Sealant for fuel tank cover

[Chaser]

4000UV will stay white better than 4200, plus it pulls and cleans up better.

Whatever you do don't use 5200!!!

For my floor panels I plan to use a compressible foam strip on the flange that the panel will sit on. I'll screw the panel down on top of the foam strip, and then fill the gap on the edge with 4000UV to seal it. That way, when I need to pull it up, its just the seal that needs to be scraped out, and the hatch will not be adhered to the flange on the bottom. Gluing it in on the bottom is asking for damage if you have to remove it at a later date.

[bigeasy1]

I've had to take the fuel hatch cover off several times due to a couple of bad sending units, and another tnat leaked.I had used marine silicone, and although I pretty much think that silicone has no place on a boat, in this case I think its okay.
It does collect dirt easily, but its effective in sealing out water, and when the hatch needs to be pulled, its easy to break the silicones bond.
God help you when you have to break the bond of 5200.When they say its mostly for permanant repairs, they mean it.
Sika corp also makes several marine urethanes under the Sikaflex banner and offer a couple that are considered removable.They may be better suited for your needs

[gofastsandman]

Sika is fine.

[Big fish]

I used GE silicone and had no leaks. It was also easy to remove when I had to check my sending unit.