Rwgreen2384

I am replacing stringers on a 24 Python and the foam was the original culprit of the rot. Mainly because the foam was not properly done. I understand 4lb density is what to use and poor slowly but I have no idea how much to get. Thank tank is about 6 feet long 2 foot wide and 8 inches deep. It has about 1 1/2 gap all the way around that needs to be filled.

Speedracer29

I'm getting ready to do one myself, I ordered a 16lb (2 gallon) kit of 4lb density and it expands to roughly 4 cubic feet. The 4lb (2qt) covers 1 cubic foot, which wasn't enough for my application, and it was cheaper to buy the one big kit than 2 small ones.

From everything I've read and heard, you want to mix it in small batches (1qt-ish), quickly mix and pour it around the tank at the corners first. It will bind to itself as additional pours are added, but working time before expansion is only about 45 seconds and it needs to be poured in 70-75* temperatures for correct expansion. I'll be using plastic mixing containers from the local paint shop to mix/pour.

Anything you don't want covered needs to be taped off and covered with plastic drop cloths, and you will need to secure the tank with a bunch of weight on top of the tank or braces across the tank to prevent it from rising as the foam expands. Acetone will clean it up while it's still wet, but apparently once it's dry mechanical removal is the way to go (bread knife). Also, to prevent crevice corrosion, coal tar epoxy on the tank is widely advised. Any water trapped between the foam and bare aluminum will rot the tank.

Good luck. This is one project I don't want to do again, so I'm making sure I do it right.

Bondo

Ayuh,..... I Hate foam, 'n Hate foamed in tanks even worse,.....

If yer gonna foam it in, be sure to allow limber holes so everything can drain to the pumpable bilge, or you'll be back replacin' rotten wood again,....

I prefer to build a tank cradle to support, 'n secure the tank, with straps, 'n thin rubber strips,....

ICDEDPPL

iTrader: (1)

That`s what I did.. no foam.
Support and 1/4" rubber strips.

Speedracer29

What, and miss out on all this fun?! Puhlease!

(Off topic question- what's the pink stuff? Is it... Bondo?)
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f_inscreenname

Every boat I've restore that has a foamed in tank the tank gets replaced because they are always full of holes. When replaced I never use foam being it was the cause of having to replace it in the first place. Coal tar the tank, install with rubber strips to keeping it off the deck and stringers leaving a air gap between the boat and tank and use blocks to lock the tank to the boat. Simple and have seen it work first hand for 50+ years in other boats. Foam will trap moisture and not allow for expansion and contraction of the tank over time.