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Discussion Starter #1
I'm looking for some advice on what's going on with my boat. I have a 23' swing keel boat with a wood rudder. When sailing at a close reach, the rudder has little authority. When we get hit with a gust of wind (10-15kts), the boat comes about, tiller hard to windward.

I'm wondering if I've got something trimmed wrong? The previous owner had no experience sailing her, so was not able to offer rigging advice. I'm wondering iof there's something wrong with the rudder; it's pretty thick teak with the leading and trainling edges fairly blunt.
 

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It would help if you said what 23' swing keel boat you have, since different ones have different issues.

It would also help if you said what sails you have up. Photos of the rudder wouldn't hurt either. I'd highly recommend you read this POST to help you get the most out of sailnet.
 

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I've never sail a swing keel boat, but if I understand your situation correctly it is apparent that your center of effort (CE) is behind (abaft of) your center of lateral resistance (CLR).

Center of Lateral Resistance: There is a point on the side of the boat where the boat may be pushed sideways in the water. It may be pushed sideways in the water at this theoretical point and will neither round up nor fall off. With your swing keel, the point is adjustable. So the first question is: Is your keel staying put or is it swinging back up under the boat as you sail?

Center of Effort (CE): Those are your sails. If I were to sail your boat under main only the CE would probably be too far aft. That would cause the boat to round up in gusts as you describe. Or, maybe if I had the main trimmed too tight I would cause the same thing. So the second consideration is: Is there something about the way that you are trimming the sails that is moving CE too far back?

What do you think so far?
 

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You are probably describing rounding up into the wind. When overpowered most boats are designed to do this to some extent, as the hull shape underwater changes and less rudder may be underwater with excessive heeling.
However yours sounds excessive. The rudder could stall when hard over more so with a less aerodynamic shape. However the primary problem is likely to be sail imbalance. That is too much power behind the mast rather than in front. Actually it is before and after the point of lateral resistance but you have two sails to adjust.
You should be able to handle 10-15 knots easily but I wonder if this is the actual apparent wind, which is raised by the boat speed. Normally you adjust to get a balanced sailplan, with a slight windward helm.
You may find you need to flatten the main effectively by increasing tension on it. You may have the main sheeted too tight and the jib too free. You may need to let the traveller down, or without one ease the main in gusts.
IF the true wind speed is 10 then you will get gusts to 15 but with boat speed actually have 20 or so and need a reef or to use your cunningham.
Generally you will get better speed by sailing the boat flat or with at most 20 deg heel. I suspect that you are heeled hard over which will give excessive helm but the problem arises before that.
 

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John,
I've a swing keel boat myself and I doubt that it is anything related to the keel unless, for some reason, you have not lowered it all the way.

I would suggest that you begin with tuning or adjusting your rig. You'll never get either good performance nor consistent performance if your rig is not properly set. There are numerous articles on the practice, many here, and you could do far worse than to watch one of Giulietta's videos here: http://www.sailnet.com/forums/gear-maintenance/42542-adjusting-your-rig.html

I'd recommend the purchase of a Loos guage; the less expensive manual one will do versus the "Pro" so that you can repeatable results, especially important if you're trailer-sailing your boat.

Once your rig is adjusted you can adjust the points of sail trim which Giulietta covers in other videos found here as well.

Your rig may be tuned adequately and you may just have your sails out of adjustment. I would mention that my Cal 21 is easily over-powered, which is not a curse as I sail her in light air that has everyone else either not sailing or depressed about their lack of motivation (g), and if I fail to reef the main I will get excessive weather helm. You can determine if you have a main sail issue in your case by slacking the main sheet when the condition occurs and see how that effects your rounding up. If, as in my Cal, you're sailing on your ear, heeled over about thirty degrees, you're carrying too much main sail. The rudder is hard over and just causing drag as the boat proceeds to round up. That, ironically, is what is supposed to happen; the alternative being you take a very large bath! If that is the case, you're over-powered, despite what other boats are carrying for sail (!), and you need to reduce sail. The good news, in my case, is that I can sail under a reefed main just as fast. Check your rig, including your mast alignment and then play with the sail trim.
 

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I am pretty sure you are experiencing lots of weather helm and, as said previously, also being overpowered. After checking the rig tune, you need to learn how to depower by sail trim and/or reducing sail area.
 

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Unless I am mistaken, you are experiencing weather helm which is normal when the wind is overpowering the way you have the sails set. Ease off on the sails.

Harris
 

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I'm thinking exactly what JimsCal said. All of those things can produce excess/early weather helm and yes, 15 knots is more than enough to reef some boats. With gusts of 10-15 knots you may very well need to constantly play the traveler (assuming you have one) to keep that boat on its feet and prevent it from rounding up that way.

Some boats also round up early because they have shallow draft rudders, which come out of the water (so to speak) very quickly as the boat heels, leaving you without any effective wetted rudder area. That can be a design flaw but again, rig and trim are how you'd fix that normally.
 

