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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

extended motoring,

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clayC
Navigator

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USA
207 Posts

Initially Posted - 11/07/2013 : 10:10:47

I may be headed over to Catalina for Christmas and with short days I think I had better just get over there so down goes the engine. Anyway, is it better to motor with the keel up or down? It seems more efficient up but maybe a bit rocky?

Clay C

Kamalla 1980 C25 SK/TR

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 11/07/2013 : 10:29:32

If your keel lifting hardware is in good shape (so you aren't afraid the keel might suddenly drop), I would raise the keel so that you get less drag and better tracking. Loss of stability will not be a problem if you're not sailing.

Others will say it is always dangerous to have the keel up because the lifting hardware could always fail.

Edited by - sethp001 on 11/07/2013 10:30:59

Davy J
Master Marine Consultant

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USA
1511 Posts

Response Posted - 11/07/2013 : 10:31:01

Tested this out recently, motoring in calm waters with the keel down, decided to raise the keel to see if it made a difference. Raised the keel, GPS speed over ground stayed the same. So in my unofficial test, it didn't make any difference.

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dasreboot
Admiral

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804 Posts

Response Posted - 11/07/2013 : 11:14:24

i have to keep raised to exit a shallow creek. Never noticed any difference in speed or "rockiness" up or down

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 11/07/2013 : 11:33:54

The reduced drag with the keel up will not improve your max speed while motoring, which is limited by your displacement hull form and size. However, reduced drag will allow you to get your boat to max hull speed with the motor running at lower RPM, using less gas.

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Stu Jackson C34
Admiral

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844 Posts

Response Posted - 11/07/2013 : 12:39:28

Yes, I agree, it is dangerous. There are unexpected wakes you may encounter from broadside. Not a good place to be with your keel up. We sailed out of a seven mile estuary with ferries, tugs and motorboats. Sideways wakes were always dangerous even with our full keel. I wouldn't. You boat, your choice.

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Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 11/07/2013 : 17:47:18

Raising the keel does not significantly reduce drag, because the C25 keel does not retract into a centerboard trunk. Thus, raising the keel does not reduce the wetted surface, which is primarily responsible for the drag that is caused by the keel. Raising the keel does not increase speed or reduce the load on the engine.

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 11/07/2013 : 19:32:31

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 Raising the keel does not significantly reduce drag, because the C25 keel does not retract into a centerboard trunk. Thus, raising the keel does not reduce the wetted surface, which is primarily responsible for the drag that is caused by the keel. Raising the keel does not increase speed or reduce the load on the engine.
<hr height="1" noshade id="quote"></blockquote id="quote">

Part of the keel does in fact "retract" into the hull. More significantly, flow dynamics along the keel in the lowered vs. retracted position are different.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 11/07/2013 : 22:42:54

I'd call it a crapshoot. A little less wetted surface, but the wetted surface that remains is mostly in the turbulent water along the slot and no pretense of a refined entry on the leading edge and the greatest thickness near the trailing edge. I can definitely say that it will be less stable and sluggish to the helm from experimenting in light air a couple of years ago.

Edited by - Dave5041 on 11/07/2013 22:46:08

TCurran
Admiral

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USA
588 Posts

Response Posted - 11/08/2013 : 10:34:14

I generally motored with the keel up, but that's because of the skinny water in my sailing area. If depth was not any issue it would have been down, not for any of the reasons listed above, but out of laziness. Why keep lifting and lowering when there is no need

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Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 11/08/2013 : 11:16:46

The S2 7.9, for example, has a centerboard that raises clear of the water, and raising it reduces wetted surface. Even though raising it makes the S2 faster downwind, PHRF mandates that the S2 7.9 be raced with the board down, for safety.

The C25 swing keel, by comparison, swings up into a very shallow depression, but it is not raised clear of the water. It is still wetted, and the water still flows across it's surface, and, if raising it has any effect at all, it is insignificant.

I helped a racer/friend experiment with his swing keel C25, raising and lowering the keel repeatedly, on different points of sail and also under power, while watching the knotmeter to see whether there was any noticeable speed difference, and we could find nothing at all.

In sheltered waters, like a small inland lake, it's unlikely that the waves will ever be big enough to endanger the boat by having the keel up, but in open waters, the risk is much greater. Even so, I was on a 28' 8000 lb. full keel boat that was rolled so violently by a passing 50' Sea Ray in the Severn River in Annapolis that it's spreaders came within a few inches of the water. I'd hate to see that happen to a C25 with the keel up.

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clayC
Navigator

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USA
207 Posts

Response Posted - 11/08/2013 : 13:38:22

Thanks for the input. down the keel goes. the nights I have spent on the Lake (Utah Lake) its always a calmer night with the Keel down. Even though my keel hardware is very well maintained, the Keel dropping is a scary thought. Thanks again.

Clay C

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