1976 24' Thompson resto)

what probably rotted your stringers in the first place was the original foam becomming water-logged and wicking through the coarse fiberglass roving into the stringers. Fortunately the modern closed-cell foam isn't likely to do that. I wouldn't worry about the bilge areas being small. Your cabin bilge will probably never get water in it.

Ayuh,.... Bullship.... Modern Foam is the Same Crap you took out....
There hasn't been any Miracles in chemical engineering discovered in the last 30 years,...
Closed cell foam Still degrades,+ gets Wet...

The hull is 24',.. You Don't need Foam, at All....
Build the hull to support itself,... No reason to rely on Foam,... Use Stringers,+ Bulkheads...
The bilge, ALL of it, has to be able to DRAIN....
Boats live in the Water,... It WILL get Wet under the decking,... Period....