Rubber to fibreglass/gelcoat glue

[GILow]

Hello Cruisers,

A while back I posted an idea of using docking rubber as a rubbing strip on our boat. As a result of that discussion, I have gone ahead and purchased two 11m lengths of rubber, one for each side of the boat, and I plan to attach them very soon.

I originally considered ways of attaching them mechanically, using a length of stainless steel strap inside the hollow extrusion, and tapping threaded holes into that strap, but I have been forced to abandon that idea for two reasons. One, I had a "boy look" at the existing stainless straps on the rub rails and failed to notice they were in sections (ok, so I could weld them...) but more importantly, I realised the logistics of handling such an awkard combination of flexible rubber extrusion, heavy stainless strap and trying to get the whole lot straight was just too much.

So now I am favouring glue and using (large/course) self tapping screws into the back face of the rubber extrusion. (There are already holes in the side of the boat, spaced about 9 inches apart, holding the current timber rub rail, so the screws will not require any drilling of the hull)

I phoned the local 3M office, and was recommended a product, DP110 flexible epoxy, but after reading a lot about it I feel it may be a bit TOO strong, and very difficult to handle, given it will be tricky to get the rubbing strips in place and straight within the half hour pot life of the compound. Unfortunately the only person available at 3M was a nice lady who, by her own admission, was not really comfortable making a recommendation and was working from a computer system that was not assisting her greatly.

So further searching revealed 3M Marine 5200, which was much slower drying, but does not specifically mention natural rubber as a compatible surface. I have found threads on various forums from people who claim to have used it for bonding rubber to gelcoat, but I would feel more comfortable hearing of a success story from a CF member, or, a recommendation of a product that you think will do the job.

The requirements are that it bond natural rubber to gelcoat, with all the sensible stuff like ensuring the surfaces are free of grease, oil, silicone wax etc, and I am happy to mechanically key both surfaces to get a good bond if required.

Any suggestions?

Matt

[BMWshoe]

http://www.hambys.com/light-duty.html

You might contact Hanby- they specialize in attaching rubber keel guards on bass boats. They hold up to beaching and 80 mph speeds. They use a 3-M adhesive.

[GILow]

Thanks BMWShoe. Sorry, I missed your post somehow. Went with Sika 291 and 215 primer in the end. Sticks brilliantly on the test piece, now I just have to hope it works as well on the boat.

[GILow]

Follow up to those searching on these ideas, the sika 291 and 215 primer appear to have worked well. The rub rail recently jammed on the boarding steps as I was coming into the pen, creating a pretty impressive shearing force on the rail, but the sika held nicely.

Matt