Keel improvements
By Peter Nielsen
Jabberwock, the BoatWorks project O’Day 25, was looking very scruffy around the underparts. The boat had been standing for so long that most of the paint had just fallen off the bottom, and the keel was looking particularly seedy. There was no way we could launch the boat with the keel in such bad condition. It was time for a makeover. A proper keel job done by a boatyard will cost upward of $1,000, but we reckoned we could do it ourselves for a fraction of that. We were lucky in that the keel was lead; a cast-iron keel would have been much more labor-intensive.
If you want to get the last ounce of performance out of your boat, you may be able to buy a set of templates for your keel (try the builder, or www.computerkeels.com). These will ensure that your keel is perfectly symmetrical and fair on both sides. Enthusiastic racers may want to do this, but for the average cruising sailor, near enough is good enough. Even an imperfectly faired keel will improve your boatspeed.
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1. This keel is fairly typical for its age. It’s taken a bit of punishment over the years, and the old fiberglass skin has lifted off in patches. Fairing it will not only improve the water flow over it and reduce drag, it will also provide a better substrate for paint. Photo by Peter Nielsen |
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2. Gentlemen, choose your weapons. The implement of choice is a beefy random orbital sander—in our case a Porter-Cable—with a variety of sanding disks. It pays to buy disks in bulk, because you’ll use a lot. Photo by Peter Nielsen |
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3. Make sure you have everything you need on hand before you start. Once you’ve started a project like this, you won’t want to put down tools to go buy a brush. Stock up on resin containers, disposable brushes, gloves, scrapers, and acetone. Photo by Peter Nielsen |
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4. We’ll need to seal the joint between the hull and the keel. Some work has already been done here. Over the years, impurities at the top of the lead/antimony keel casting had become brittle. They had been chipped out, and the gaps were filled with a paste of thickened epoxy resin. Photo by Peter Nielsen |
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5. We start off using 36-grit paper along the hull/keel joint. We’ll be covering the joint with fiberglass, and the heavy grit leaves a nice rough surface for the resin and glass to bond to. The dust that results from sanding old antifouling paint, fiberglass, and lead is not pleasant, so if you do a job like this make sure you cover up as much skin as possible and use a high-quality respirator. Photo by Peter Nielsen |
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6. There’s no need to go down to bare metal, but we make sure the old loose fiberglass is ground off; in many places the bond between it and the lead is still strong, so we don’t need to take it all off. Next, we wipe the entire keel with acetone to make sure the epoxy has a nice clean surface to bond to. Photo by Peter Nielsen |
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7. Now we need to skin over the hull/keel joint. This will strengthen and seal the joint. We first cut out four pieces of 17-ounce biaxial mat, two for each side of the keel. This is equivalent to four layers of glass cloth. The second layer will be slightly wider than the first. We wet out each layer of mat very thoroughly with a 5:1 mix of WEST System epoxy and 105 fast hardener. Photo by Peter Nielsen |
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8a and 8b. One at a time, we line up the strips of mat along the hull/keel joint—it may be easier to have a helper for this—before using a rubber roller to smooth down the mat and work the resin into the weave. We repeat this on the other side of the keel. Photo by Peter Nielsen |
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8b Photo by Peter Nielsen |
