Hull / Keel joint - Sikaflex 291 or 292 or ?

[joe17]

Hi,

Which is the right Sikaflex to apply for a hull / keel joint. 291 seems to be mentiond, but then also 292. Is it either of them?

Any other products recommended?

Cheers
Joe.

 

[SvenglishTommy]

Well 292 is the stronger, which for those kind of permanent joints is probably best.

I would use 3M 5200 which is stronger still, and more importantly has a higher elasticity.

*disclaimer.

I work for 3M, but have nothing commercially to gain from recommending their products on a UK boat forum

 

[VicS]

Cannot make any comment about 3M products

Sikaflex 291 is a general purpose adhesive sealant
Sikaflex 292 is a flexible adhesive for structural bonding

The users guide leaflet and the Marine Handbook are both on http://www.bluemoment.com/downloads.html

Note also the correct primers for the substrates for best performance

 

[SvenglishTommy]

You dont even need to prime the surfaces, the bonding strength of these adhesives is immense, about 25kg per cm2 on fiberglass and almost 40kg per cm2 on iron. The thing is we're not using them as structural adhesives, we're using them as sealants. Personally I think most of this stuff is too strong for the purpose, kinda nice to know that your keel would probably stay in place even if all your bolts rusted away though

 

[savageseadog]

One area to consider is the set or cure time because you don't want the sealer going off before you've had a chance to marry the keel to the hull

 

[joe17]

Thanks. Seems 291 is probably enough. This is just an ugly patch on a small leak. Job needs fixing properly one day, just not now.

I have no idea of the technical strength of Sika, but it does seem to be immense. A few years back someone dropped a tube on the road and it got run over. Whoever dropped it left it. It got flatter, but then set and remained there. Still a significant bit of it there now.

And thanks on the 3M stuff. I'll look out for it. Quite sure they'll have sika, hence the original question. If there are options then I can make a choice.