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Old 20-03-2010, 16:59   #1
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Best Way to Seal Hull / Keel Joint ?

I am getting my boat ready for the water and I want to seal the keel/hull joint on my 1978 Pearson 26. The seam is pretty tight (compared to a lot of other boats in the yard, for example) and there isn't much movement on the keel. Still, there is a small space around the entire keel (which is cast iron) and of course there are some rust streaks where the water got in and out.

I am planning on sealing this seam with 3M 5200 Marine Sealant, which I'm told is strong and flexible enough to keep the seam closed up for at least a few years. My question is: is there anything I should do before I apply the sealant? I did some light grinding and used a wire brush to clean it up but I'm wondering if I should do more. I have some POR-15 Rust locking paint that I am going to be using on the top of the keel bolts. Is it wise or worthwhile to squeeze some of that in the keel/hull seam as well to stop any further corrosion on the bolts for example? Should I do anything special to dry the seam before I seal it? Perhaps acetone or a heat lamp?

Any advice you can give me on this rather simple yet important maintenance would be greatly appreciated.

Thanks,
Jack
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Old 20-03-2010, 20:56   #2
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AND check the bolts.

b.
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Old 21-03-2010, 07:20   #3
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If the joint is the same width it has been always, I would go ahead and use black 5200 slow cure (takes 7 days to cure) after prepping the joint with Ospho. Ospho will stabilize the rust and is a primer which doesn't leave a coat that can flake off like a paint.

I would use a heatgun to dry & blow out the joint before starting with the Ospho. I would use the heatgun again before applying the 5200. Don't make it hot, just until the joint feel warmer than your hands. After you apply the 5200, the air in the cavity will cool down drawing the 5200 in. While this is good, it might look like it's crimping a lot and require a second application for the finishing touch, so check a day or so after the first application.

If the joint has a wider seam than it used to be, the only sensible thing to do is lowering the keel. This would be caused by rust expanding. I've seen yards doing that job in Trinidad and it's much quicker than you think when you have access to the keel bolts.

cheers,
Nick.
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Old 22-03-2010, 10:43   #4
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The joint on my boat had a crack around it in from the old caulk from going onto a sand bar . In the end I wire wheeler the line, taped off, and applied some Life Caulk that I smoothed out with a putty knife. In the end it looked like a 1" strip of black electrical tape (people in the yard were asking what the electrical tape around the keel was for). Two weeks later ther caul was set well and I couldn't pull it off etc.

For me Iliked the idea of not using something less "permanet" than 5200 or expoy. We'll se next year.

PS - I had so sign of any joint leakage and may have done a different "fix" had there been.
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Old 23-03-2010, 12:06   #5
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I had the same problem with a lead keel-to-fiberglass stub joint. I cleaned the 1-2mm wide crack out with a hacksaw blade (being careful not to make it any larger), made sure it was dry (by waiting a week) and "spackled" it with 5200. This approach seemed to force 5200 into the crack and, hopefully, waterproofed it too. It has held up nicely for about 4 years, so far.
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Old 24-03-2010, 05:41   #6
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We have a p26 with rusty keel bolts. Does anyone have experience replacing one bolt at a time so as not to have to remove the keel? It's in the yard now and was hoping to maybe cut the top of each bolt off, drive it through from above and replace bolt, washer, nut one at a time. There is some rust weeping from the hull/keel joint. I'll gouge out old fiberglass and fill with 5200.
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Old 24-03-2010, 07:03   #7
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Many years ago I replaced rusty keel bolts on a Columbia 26. The "bolts" were threaded rod screwed into the iron keel with a nut and washer in the bilge i.e. no bolt heads and no outside access. We double-nutted the rod/bolts, backed each out one at a time(after much banging and straining on breaker bars) and replaced each with new steel threaded rod and a new nut and washer. (Glad I had my Dad helping me on that one!)

I don't understand your bolt configuration (I assume that the bottom ends of the bolts are exposed) but we had no problems replacing 1 or 2 bolts at a time while on the hard.

You might consider getting all the bolts ready to remove (loosened up), safely chock up the keel, have the yard pick up the boat separating keel from boat and then clean and re-caulk the exposed keel shoe and hull mating surfaces with 5200 or polysulfide. More work and expense for sure, but probably a better result.

Good luck.
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Old 24-03-2010, 09:28   #8
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I think a lot depends on the material used for casting the keel. If it's lead, you can easily replace one by one if there is external access to bolt heads. If the keel is steel or iron, I would follow wallandj's suggestion and chock & separate. With a 1 foot separation, the boat can be chocked again when the stands are in good positions (bulkheads & centerline fore and aft of keel). This gives you all the time for cleaning up and preparing for creating a tight fitting mating surface. I've seen that done once and they used epoxy + colloidal silica on top the keel.... wait for gelling stage, dropped light plastic wrap over it and used the travelift to lower the hull just enough to touch the epoxy everywhere, stamping the shape of the hull into it, lift and chock the boat again, wait for full cure, cleanup and re-bed and fasten it again. Afterwards, there was no visible crack anymore. They finished the job in 3 days and this was Peake's yard in Trinidad.

cheers,
Nick.
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