Space around fuel tank for foaming
11-02-2016, 04:23 PM
#1
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Thread Starter
Space around fuel tank for foaming
I am about to measure up for a aluminum fuel tank to be built.What I am not sure of is minimum space that is or should be allowed between the stringers bulkheads. Any info is greatly appreciated.Oh and also foam that should be used.
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11-02-2016, 07:54 PM
#3
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Leave 2-3" on all sides of the tank, have it coal tar epoxy coated. Add a drain under the tank (PVC pipe secured with polyurethane adhesive works well). A 16lb kit of 4lb density foam should be enough for a 60-75 gallon belly tank. It mixes at 1.2:1 and starts to kick in under a minute. Having one person mixing and another pouring works well. Some people only do the corners to secure the tank. I put a drain in, filled the cavity, then tapered the foam toward the stern so if water gets on top it drains off into the bilge. You will need to put something across the stringers to keep the tank from popping up when you down it. A couple 2x4s shimmed accordingly and screwed to the top of the stringers works.
http://www.shopmaninc.com/foam.html
http://www.shopmaninc.com/foam.html
11-02-2016, 08:51 PM
#4
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Thread Starter
bck,The boat has a fiberglass tank.which is part of the hull. Actually the tank was fine and in great shape. I just don't trust all the additives fuel companies add these days. Bought the boat and building an engine so I figured change to aluminum while doing every thing. I removed floor and now have to measure.
11-05-2016, 08:58 AM
#6
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Thread Starter
Forgot to ask this. My boat is a stepped bottom (twice) do I have to have the tank stepped or does the bottom get filled with larger amount of foam in the deeper part of the bottom.
11-05-2016, 02:11 PM
#7
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Platinum Member
Speedracer's advice is on the money . Especially the part about 4lb density foam . It sounds like he's done it already himself ! The 2 part foam packs come in different densities and you may have to order the right stuff as what the marine shops generally have in stock is the general flotation foam mix . ( which is the wrong stuff)
Waterproofing the tank first is critical too . Make sure it's spotlessly clean and de-greased first before you put anything on it as a barrier coat .
Locking it down before pouring is really important as well . That foam stuff when it fires off could lift the boat off the ground if it was in the right place .
One other thing , use buckets that resist transmitting ambient heat to the foam mixture . Old wax paper buckets or plastic bleach containers cut open of about 1.5 gallons will be the right size and marginally increase your working time . I recommend small pours first to get under the tank and then increase the mix size slightly to cover the sides , etc . You only get one chance to do this right .
Waterproofing the tank first is critical too . Make sure it's spotlessly clean and de-greased first before you put anything on it as a barrier coat .
Locking it down before pouring is really important as well . That foam stuff when it fires off could lift the boat off the ground if it was in the right place .
One other thing , use buckets that resist transmitting ambient heat to the foam mixture . Old wax paper buckets or plastic bleach containers cut open of about 1.5 gallons will be the right size and marginally increase your working time . I recommend small pours first to get under the tank and then increase the mix size slightly to cover the sides , etc . You only get one chance to do this right .
