how strong is 3m 5200?

[BurnabyRocket61]

Does anyone know if the 5200 is less flexible than sikaflex 292? Or is there anything else that might be even more firm with as good a bond? I'm planning to bond the edge of the raised epoxy/ply deck to the primed alumimun hull. and since I plan on painting over this joint with Perfection, the less movement there is, the less the chance of the paint cracking?

[mydauphin]

How about just use epoxy fairing compound?

[BurnabyRocket61]

Good idea, I had thought about that, but I wasn't sure of its bonding strength, and with the difference in air temp to water temp in some of the lakes up here I'm sure there will be some fairly rapid expansion and/or contraction when it's put in and hauled out, and the last thing I need is for that joint to separate. A crack in the paint is one thing but water egress to the holds below is another. As you can see i've already used 292 on the ends of the livewell/ beer cooler, but I'm not to worried about the paint there since its below deck.

[PAR]

3M 5200 is more rigid the 292 and has a stronger bond.

You want to "marry" your modifications to your hull, but retain enough flexibility to account for the dissimilar material expansion rates. I'd recommend West System GFlex epoxy for this job, with properly prepped Aluminum. It will be flexible enough and still very rigid.

[Frosty]

292 will break down with oily bilge water.

[BurnabyRocket61]

Well I used a product from Industrial Formulators called Gel Magic. It's a 2 to 1 gel epoxy that within a few minutes of being mixed turns to the consistency of vaseline. It' designed to bond two dissimilar substrates that have a gap, it's easy to work with, fillets nicely, cures to touch in about two hours, and the best thing is that it does not sag, so no more guessing how much silica you need to mix to get the right consistency. So thanks, and I'll let you know if and when it fails, and the paint cracks, at which point I figure I'll run a bead of UV poly along the crack and call it a day.