tank replacement

[John Vyn]

I just purchased a 31 that has been sitting, basically unused, for the past 8 to 10 years. After new exhaust manifolds, heat exchangers, oil and trans coolers, new carbs, new rudders and a new muffler, I'm on the the fuel tank. I have ordered an aluminum tank from High Tide. Danny has been very helpful. Any suggestions for removing the original, foamed in place tank and what should the new tank sit on (some sort of rubber pad??) The tank is to be Ceram-Kote finished. Does the tank still need a coat of coal tar?

Thanks John

[MarkS]

I put mine on a 1/4" sheet of Lexan. Mine is stainless and needed to be covered in rubberized undercoating. Not sure about the aluminum. Somebody else will chime in on that.

[Pete Fallon]

JohnVyn,
To remove the old tank great some # 19 Malin fishin wire make a wooden handle for each end, remove the aft wood bulkhead behind the tank. Get a cross cut saw with a blade about 3' long, remove all the deck supports and anything else that is along side the tanks. Use the cross cut saw to cut thru the old foam along both sides of the tank, then with another person use the #19 wire to cut thru the foam, starting at the transom end and work forward, use asawing motion with the wire, there are 2 drain tubes under the tank you want to be above them when you start cutting with the # 19 wire. When you get all the way thru to the bow end, borrow or rent a Porter Power hydraulic tool with the pincher jaw adapter, make some wooden wedges to put under the tank whenit start6s to lift. A big shop vac to clean up the ols faom and saw dust. The tank once it starts to loosen will make a awful noise once it starts to let go, Take your time and be careful, make sure you have eye protection and the old wet faom under the tank will sink like ols sneakers, rubber gloves are recommended. Use 2 part 4 pond pour foam whenyou put it back in and rest it on something that will not rot, like strips of PVC board or hard rubber strips to keep it away from the hull at the bottom of the tank, you might have to replace the race ways under the tank, I used 1-1/4" PVC Pipe cut in half and glassed it to the hull with epoxey resin and some 1808 bi-ax cloth. It's not a real hard job just get the correct tools and take your time, it might take a while for the tank to pop after all the cutting is done. I think it took us a six pack before she let loose. ood luck.
Pete Fallon

[John Vyn]

Thanks Pete for the very complete instructions. Capt Patrick also recommends wrapping the tank in cellophane to keep the tank from sticking to the foam. Thoughts. Also how do you keep the tank from rising as the foam expands? Or is the foam only on the sides?

[Pete Fallon]

JohnVyn,
When the tank is in place after the dry fitting, used a couple of wooden or a pvc cleats on either side a couple near the front and acouple near the rear along the long sides of the tank. There shouldn't be enoough foam undr the tank to make it move with the cleats installed.
Make sure to use the 4 pound density pour foam and if you have some coal tar epoxy left over do the tops of where the foam is showing after it cures for a while for added moisture barrier.
Pete Fallon

[Marlin]

I placed a couple of 2x4" under the gunnels,1fore ans 1aft above the tank,ran a couple 2x4" down to the tank secured with some drywall screws to keep the tank from pushing up, when I had finished,there was considerable pressure built up against the 2x4" rentention bracing, wasn't my idea, captain pat again, if and when I grow up, I want to be just as smart as him

[John Vyn]

Well I got the tank out last Tuesday. We removed the inboard floor stringers, used a sawzall with a long blade to cut lengthwise along the tank. I removed the rear bulkhead, but couldn't get the wire started. I later found out there was a "keel" on the tank. So I drilled holes in the four corners of the tank flange. We took the boat the the yacht club crane and tied a bridle through the stern holes and gave it a yank. Up popped the the stern part of the tank, so I made a 4 point bridle and the tank popped our - easy pezy!!! Yesterday I ordered FRP channel from McMaster Carr - 3 1/2 x 1 1/2 x 3/16. This week I'll build all new stringers and supports out of the channel and I'm looking for some cushion between aluminum tank and the hull. Sure is nice to be able to clean under the tank and get the whole aft area hosed down. Tank was definitely bad. When we cut it up, and the baffles had little round pieces of gel coat flaking off. The fiberglass was fine, but the baffles were causing the problem. New tank shipped last week and will be here in So. Calif next week. It will be nice to carry more than about 40 gal of gas.

[Marlin]

There was a post I think by captain pat on tank installation, I cut a sliced of 2" PVC pipe in half and epoxied it under the tank in the lumber line so to speak, this will let u wash from the engine compartment to the aft lazarret ,I placed 4pieces of 1/4" rubber pads to set the tank on then applied the foam in place thing,the foam is your vibration damper and this whole tank installation system will stiffen up the boat, I would not wrap the tank in Saran Wrap ,u then would theoretically need to exert some type downward pressure to keep the tank in place and secure, let the next person figure out how to remove it,u figured it out! My thoughts

[lobsta1]

,I placed 4pieces of 1/4" rubber pads to set the tank on

Correct me if I am wrong, but I've been told repeatedly that rubber in contact with aluminum is strictly a no-no. Something about rubber containing graphite that causes a reaction in the aluminum. Something vinyl or pvc based is fine though.
Al

[John Vyn]

Thanks for the reply Marlin. My new tank only has hull contact for the first 9" from outboard in. The rear bulkhead of the tank was removed, so I have a cavity that is maybe 16" wide and about 6" high. I like the idea of being able to wash from stern to bow, so I've cut a limber hole in the forward bulkhead of the tank area to get the water forward. I went to Harbor Freight and bought the rubber mat used for foot relief in front of work benches. Cut 10" strips and will glue these down for tank rests. Tank goes in tomorrow afternoon or Friday morning.

[John Vyn]

One more thing. I bought the tank through High Tide Marine in Florida. They were great. I asked for the full, vent and pickup fittings to be moved from standard so they landed in the center of the hatches. I also asked for a visual, non electric fuel gauge to be incorporated at the pickup. They found a mechanical / electrical gauge that fit the bill perfectly. All in all a very good experience.