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I have to set the first reef point or lay off the main right around 12 knots true...sounds like you are getting weather helm
 

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I also have a swing keel.. We had a problem with the line that held our swing rudder in the down position.. it would drift up and do what you describe with just a 5deg heel.. I was constantly stepping over the back of the boat and pushing the rudder straight down.. finally got around to drilling out and replacing the line, Problem Solved !!
 

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The advice so far is missing something. Your rudder is losing flow easily. Could be bad design. When you lose flow the rudder stalls and you round up=no fun. As a work around, try pumping the tiller hard several times and I mean hard as soon as you start to feel a puff. This should help reattach the flow. Short term solution to what might be a long term problem.
 

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Another variable that could be causing you to 'round up is how full your mainsail is. A bellying sail on a reach, especially if it's bellying at the top, creates a lot of pull, and can swing your center of effort (there's that expression again!) behind your center of lateral resistance. In a centerboard boat, raising the board a bit could help balance the two forces better. In your case, with a swing keel being (you hope) fixed down, tightening the boom vang might help flatten the sail and reduce the heeling moment that may be swinging you into the wind. Cranking in the vang when on a reach might be worth trying. Let us know what works!
 

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Discussion Starter #14
Thanks for all of the great responses! It could be that what I'm experiencing is simply weatherhelm. 20 years ago I spent a lot of time sailing my Flying Scot. My International 23 is a very different boat. I'll have to spend more time sailing her and figuring this out.

The weatherhelm does occur when pointing up into the wind and the sheets pulled tight, we start to heel more than 15*, get a gust of wind and around she goes! I probably need to start letting the sheets out when the wind picks up.
 

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As stated above, you are experiencing Weather Helm. This is where the boat wants to turn itself into the wind while sailing/heeling. The opposite is Lee Helm where the boat wants to turn "away" or "down" wind while sailing/heeling. This is a Sail/Mast/Rig Tune Up problem. It may also be a result of your swing keel not being lower properly or all the way down in the keel/centerboard trunk.
1) Make sure your mast is vertical side-to-side. Duct tape a tape measure to your Main Halyard. Hoist the tape and halyard up to the top of the mast. Place the lower end of the tape measure at the base of your side stay/shroud turn buckle on the Starboard side. Make note of the measurement. Do the same on the Port turn buckle. Is the measurement the same? If not, adjust your side stays until the measurements match. Once done, you are confident the mast of vertical side-to-side.
2) Adjust the mast Fore and Aft (front to back). If you are experiencing Weather Helm (where you must put the tiller to windward while sailing in order to keep the boat from rounding up into the wind) you need to tilt the entire mast rig Forward. Experiment until the weather helm stops. This means loosening your backstay(s) and shrouds and tightening the forestay a 1/4 or so at a time until the boat is tuned and the weather helm all but dissapears. What is ideal? When there is just a slight bit of weather helm. Some weather helm is necessary as a safety element; if you really get knocked by a blow, you want the boat to round up into the wind and luff to safety.
3) Also check your swing keel. All of the above is to be done with the swing keel lowered all the way down. If it is stuck, the boat will not sail or perform as designed. If you have clear water, lower the keel and swim under the hull with a dive mask and inspect to make sure the keel is all the way down. Finally, and if you ahave a "kick up" rudder that it remains in the down position while underway. They sometimes tend to lift up at higher speeds. This will greatly effect your Tuned Boat performance. Be sure rudder is locked in the down position.
P.S. These elements of tuning effect what is called Center of Lateral Resistance (CLR). If you want more technical specifics read about CLR in a good sailing book.

A finely tuned boat nearly eliminates skipper fatigue at the helm and is a joy to sail!
 

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Discussion Starter #16
Thank you BradleyK!!

I'm certain my keel is all the way down, so I'll check into the other things you detailed. Thanks again!
 

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Most swing keels swing down and forward; if they aren't lowered all the way, the boat will exhibit LEE helm rather than WEATHER helm. The nose will head DOWN. On badly overpowered, mainsail-biased boats like our Bucc18, the swing centerboard must be raised about halfway to stop it rounding up in higher winds -- it moves the CLR aft. This is not always a good idea on boats with ballasted swing keels, however. Depends on the boat.

You say the rounding occurs on a "close reach". That's interesting. You may indeed be stalling the main. Try sheeting out until the luff pocket gets 'soft'. Oversheeting on reaches is a common practise. Trim the jib to the wind and the main to the jib.

Does your main have reef points? I bet your boat would behave very well with about 40" taken out of the foot of the main. May even sail faster, because fighting the tiller is SLOW. Fifteen knots is about where we reef the SJ21, and the helm goes right back to neutral. As others have mentioned, your rudder may be damaged or of a non-foil design. I've seen some that are just slabs of wood; knew one guy who couldn't get his boat to steer because the PO had bolted the rudder blade on backwards! A rudder that is inefficient requires more aggressive tiller work, which leads to stalling and flow that detaches too early. Kind of a feedback loop.:(

One possibility that hasn't been mentioned is hull trim. Does your boat sit level on her lines? If she is down in the bows (like if you just added a bunch of anchor chain or are sailing below designed crew weight) she will tend to dig in up front & slew wide at the stern. Subtly different feel than a rounding up. Let us know what you figure out!
 
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