Rudder Trim (Up or Down)

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Rudder Trim (Up or Down)

Postby algonquin » Sun Oct 07, 2007 8:02 pm

My first voyages in my DS1 this summer found me forgetting to put the rudder in the down position while sailing. In one instance the winds were averaging 10-12 knots with gusts to 18.

I was sailing for more than an hour in those winds when I realized the I had not released the line that allows the rudder to go vertical. The boat was handling exceptionally well despite my oversite. I was able to sail to all points of the wind with no significant issues as to weather or lee helm. I put the rudder in the vertical and felt that I did not have the same comfort of control and actually it seemed more difficult to maintain course.

My last boat was a Magregor 23 Venture Newport (cutter rig) and it also handled well with the rudder in the up position so that is how I left it for nearly every outing.

I was surprised that the DS1 seemed to handle better with the rudder up because the boat is so light.

Looking for opinions and experiences of other DS owners on this subject.
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rudder up=more stress on tiller

Postby Roger » Mon Oct 08, 2007 11:05 pm

You do get a more responsive boat, but the price you pay is fatigue, slightly decreased speed, and more stress on the rudder and tiller pivots includling the gudgeons and pintles.
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Re: rudder up=more stress on tiller

Postby algonquin » Mon Oct 08, 2007 11:35 pm

Roger wrote:You do get a more responsive boat, but the price you pay is fatigue, slightly decreased speed, and more stress on the rudder and tiller pivots includling the gudgeons and pintles.


I understand what you are saying and agree in theory. I really didn't feel like I was putting any more strain on the tiller at all or feel like I had to muscle the tiller. There was no increased resistence. Possibly the sail trim was just right.
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Postby jpclowes » Wed Oct 10, 2007 4:23 am

It might not have been a concern when you were sailing, but the shape of your rudder, in its normal position should help your pointing ability. With the rudder in the up position, you probably couldn't point as close to the wind. The rudder should be shaped like an airplane wing, and provide lift, which helps you point. With it in the up position, its shape won't provide lift.
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Postby algonquin » Wed Oct 10, 2007 11:15 pm

jpclowes wrote:It might not have been a concern when you were sailing, but the shape of your rudder, in its normal position should help your pointing ability. With the rudder in the up position, you probably couldn't point as close to the wind. The rudder should be shaped like an airplane wing, and provide lift, which helps you point. With it in the up position, its shape won't provide lift.


You have made a definate point made based on sound sailing science. I hope to get back in the water next week and will check it out.
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decreased speed

Postby Roger » Thu Oct 11, 2007 1:09 am

The point I was attempting to make regarding decreased speed is thus. If your rudder is in the up positon and deflected 3 degrees off center to compensate for weather helm, that three degrees extends out further creating increased drag thereby slowing you down. If on the other hand the rudder is down, the same wetted surface strikes the rudder face, and although the rudder angle may still be 3 degrees there is less lateral force (leverage) at the trailing edge of the rudder which is now closer to the transom.
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Postby Phill » Sat Oct 13, 2007 1:26 pm

Rudder vertical or slightly, < 20dg, raked.

The DS rudder is a short/shallow one in the first place. When you heel, the wide hull that makes our boats so stable, lifts the rudder and it will wash out and become ineffective. If you rake the rudder too far, it is usless when you need it most.

If you feel the boat is better balanced, ie not too much weather helm, when the rudder is raked, then you will need to use less mast rake, more leech tension to get the most out of your boat upwind.

The DS sould be set up so that when the rudder and CB fully down, saiiling upwind with the sails set to optimum, 6-8 winds, boat FLAT (no heel) there should be very slight weather helm. If you let go of the tiller the boat should start a SLOW turn toward the wind. If it tries to turn fast or snaps toward the wind you need less mast rake, shorter forestay.

Hope this helps

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Postby algonquin » Sun Oct 14, 2007 12:09 am

Great info here. Thanks Phill for the further clarification. Good point about the rudder position when the boat is heeled. I can attest that with the rudder in the "up" position and the boat heeled there is little control as you mentioned.

