sealing w sikaflex 291

[Paul Silverman]

I just finished sealing my old boat (cedar on oak) with sikaflex 291 below the waterline (dug out the old hard sealant). She is caulked with cotton in places but plank edges were originally glued (in 1941). The boat has been out of the water since last summer and is dry. I decided to pre-swell her a bit by filling w water to the second plank above the garboard- the the top of the floors). Very little water leaked out and now I'm worried since the planks still need to swell. The sikaflex was applied when the hull was very dry (not as recommended when planking has shrunk only 50%).

Has anybody used sikaflex on a dry hull? Is it flexible enough to compress or to squeeze out between the planks before there is enough pressure for them to split or to pull away from the frames?

[Bob Cleek]

The sikaflex should be fine. It's plenty flexible. The real problem with the stuff is getting it to stick reliably on previously finished wood. If it leaks, put more on or do the job over again. Every wooden boat leaks a bit anyway. Enjoy the boat and quit obsessing! LOL

[Paul Silverman]

Bob, as always thanks for your advice. I painted with primer in the seams before inserting the Sikaflex and it seems to be sticking for now. The boat is "Kelpie"- a 1941 gaff cutter designed by Bill Garden. If you are familiar with Brain M's "Spray" in Millbrae, Kelpie is a similar, but smaller, design.

-Paul

[pcford]

Paul Silverman posted 07-02-2005
I just finished sealing my old boat (cedar on oak) with sikaflex 291 below the waterline (dug out the old hard sealant). She is caulked with cotton in places but plank edges were originally glued (in 1941). The boat has been out of the water since last summer and is dry. I decided to pre-swell her a bit by filling w water to the second plank above the garboard- the the top of the floors). Very little water leaked out and now I'm worried since the planks still need to swell. The sikaflex was applied when the hull was very dry (not as recommended when planking has shrunk only 50%).

Has anybody used sikaflex on a dry hull? Is it flexible enough to compress or to squeeze out between the planks before there is enough pressure for them to split or to pull away from the frames?


Let's put it this way. A boat which I did recently had been caulked by a previous restorer with Sikaflex on the topsides. Because the boat had been on the hard for a few years and had opened fairly dramatically, I reefed out the seams and replaced with polysulphide. At no small amount of effort.

Polyurethane does not compress well. Polysulphide is preferred in an application yours.

It is possible to warp planks or even to pop fasterners in a situation like yours.

I believe I recall the Kelpie from her time in the Seattle area.

Regards,
pcf