Sideslip with swing keel up - SailNet Community
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post #1 of 11 Old 08-27-2009 Thread Starter
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Sideslip with swing keel up

Our mooring has horrible weed growth in the summer. I have had trouble with fouling of the keel raising cable on my Catalina 22 with weeds. Lately, I have just raised the keel and motored in. I would rather leave and return under sail. My question is, will there be a lot more sideslip with the keel up? On the C-22 when the keel us up almost all of it is still exposed to the water. It is just horizontal rather than vertical.
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post #2 of 11 Old 08-28-2009
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Good question! Since there has been no response so far, I'll give it a shot.

I had a C22 many years ago, and vaguely recall that a little of the keel surface was brought up into a partial centerboard trunk, so that a little of the lateral surface was lost when retracted. Moreover, when the keel is retracted, the foil along the leading edge of the keel is lost. As a result, when the keel is retracted, you lose a little surface area, and a lot of the foil effect.

I sailed the boat a few times with the board up, just to see how it would behave, and it behaved about as one would expect - it sideslipped more to leeward and consequently wouldn't sail as close to the wind.

Whether you can sail on and off a mooring with the keel up depends on your skill and the amount of room you have to maneuver. If you have adequate maneuvering room, I don't see any reason why you shouldn't be able to sail on and off the mooring in ordinary conditions, but it will be more challenging than normal.

My suggestion, however, is that you use the motor to get on and off the mooring. It sounds to me as if you are likely to occasionally snag some weeds with your keel or rudder despite your best efforts, and if that happens, your boat will become nearly impossible to maneuver, and it's no fun to be on such a boat in a crowded mooring field. It's commendable that you want to learn to sail on and off your mooring, but it's difficult enough to do so without the added problem with the weeds. Others might see it differently....
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post #3 of 11 Old 08-28-2009
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I have no experience with swing keel boats, but SailorMon seems to have given some good advice. Here's another thought, trying to sail with the keel up while out in the open water will also give you a feel for how the boat will react, without putting anything in danger. You could tie a fender to your anchor line and deploy it as a target float in a shallow but open area, and practice sailing up to it with the keel up just to give you some experience trying to hit a target with whatever side slip and reduced pointing you may encounter.

Or if the mooring field is not crowded, or you can find a public park mooring or such that has lots of room, go ahead and give it a try on a calmish day, but keep the motor running just in case! The first several times I sailed on or off a mooring I just kept the engine running, although I only needed it a few times. Now I am more comfortable with it and usually do not keep the engine on, but occasionally still will if I am not completely comfortable with the situation.

I do not keep the boat on a mooring however, and most public park moorings I sail on or off of tend to have plenty of room around them to goof up in. I think the real question is how much damage will you cause if things go awry? If the answer is none (except to your pride) give it a try and see what happens! If the damage potential is high, practice elsewhere first.

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post #4 of 11 Old 09-02-2009 Thread Starter
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Thanks for the responses. I hadn't thought about the fact that most of the lift from the keel is generated by the leading edge. With the keel up, there is almost no leading edge! Looking at the line drawing, it does look like I loose a fair amound of keel area when it is up. In the spring (when the weeds haven't started to grow) I sail on and off the pin. However, the mooring field is tight. Is it normal to have mooring pins set such that the swing of the boats cross each other? (no current, wind would have to be zero, or changing 180 for boats to touch)
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post #5 of 11 Old 09-03-2009
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Barquito, I have sailed my C22 into and out of a slip with the keel up and have found that the sideslip is minimal in light air. In heavier air (>15 knots), it can be a problem if the wind is abeam or forward. I have not tried it on a mooring.

The first time I tried it, I was pleasantly surprised to find that even with the keel up, there was some 'bite' of the keel in the water. It was nothing like the sideslip you get in a dinghy with the board up.

As suggested above, recommend you practice on a makeshift mooring in a clear space. Let us know how it works out.

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post #6 of 11 Old 09-23-2009 Thread Starter
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So, I did go out and experiment with keel up and down. I anchored a fender a ways out and sailed off and back with the keel up and down. In the light winds that day I could see there was more sideslip with the keel up. I could, however, still make headway. I guess it remains an option.

As an aside: Previously I had had trouble controlling which way my bow fell off as I sailed off the pin. I kept thinking I would get reverse steerage before it falls off... that never happens! Now I just make sure the boat is swinging in the direction I want it to go, then start easing the anchor/mooring rode out and confirm that the boat is continuing to swing in that direction before I release the line. With the tiller hard-over, I can almost get beam-to before I release the line. (one of those 'well duh' moments)
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post #7 of 11 Old 09-23-2009
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Barquito, thanks for reporting back on your experiment. I guess it just comes down to trying it out and seeing how your boat reacts. Sometimes when I am sailing off the anchor, coming into a slip, etc. I leave the keel down part way, to get a little more bite and still avoid the weeds. It can work if the weeds are deep enough. All depends on wind and how much space you have. Glad to see it worked out for you without a damage report.

Pat

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post #8 of 11 Old 09-23-2009
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For everyone with a swing keel, Try adjusting the keel for balancing. When first raising the keel it is not moving up so much as moving to the aft. Moving the keel just 6" aft substantially changes the center of resistance. This would help boats that head up constantly while under mainsail alone. Some boats may not be built for this but I would think any well designed swing keel would handle it just fine. I would not adjust the keel on a reach or at least anytime I felt abnormal resistance, the sideways force binds the keel and with the power of your winch you could damage and sink your ship. TJ
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post #9 of 11 Old 09-23-2009 Thread Starter
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When singlehanding I usually step into the cabin and crank the keel down quickly while the boat sails itself. I do notice that it starts to head up more as the keel goes down (CLR moves forward, CE pretty far back due to only having main up).

I will try raising the keel a little if weather helm builds up. That is a good idea.
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post #10 of 11 Old 09-30-2009
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Do you have a GPS?

The amount of sideslip will vary with the wind strength and probably get worse when trying to point.

If you have a GPS you might try a similar experiment under different wind conditions: Sail a known heading using the boats compass and seeing the course you are actually sailing on the GPS. Raise and lower the keel to see how it affects the course made good. The GPS experiment will give you an idea of the varying slip in the differing winds.

I think you are probably near the Agonic line (0 magnetic declination) but make sure the GPS is set to magnetic north anyways to not get a false sense of drift.

Jordan
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