As I indicated at the start of this thread this is my first summer sailing a DS1 and although I have had other larger sail boats I have found the DS1 to be very sensitive to sail trim, rigging tune, and rudder/CB position. Also to the positioning of the on board ballast - ME - . :lol:

Looking forward to learning more. I don't have plans for racing but want to learn how to optimize my boats performance. This forum is a great place to do it.
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Postby Bob Hunkins » Sun Oct 14, 2007 9:38 am

At the risk of proselytizing, I'll say that the best way to learn to optimize your performance is to race. Most races are not cut-throat affairs. It has been said that when two boats or more are on the water at the same time it's a race. :wink:
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Postby algonquin » Sun Oct 14, 2007 5:30 pm

Bob Hunkins wrote:At the risk of proselytizing, I'll say that the best way to learn to optimize your performance is to race. Most races are not cut-throat affairs. It has been said that when two boats or more are on the water at the same time it's a race. :wink:


:lol: I have to agree with you. Two boats is a race and a chance to test your skill. I don't plan to enter into sanctioned competition, mostly because there are almost no other DS owners within at least 50 miles or more of me. Its a shame because the lakes in my area of Maine are large and pristine with low boat traffic. Generally small fishing boats and often the only boat turns out to be the one you are in.

I have entered my DS1 for 3 ragattas next year at East Grand Lake on the New Brunswick Canada border. There will be about 16-18 sail boats of many different shapes and sizes and you "race" in an open "run what you brung" fun competition that is mostly fellowship followed by an afternoon of BBQ and bragging :wink: .

Hope to get quite a bit more time in my DS1 this fall and early spring to
learn to optimize my performance at the helm of "Feather" before the first ragatta.
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Re: Rudder Trim (Up or Down)

Postby Tipster1 » Sun Sep 22, 2013 9:23 am

I don't know if anyone is still monitoring this conversation, but, I have a question.
Day before yesterday I wen sailing in 10-12 knots and, just to get to know boat better, I tried main only. What I found was that, with cb and rudder all the way down, boat seemed to point well, but there was a pretty strong weather helm, no doubt due to center-of-effort being well behind center-of-lateral-resistance. The boat went into irons easily and getting out of the situation required backing around almost to a broad reach before sheeting in. Slight (25-50% - no way to know for sure) raising of CB moved CLR aft and weather helm disappeared. Rudder effectiveness still poor.

After retrieving I mounted rudder and discovered that rudder actually has slight forward rake (see picture) when pushed to the lowered position.

1671

Is this intentional?
Does anyone else have this?

I am considering fashioning a shim or stopper to make max lowered position vertical, unless there is a good reason.
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Re: Rudder Trim (Up or Down)

Postby GreenLake » Sun Sep 22, 2013 4:07 pm

Tipster1 wrote:I don't know if anyone is still monitoring this conversation.


Now they will :)

I guess it's a reasonable enough extension so we can recycle this conversation.

To come to your point. I've seen this on my rudder as well.

Try a shim and see whether you observe a change. My money is on there not being any difference at the angle you observe.

A forward rake would change the rudder profile to be wider (the ratio of depth to the length of the water's path across the foil would be longer. And by being forward, the lever arm between CB and rudder would be slightly shorter, so rudder movements are that much less effective. Are these two effects large enough to be measurable? You find out.
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Re: Rudder Trim (Up or Down)

Postby jdoorly » Sun Sep 22, 2013 11:58 pm

As the rudder moves forward relative to the pintles (i.e. the axis of rotation), especially if there is a substantial percentage of the rudder area involved, say 10 to 30% then the steering should take less effort because the rudder becomes less of a "barn door" and more of an efficient "balanced spade" type rudder.
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Re: Rudder Trim (Up or Down)

Postby Tipster1 » Mon Sep 23, 2013 12:25 pm

One more thing to play with. What I have noticed in sailing other boats is that you can wag the tail of the boat almost in a pumping rhythm when you get stuck. You can even sort of skull a boat a few extra feet when you are just short of a mooring. With the rudder config I had, there was no leverage to do this. I will eventually (next spring?) put a shim in the space inside the slot where the rudder swivels to see how it feels, after I install rudder up and down lines and eliminate friction as main means of rudder control.
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Re: Rudder Trim (Up or Down)

Postby ChrisB » Mon Sep 23, 2013 1:53 pm

When I push my rudder all the way down to the "stop" it too has a slight forward rake. When fully down in this position, the boat is very responsive and little effort is required for steering. If the rudder is anything short of against the stop, the level of steering effort increases significantly.
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