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1978 21 Ft Fuel Tank


noacktexas
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Hey All!

This is my first post (except for the introduction), so not sure this is the correct forum, but here goes anyway.

The previous owner of the boat complained of water in the fuel. I pulled the deck cover off, and exposed the fuel tank. Sure enough, it had a whole in the top (about the size of a bullet hole). The tank is encased in foam, and the foam is saturated with moisture. I pulled the foam off of the top of the tank to fully expose it. I started trying to remove the foam around the side of the tank, and its also completely saturated with moisture. Is it possible to pull out the fuel tank ? Im guessing it sits on top of more foam (which im sure is saturated as well). Any tips on removing the tank would be appreciated. Also, is all of the saturated foam a major problem ? 

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Yes, the tank can be removed.  Yes, it is encapsulated in foam.  The foam hold the tank in place and also acts as an adhesive.  To pull the tank out, the bond between the foam and tank has to be broken.  Some members have used a pressure washer to blow the foam out; it is fast but messy.  The other method is digging it out with any implement that will fit between the tank and coffin box sides.  For the bottom, get a cable saw or similar tool to run along the bottom.  Rig up something so you can run some ratchet straps around the tank and over some 4x4 resting on the gunnels and apply pressure.

i am guessing the tank in the boat was bare aluminum and not coated.  Wet foam against bare aluminum is not good.  If you get a new aluminum tank, coat it with coal tar epoxy to prevent further corrosion.  If you can source a comparable poly tank, no corrosion issues to deal with.

Hope this is enough to get you started.

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  • 4 weeks later...
  • 1 month later...

Sorry didnt see this reply, yes chainsaw worked perfectly, the mess was easy to vacuum up with the shop vac. The tank actually had several holes in it, really bad shape. Regarding the tank, im wondering if anyone has any recommendation on a specific tank model. The fittings on the tank seem somewhat unqiue on this boat, as compared to what im seeing while shopping around. Just wondering if anyone has done a tank swap, and which model tank did you get ? :)

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For an original replacement, check with Florida Marine Tank in Henderson, NC.  I think they were the OEM builder and would have the plans for an exact replacement.  Other than that, you could take your tank to a local certified aluminum fabricator and have it duplicated.  Next option is try to find a Moeller Marine plastic tank that is close to your coffin box dimensions.  

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  • 6 months later...

Thanks for all the input here!

I finished installing a 39 gallon plastic marine tank into the coffin. Next question I have is what is the proper way to reseal the coffin ? It looks like the previous owner used window caulk to seal the cover. Any recommendations on how to reseal it properly ? Thanks in advance! 

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I would go with either BoatLife sealant or 3M  4000 sealant.  Depending on how wide the gap is between the lid and deck, you may want to stuff a piece of foam backer rod down into the bottom of the joint so the sealant will be around 3/8 to 1/2" thick.  Also think about running a piece of heavy mono line (80# or heavier) at the bottom of the joint so the sealant will be applied over top of it.  This way, if you ever have to remove the lid again, grab the mono and pull it up, cutting the sealant and making removal a lot easier and faster.

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