What sealant for FG bulkhead?

My cockpit/day-hatch bulkhead got tweaked in the surf along the hull. The lower seam seperated, and of course flooded the hatch if there was water in the cockpit. I repaired the fiberglass seam from inside the hatch, but the other side, in the cockpit, it has a clear silicone sealer all around and I need to repair a bit of it. I had to remove some of this “clear caulk” and was wondering what to buy to repair it? Will this stuff stick to itself? Do I have to remove it all? (It is tenatiously difficult to remove!)

Any suggestions?

The boat is an Impex Assateague if it matters.

lexel, Sikaflex, 3M 5200, marine goop, any marine sealant that isn’t silicone.

remove the old if it’s not well stuck.


Thanks Steve
I am off to the store to get some 5200 quick set stuff. Any tool suggestions for spreading the bead of say an inch or so? Any application hints would be greatly appreciated. What is left of the stuff is very well attached.

I think water leaked in under the seam, froze and expanded and weakened the glass seam. I was able to pull some of the glass out by hand. I cleaned everything up, sanded, glassed with 4 inch tape and sanded again. Should be strong now, but I do not want any more water to be able to pool under and around the seam.

latex gloves
and your finger. you can make a nice smooth seam with 5200. don’t be afraid to use plenty, in fact the whole tube as any left won’t last long. I’d recoat any rough spots on any of the other b/h’s as well.

good luck


Does the finger dipped in soapy water trick work on the polyurethanes like it does on silicone?


When i used 3M 5200 to reseal the bulkhead on my capella, i just used a normal caulking gun for spots i can get it into, a big syringe from walmart pharmacy for spots i can’t get the big cauling gun into, and a finger in a glove to smooth it all out,no soapy water or anyhing. I’d suggest Nitrile gloves instead of latex because they tend to be tougher, Also, if you’re fussy about looks, take some 2’’ masking tape and mask the hull about 1.5’’ from the seam, peel the tape after the stuff begins to initially skin but well before it dries. Peel towards the seam, not away from it,if possible,for cleaner looks(learned that from the painters at our bodyshop)

Masking cannot hurt as 5200 is pretty
tenatious …

ATTENTION finger users and recommenders …

Use the backside of a big table ( not tea) spoon for a cleaner more consistant bead …

Creates ‘edges’ @ either side of fillet while it ‘spoons’ excess off @ the same time. Then can also be flipped over to swipe off excess on either side of fillet, just have a rag or a few paper towels ready.

The spoon also gives you much more reach and dexterity when doing a front cockpit bulkhead.

If you get the bead right there is almost zero to wipe off and your hands ( and everything you touch ) never get sticky.

With practice one can purposely VARY the size of the fillet on one continuous stoke … cannot be done with constant radius tools or finger ( unless you use pinky ).

A good example of a use for this would be above poster. Some goop still in there, some not. Might need a heavier bead to seal old stuff still there but a nice, clean smaller one where nothing is. O.K. Nobody is going to do this but me … but CAN be done.

Steve is right on the 5200, use it all up on the boat of house / boat once you open it. Sealing all four sides of fore / aft bulkheads should use almost a full cartridge anyway.

No need for soap
While I haven’t tried it with 5200, when working with Lexel or Goop (or silicone in non-boating applications only), moistening a finger with plain water or saliva is all that’s necessary.