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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Faired keel

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Initially Posted - 02/02/2008 : 21:15:44

Just finished my first sail after fairing my s/k and new pivot pin - WOW. Light air 10 - 12. points so much higher while maintaining speed. My Raymarine ST40 needs to be calibrated for wind direction - relative and true wind direction not even close to telltales - so I don't know the angles, but subjectively it really improved. We could easily hold 3+ knots to windward. I am sure this is the first attention the keel has ever had, while Pearl has many CD upgrades, she still had the old eyebolt cable attachment.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

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Chris Z
Captain

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452 Posts

Response Posted - 02/02/2008 : 22:07:58

Dave,
Considering doing just this to my SK after this year. I would like to see some pictures and details of the whole project. I wondered if you pulled the keel out completely from under the boat?

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Steve Milby
Past Commodore

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USA
5908 Posts

Response Posted - 02/03/2008 : 07:20:52

It also helps the old cast iron fin keel boats. A boat with bumps and depressions on the keel can't point as high or foot as fast as one with a smooth keel.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 02/03/2008 : 10:00:51

No photos. I had it done by he yard in the winter so Pearl would be ready to go to Pensacola in January. I have no way to lift the boat at home. I did the job on my old Clipper 21, but that was an 1800 lb. boat with a 600 lb. keel. That wasn't to big of a deal; it took about a week. If you can get the boat high enough, it could be done without removing the keel.

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stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 02/04/2008 : 11:35:42

Pictures.
Must have pictures.
And details of materials used etc.

sand blasted? soda blasted? sanded? Holes filled?

Two springs ago I scraped most of the paint off my SK and filled the pits and and holes with marine-tex then put two coats of hard bottom paint on it. It's smooth and looks pretty good after two years....even though it was not the ideal way to tackle that job.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 02/04/2008 : 19:08:59

If I had done it myself, I would have pictures. It was removed and sand blasted, filled with epoxy and non colloidal filler, and ground smooth. It was Finished with a bonding primer, three barrier coats, and two ablative bottom coats. It looked great, but a sandbar at the launch ramp in Gulf Breeze and a very narrow and irregular channel into Little Sabine Bay may have left it a little less pristine. I'll see when I pull her out at the end of the month.

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Renzo
Admiral

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USA
621 Posts

Response Posted - 02/05/2008 : 08:05:27

I did this myself many years ago and while it helps with speed and pointing I wish I knew then what I know now. Namely, that true faring of a keel requires the use of keel faring templets purchaced from the manufacturer or other source. Without the templets you are smoothing the surface of the keel, but with the templets you not only smooth but reshape the keel to the optmum shape as envisioned by the designer. The keel, even on a new C-25, rarely comes from the manufacturer with a perfect shape. It may be smooth but there are deviations, High spots and depretions that may run the length of the keel. A keel that is the optimum shape will give optimum performance (only important when racing)but if you are working on the keel anyway why not go for broke.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 02/13/2008 : 18:06:29

Here are a couple links to old posts with some info on keel fairing. If you search the archives, there are likely other posts on the general topic out there. Might be worth your while to poke around.

[url="http://www.catalina-capri-25s.org/forum/topic.asp?ARCHIVE=true&TOPIC_ID=6230"]Swing Keel Job - All or Nothing?[/url]

[url="http://www.catalina-capri-25s.org/forum/topic.asp?ARCHIVE=true&TOPIC_ID=2382"]Swing Keel Epoxy Barrier[/url]

As for fairing templates, you can probably make your own using a free NACA foil plotting program. Print the foil cross sections, trace them onto plywood, and cut out your fairing guides. Keep in mind, the NACA foil fairing cross sections should be parallel to the water flow, not perpendicular to the leading edge.

-- Leon S.

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.