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 Swing keel
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Oneday
Deckhand

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USA
20 Posts

Initially Posted - 05/29/2022 :  00:04:52  Show Profile  Reply with Quote
Hey everyone. I just purchased a Catalina 25 swing keel version. I will be keeping it on a mooring in salt water. There are no worries about shallow water where I am. Is it ok to just leave the keel down for the season? Or should I raise it after every sail? And do people raise the keel when sailing downwind? Thanks Dan

Steve Milby
Past Commodore

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USA
5723 Posts

Response Posted - 05/29/2022 :  08:43:11  Show Profile  Reply with Quote
Here's what the C25 owner's manual says about the keel maintenance.

"ELECTROLYSIS PROTECTION

If you decide to keep your retractable-keel model in the water, especially salt water. Bottom paint is a must, plus periodic cleaning and removal of marine growth from the keel trunk slot. The possibility of corrosion to the keel and keel fittings is greatly increased. Keeping a retractable-keel model in salt water for lengthy periods is not recommended.

Should you decide to keep a retractable-keel model in the water at a slip or mooring for extended periods where electrolysis is a potential problem, the following suggestions may help to protect the keel assembly. The keel pivot pin is made of siliconbronze, the hinge castings are of brass, and the keel itself is made of iron. To retard electrolytic action which will "eat" away the metals, drill and tap the side of the keel (near the forward edge) as close to the keel Pivot assembly as possible. Then attach a teardrop shaped "zinc." Keeping the keel in the raised position will help prolong the life of the cable (7x19, 1/4" S.S.) by keeping as much of it out of the water as possible."

There's a menu on the upper left corner of this page. Look down it to "Manuals and Brochures." Click on it and you can print out a complete owner's manual for your boat.

Years ago I sailed with a friend on his SK C25, and we experimented with raising and lowering the keel downwind. His knotmeter showed no speed difference with it up or down. There are two factors that could theoretically change when you raise the keel. In order to justify raising the keel, you'd have to either significantly reduce drag caused by dragging the leading edge of the keel through the water, or you'd have to significantly reduce the amount of wetted surface. (A boat's wetted surface is the area that is immersed in water, including the hull, keel and rudder surfaces. Reducing wetted surface reduces drag.)

Because we saw no difference in speed when we experimented with it, I think the answer is that neither of those two factors significantly reduces drag.

The first factor: The leading edge of the keel is shaped to be reasonably efficient hydrodynamically, but when the keel is raised, the top of the keel becomes the leading edge, and it is flat, and that flat surface creates significant turbulence, and consequently significant drag. Thus, any gain related to the first factor is cancelled out by the turbulence created.

The second factor: On some retractable keel boats, the keel or centerboard either rotates up into a centerboard trunk, or is lifted clear out of the water. Neither of those things happens with a C25 SK. The C25 keel just rotates up against the boat's bottom. It is still fully immersed in water. Retracting it doesn't reduce the area of wetted surface.

At first it seems logical that raising the keel downwind would have a beneficial effect, but when you think about what's really happening hydrodynamically, why spend your time and energy doing something that isn't helping, when you could be doing things that really do matter, such as setting a whisker pole to hold out the jib when sailing downwind?

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore
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Stinkpotter
Master Marine Consultant

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Djibouti
8873 Posts

Response Posted - 05/29/2022 :  14:27:00  Show Profile  Reply with Quote
On the question about the mooring, while Catalina suggests leaving it down will increase corrosion, what Steve says about how it raises (still fully immersed and mostly exposed), I would suggest otherwise. The reason is that if the lifting system fails (breakage of the cable or an attachment), the 1,500 lb. keel can fall with enough force to crack the forward area of the trunk, sinking the boat. It could be caused by some pitching in a boat wake or whatever... This is not my imagination--I (we) know somebody to whom it happened twice, fully sinking in his slip. Maintenance is one part of the prevention, and critical with the swing keel. But why not just leave it down? I would, but I had a fixed fin keel so never faced the decision. Somebody else might recommend that the stresses on the pivot assembly are greater when the boat rocks with the keel down... We'll see.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, ex-OUPV,
Now on Eastern 27 $+!nkp*+ Sarge (but still sailing when I can).

Edited by - Stinkpotter on 05/29/2022 14:29:53
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Steve Milby
Past Commodore

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USA
5723 Posts

Response Posted - 05/29/2022 :  15:43:17  Show Profile  Reply with Quote
I agree with Dave. The SK should be kept down as much as possible to ensure against a sudden drop and also because there's no benefit to raising it downwind. The owner's manual was written when C25s were just starting production. I suspect the designer thought the structure was strong enough that it could withstand a sudden drop of the keel without severe damage. The manual did recommend against keeping the SK in salt water for lengthy periods.

