Why no drain in tank cofffin???

[djbinding]

Just picked up a 1984 200XF.  Opened up the fuel coffin hatch and the tank was floating in water.  Later found the aluminum tank had holes under the corrosion on top. So should i make a couple drain holes into the bilge in the rear of the coffin to drain any future water that may leak through the deck plates???

[Capt. Bob]

Two schools of thought here.

One, the tank "coffin" is sealed  to prevent fuel from entering the bilge, hence no drain holes.

Two, drain holes help remove excess water that causes tank corrosion.

My opinion is that you keep the coffin as dry as possible by sealing the hatch cover and having deck plates that allow a minimum (think no) water in. If you need a drain hole then you are allowing too much water to enter to begin with and you need to change/reseal the hatch and access plates.

Just my thoughts.

Good luck.

[djbinding]

I'll buy that opinion.   The boat sat for 3 years.  I'm replacing the plywood under the coffin hatch and glassing it.   And replacing those 30 year old deck plates too.

[fitz73222]

I'll buy that opinion.   The boat sat for 3 years.  I'm replacing the plywood under the coffin hatch and glassing it.   And replacing those 30 year old deck plates too.

Make sure you dry fit the coffin hatch after replacing the coring and make sure it sits flat. Now for sealing the hatch. I recently pulled mine to replace my fuel line and found the tank compartment to be in perfect condition, no wet foam, tank was perfect. The tank was replaced in '95 so I wanted to make sure it would live another 20 years without issues. For prep, I spent a solid week making sure the every single bit of old silicone was removed. I found that a rag soaked in mineral spirits and soaked into the old silicone would soften it and then a scraped the silicone out with a plastic credit card style hotel key, I save them for scraping jobs like this. Once you think you have all the silicone removed there was some skin left of the old silicone so go back with a mineral spirits soaked rag and rub that skin off until it literally squeaks when you are rubbing it. I think a lot of people miss this critical prep step, silicone WILL NOT stick to old silicone and will not adhere correctly unless the joint is spotless. I used clear exterior grade silicone sealer. I ran a 3/8 bead of silicone around the perimeter lip of the deck then dropped the hatch in place, started a couple of screws cross corners to make all the holes lined up and then ran another bead of silicone around the perimeter to fill the gap, wet fingered the joint smooth and made sure there was no gaps or voids. This gave me two layers of silicone in the joint so it will not leak! I then dipped each screw thread into the tip of the sealer tube to make sure the thread were sealed, as you tighten the screws up, the silicone will crawl up the screw and will leave a nice bead of silicone under the screw head to completely seal it off. I found it was easier to let the silicone dry and go back with a razor blade to clean up the excess sealer displaced by tightening the screw than trying to wipe it off while it was still wet and smearing it everywhere. I'm satisfied that this hatch is sealed correctly and the method worked. PREP, PREP, PREP is the key!!!

[wingtime]

My 1981 200 XF had a 1" drain hole in the aft end of the coffin.  Not sure why yours didn't have one.