Keel fairing, templates etc |
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Bill Layton
Commodore Joined: 15 September 2002 Location: Canada Status: Offline Points: 551 |
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Posted: 06 September 2009 at 5:01pm |
This is a copy of an email I rec'd from Frank Fletcher. Some interesting info. Thanks for sharing this Frank.
"I have now got Voila on a trailer at home and have begun working on her trying to maximize her hull speed potential. I just completed removing 25 years of bottom paints, sanding primer/sealer, etc. What a job! I hope this is the last time I ever do this kind of work. Of interest was the keel. I purchased the offsets and drawings from Farr and made up the templates in a style I have used before and began the process. I was suspicious of the keel's shape as I knew it had received substantial work about 10 years ago in Vancouver where the yard did not use fairing templates, and using some large make-shift dividers found that measuring points were not in sync with the offsets. In my method of doing this I start with a "full" template at the top station, which in this case I used the top of the lead. Naturally the template would not make it up to that point, leading me to start grinding. I finally got it to fit just about perfectly where it belonged. In doing this, I discovered that the keel is a wonderfully cast piece of lead, with very minimal deformation. There was possibly a small expanded area at about the 50% rear of leading edge area in the top third of the keel, but once that lead was trimmed, the template fit snugly into it's measuring point with no more that about .5mm gap, and that is about as accurate as I was able to make the template from 3/8 ply. The template/plate I made to fit up against the bottom of the keel was also a nice match once all the fairing putty, bondo, etc, that had likely been added by several different people, owners, and yards, had been removed. I then worked with a stiff straight edge working between the 15 per side measuring stations and there was almost no daylight against the straight edge once "all" filler was removed. This means that the lead is very accurately cast to it's design and so for the most part, fairing this keel to specification has meant filler removal. I have had to fair out the toe of the keel which no doubt has hit numerous rocks in 25 years, resulting in yard's grinding away the smashed bits and smoothing them out with bits of filler, etc, and the same with the very bottom tail on the trailing edge which I suspect had been damaged and trimmed because it had about a 2" radius on it instead of being square. But mostly, anything others did to this keel during the boat's life has only detracted from the original keel design. For any members talking about truing their keel, I thought my own experience might be interesting and was going to post it but could not log on. As the boat it going to be dry sailed for a while, I have decided not to put anything on the bottom and am going through the long root of sanding and bringing up the original bottom gel coat after using #80 grit. We used stripper to remove 95% of the VC17 and others, and then used 80 grit alternating between flat sanding with a 6" random orbital and a 16" straight in-line sander. After the 80, which got me down to the gel coat, I have manually long boarding starting with 120, 220, 320, 400, and then machine polishing. Hoping to be able to skip the 320, but will see when I get there. Obviously I will have to prime and re coat the keel and rudder. No doubt spraying after the 80 grit with some performance bottom paint would have required much less effort, but I'm into it now. My shoulders, back and neck are screaming and I won't need to go to the gym for a while" Edited by Bill Layton - 07 September 2009 at 3:32pm |
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