The experience of owners since then has shown that keeping the keel down and regularly replacing the cable and associated hardware are the best ways to prevent a sudden drop of the swing keel. Attaching a sacrificial anode to the keel also helps. Some of our members have recommended replacing the mechanism every couple years, and I don't recall hearing of a sudden drop where the owner has followed that regimen.

I should have added that in my previous post, but I didn't for 3 reasons: (1) We can't always think of everything, (2) that post was already long, and (3) I wanted to leave something for Dave to contribute.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Edited by - Steve Milby on 05/29/2022 15:48:56
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Stinkpotter
Master Marine Consultant

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Djibouti
8873 Posts

Response Posted - 05/29/2022 :  19:49:59  Show Profile  Reply with Quote
Gee, thanks Steve!

Standing by...
db

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, ex-OUPV,
Now on Eastern 27 $+!nkp*+ Sarge (but still sailing when I can).
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cflowers
Deckhand

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USA
2 Posts

Response Posted - 06/01/2022 :  07:07:44  Show Profile  Reply with Quote
I have a swing keel and I keep it up while in the slip. I have to because of the underwater cable bracing for the slip. I changed the keel cable last year and will do that again next year.

I do not lose sleep worrying about a sudden keel drop. I donít think the keel cable is any more likely to break than your standing rigging. I think the more likely culprit for a sudden keel drop would be the winch slipping. My winch was rebuilt a few years ago because it was slipping during operation.

-cf

-cf

Craig Flowers
Champaign, Illinois
SV April Fool
C-25 SK #824
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Derek Crawford
Master Marine Consultant

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USA
3300 Posts

Response Posted - 06/01/2022 :  15:44:25  Show Profile  Reply with Quote
Steve, what was interesting when we owned our original C22, running downwind if we raised the keel about 1/3rd of the way, we gained 1/2 knot. (We did not do it while racing - just when out experimenting)

Derek Crawford
Chief Measurer C25-250 2008
Previous owner of "This Side UP"
1981 C-25 TR/FK #2262 Used to have an '89 C22 #9483, "Downsized"
San Antonio, Texas
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Steve Milby
Past Commodore

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USA
5723 Posts

Response Posted - 06/01/2022 :  16:34:44  Show Profile  Reply with Quote
IIRC, about 1/2 of the C22 keel swung up inside the hull. That reduced the boat's wetted surface. The same is not true of the C25.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore
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Derek Crawford
Master Marine Consultant

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USA
3300 Posts

Response Posted - 06/02/2022 :  07:58:19  Show Profile  Reply with Quote
That makes sense now.

Derek Crawford
Chief Measurer C25-250 2008
Previous owner of "This Side UP"
1981 C-25 TR/FK #2262 Used to have an '89 C22 #9483, "Downsized"
San Antonio, Texas
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ddougla
Deckhand

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USA
3 Posts

Response Posted - 06/21/2022 :  18:32:41  Show Profile  Reply with Quote
The old handbook I have for my Catalina 25 says to always moor the boat with the keel down. It says three problems result when the keel is up: 1) The keel moves independently of the boat. As the boat rolls at its mooring, the keel wears the pin and the hole in the keel itself. 2)The extra motion may cause the cable to fail earlier. 3) The reduced righting moment will cause the boat to roll more in its slip. The potential for tangling rigs with your neighbor's mast is greater.
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dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 07/09/2022 :  14:30:18  Show Profile  Reply with Quote
I have a 1975 C22, Steve, and used to own a swinger C-25. Only about 2-3 inches of the aft edge of the keel comes up into the boat, nowhere close to 1/2 of the keel. With the C22 keel fully retracted as it is on the trailer, there is still easily 10 inches of keel exposed below the hull. Unless the water gets too shallow under your boat in the slip, keep the swing keel down. Even if you have to raise it some to get in and out of your slip, like we had to do at one marina, leave it down. Avoids possible keel trunk damage/sinking from a free-fall and takes pressure off of the winch which should prolong the life of the winch brake hardware.

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN
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Boomeroo
Navigator

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Australia
128 Posts

Response Posted - 07/16/2022 :  10:33:46  Show Profile  Reply with Quote
Hi my S/K is now 40 yo and has been on a salt water swing mooring its whole life . It sank twice with previous owners who left it with keel up .. I have a Zink anode and that disapears in about 18 months . I raise the keel to get to my jetty in 3 steps ie up 1/3 ,head in raise it again etc if a cable were to snap the keel would hit mud and not destroy the keel case as previous. Examin the cable each year . I replace it about 3 yearly . Problem is growth on cable or anti foul cable . Copper anti foul works but seemed to effect the cable . I now leave it unpainted but lift it regularly ,monthly, to stop growth build up . Inspect roller with cheap cable camera when out of water for anti fouling..

Graeme Bishop boomeroo Australia
C25 SK
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