Sealing bulkheads with Lexel

So after two years I’m replacing the Lexel on my bulkheads. This time I’m only going to apply it to the one side of each bulkhead. My older CD Storm has 2.5" foam bulkheads seated within a 1/2" thick foam edging. After warming the boat in the sun the old Lexel pulled off fairly easily. With the Lexel applied to only one side of the bulkhead I hope to avoid the bubbling that I experienced last time. Any other advice appreciated.

How flexible does the join have to be?
How flexible is Lexel after it ages? Maybe you need a new material. It bothers me that the Lexel is easy to remove.

West G-flex has excellent, long-lasting adherance, but even though it is flexy for an epoxy, it might not be flexible enough for bulkheads.

The old Lexel seemed quite flexible
I thought the Lexel had hardened, and I’m sure it did compared to fresh Lexel. In colder weather the old Lexel felt fairly hard. Warming the boat in the sun on a 70 degree day made it rather soft again. I think the adhesion was perfectly adequate even though I was able to peel it off. This time I’ve popped the bulkhead out and will allow it to dry perfectly, then I’ll push it back in and apply the Lexel over the seams on one side. Lexel is so soft (bubble-gum like) when fresh that bubbling was a problem when (presumed) moisture was trapped inside the bulkhead and expanded in the sun. I would not want to try the relatively rigid G-Flex epoxy on a plastic boat.

You want to bond it to the boat, too
Friction and a thin bead of sealant on one sides is not enough to secure a bulkhead adequately. Pressure buildup and rough conditions could dislodge it if it’s not bonded better than that.

What I would suggest is to mark the location of the bulkhead on both sides, remove it, then spread Lexel over that entire area. When you push the bulkhead into place, most of the Lexel will end up on one side. A quick swipe with a moistened finger will turn the resulting bead into a nice fillet. Putting a bead on the other side is a good idea, just to keep water from seeping into the joint.

is what makes Lexel work well for plastic boats, IMO. the seal is able to expand/contract with the hull due to movement and temperature changes. a more rigid sealant might crack or detach from the hull. The fact that it’s also not hard to peel off facilitates refreshing the seal without damaging the minicell foam.

When you apply the new Lexel one thing you can try is push down on the deck a few times to force out any trapped air in the form of bubbles, that way you can smooth over and fill in those spots before the Lexel cures.

Bubbles in Lexel
The reason you had “bubbles” in your Lexel bead (very common) is because you applied or stretched the bead too quickly. Lexel is maddeningly difficult to handle and if you try to apply the bead at the same rate that we’re all accustomed to apply silicone, it will stretch too much and produce bubbles in the bead. You need to be extremely patient and apply the bead slowly, not stretching the bead, otherwise bubbles will form. Go slow, very slow . . .