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I have a 1967 Islander 21 that I am refinishing. Below are some photos of the joint where the keel meets the hull. A previous owner had covered this joint with some sturdy silicone, but it is failing to stick and I figure I should remove it all.
Question is, do I need to re-seal this joint? A boat buddy of mine says it's unnecessary. I plan to keep her in the water (Port Townsend, WA) from April to October, then clean the bottom and store her in my yard each winter.
You can see the flap of silicone against the roller at the far right:
That silicone isn't doing anything to strengthen or waterproof the keel joint--it's just something someone gobbed on there in an attempt to fill the usual cosmetic crack that occurs at these seams with predictable regularity. The keel is bolted to the hull, and the mating area is typically well and thoroughly bedded at the time of installation. Because keel castings are often rough and not necessarily perfect fits, the exterior of the seam is often covered with fairing material, which cracks over time with the natural movement of the boat--particularly if the material is thick, which it frequently is.
First question: does the keel leak in any way when the boat is in the water? (Conversely, does water inside the boat leak out when the boat is stored out of the water?)
If the answer to both the above is "no", then the integrity of the real seal between keel and hull is sound.
Either way, remove the silicone. If you have signs of other problems, or your answer to the questions above was "yes", grind away the bottom paint and any other loose material, and post an update at that point if you need to. Otherwise, once the seam is brought back to sound material, either refill and fair (if needed to match existing) or apply an external bead of an adhesive sealant, which will cover the crack and also flex with the boat's movement and (in theory) help inhibit further cracking.
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Tim wrote:First question: does the keel leak in any way when the boat is in the water? (Conversely, does water inside the boat leak out when the boat is stored out of the water?)
Absolutely not. The only water that ends up in the bilge is rain water (other issues). Several of us have tasted it to be sure.
I've just discovered your project blogs Tim. What a jackpot of knowledge and experience. I look forward to reading them all. Thanks for your effort.
Don't you have a charred hull to tend to?
Thanks for your suggestions here. I'll post updates in the Projects forum.