Tiller question

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Tiller question

Postby jsbowman6 » Sat Jul 23, 2016 7:54 pm

I notice my rudder is kicked up while sailing in deep waters. I have to push it back down from time to time. Is this just the nature of the beast?
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Re: Tiller question

Postby GreenLake » Sat Jul 23, 2016 8:45 pm

In short, yes.

In lighter/moderate winds it may be enough to tighten the pivot bolt some, but if you sail rather fast a lot, you may want to rig a line to act as a rudder downhaul.
~ green ~ lake ~ ~
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Re: Tiller question

Postby jsbowman6 » Sat Jul 23, 2016 10:00 pm

Has anyone ever put a weight in or on the rudder so only an uphaul is used? Take that one step futher, how about the same to the center board? That would let you get rid of that rube goldberg setup for the CB. If so how did you do it. I don't intend to race this boat.
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Re: Tiller question

Postby jeadstx » Sun Jul 24, 2016 1:42 am

I have a downhaul line for my rudder blade and use an auto release cleat to allow it to pop up if I hit something. If you don't want a downhaul, you could also try to tighten the bolt more to create more friction, but leave some movement.

John
1976 Day Sailer II, #8075 - Completed the 2011, 2012, and 2013 Texas 200
1952 Beetle Boat Swan Catboat
Early Rhodes 19
1973 Mariner 2+2, #2607 - Completed 2014, 2015 and 2016 Texas 200
1969 Day Sailer I, #3229
Fleet 135; Canyon Lake, Texas
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Re: Tiller question

Postby GreenLake » Sun Jul 24, 2016 3:50 am

I'm still waiting for the part of the question that's about the tiller. :)

We know of at least one DS that has been mentioned here in the forum, where somebody replaced the CB with a steel plate.

The problem is that a flat steel plate is hydrodynamically even less effective than the stock CB, which is already a bit marginal for the boat. You might get some righting moment, but probably only significant at higher angles (close to or after capsizing).

For the rudder, adding weight is not a sensible solution. One, you don't want extra weight at the back of the boat. The more your transom dips below the waterline, the slower you will sail. Like having the parking brake engaged. Second, if you get up near hull-speed, let alone planing (but you are not intending to race) the force on the rudder is substantial. Let's say it's 10 pounds, pushing aft, with a lever arm of about a foot (half the depth of the rudder).

A weight in the rudder would have to have some lever arm. Either you mount the weight all the way aft, then you have a lever arm of about 4". So you need 30lbs or more to counteract the rudder force. The problem, that hydrodynamic force goes up with the square of the velocity. So, it takes very little extra speed to add a lot of extra force, meaning, if you want to be sure that the rudder stays down, you'd have to give it a good margin, perhaps double.

At that point, you need to remember the thing about why you don't want extra weight at the back of the boat.

Tightening the pivot bolt usually works for me; my weekly outings are at times and locations where I'm lucky to get enough wind to sail fast. But it's marginal, for the same reasons I gave above: the amount of resistance by the pivot bolt is fixed, while the force curve goes up rapidly with speed. One extra-strong gust, and the friction of the bolt may not be sufficient. A proper downhaul (with a clet that releases on overload from ground contact) would be the solution. As long as I'm getting by, I probably won't bother rigging one.

I've never seen the need to rig an uphaul. I beach the boat infrequently, and simply let the rudder kick up on contact (and then remove it entirely).
~ green ~ lake ~ ~
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Re: Tiller question

Postby jsbowman6 » Sun Jul 24, 2016 7:46 am

GreenLake wrote:I'm still waiting for the part of the question that's about the tiller. :)


Greenlake you caught me! I'm bad to call the rudder the tiller :shock:
Anyway I appreciate all the responses. I'll try to tighten the bolt, it's pretty loose.
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Re: Tiller question

Postby Baysailer » Sun Jul 24, 2016 11:00 am

You could drill a small (1/8" or so) hole through the rudder head and rudder in the down position as a keeper. Use a softwood dowel as a pin. It has to be small enough so it would break if you hit something hard. I am making a fixed rudder, non kick=up, for deeper water use since that is mostly what I do.
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