Weather Helm
- Thread starter captain cajun
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Adding to the rudder size in general will move the center of lateral resistance aft, which is effectively moving the center of effort forward, so yes, it will help remove weather helm. If the rudder is an unbalanced design, adding rudder area forward of the stock will help balance the rudder a bit better.
CLR calculations
While I agree with saildog I would have to note that the rudder can be set to provide different forces. That is what saildog is talking about when he is saying it will effect the Center of Lateral Resistance (CLR). The CLR is the sum of keel and rudder but the rudder is a variable force however. You use the rudder to counteract all turning forces from the sails that would cause the boat to turn off course. All those turning forces can be considered to act around the keel. In a balanced boat the rudder is designed to have around 3 degrees of weather helm. That is, the rudder will be acting with the keel to produce a resistive force directed windward. Increasing the size of the rudder will only allow you to achieve a balanced boat with less angle on the rudder it will not get rid of the cause of weather helm.
So if you have to give quite a bit of rudder to counteract the sails weather helm then, yes an increase in rudder area (fore, aft, or draft) will help reduce the amount of helm you need to apply to achieve the same resistive force. Making the rudder wider is not the best solution from a drag standpoint. If you can make the rudder longer it will increase the aspect ratio of the rudder making it a more efficient foil
I'm not sure why you would want to "fix" it this way. What is causing the weather helm in the first place. Sail balance is VERY important and can cure most of these problems. Have you tried ease the main or power up the jib to correct weather helm?
While I agree with saildog I would have to note that the rudder can be set to provide different forces. That is what saildog is talking about when he is saying it will effect the Center of Lateral Resistance (CLR). The CLR is the sum of keel and rudder but the rudder is a variable force however. You use the rudder to counteract all turning forces from the sails that would cause the boat to turn off course. All those turning forces can be considered to act around the keel. In a balanced boat the rudder is designed to have around 3 degrees of weather helm. That is, the rudder will be acting with the keel to produce a resistive force directed windward. Increasing the size of the rudder will only allow you to achieve a balanced boat with less angle on the rudder it will not get rid of the cause of weather helm.
So if you have to give quite a bit of rudder to counteract the sails weather helm then, yes an increase in rudder area (fore, aft, or draft) will help reduce the amount of helm you need to apply to achieve the same resistive force. Making the rudder wider is not the best solution from a drag standpoint. If you can make the rudder longer it will increase the aspect ratio of the rudder making it a more efficient foil
I'm not sure why you would want to "fix" it this way. What is causing the weather helm in the first place. Sail balance is VERY important and can cure most of these problems. Have you tried ease the main or power up the jib to correct weather helm?
I second Bill's suggestion that you try working with your sail trim first - easing the main or powering up the jib. I was lucky when I was learning to sail, an experinced sailor told me that it was possible to steer the boat using sail trim and explained how that worked. As a secondary benefit, playing with your sail trim might also allow you to sail flatter and faster.
Jim Kolstoe, h23 Kara's Boo
Jim Kolstoe, h23 Kara's Boo
I have a kick-up rudder on my boat and find that I have to be certain the rudder is held down all the way or I'll experience some weather helm.
I found that when I reduced the mast rake on my boat I almost eliminated weather helm. As I added better sail controls to flatten the sails as the wind picked up things have continued to improve in conditions of higher winds. I also installed an Ida Sailor rudder, much improved.
I have a swing center board on my boat and just read a book that advises moving the center board up slightly to move the center of lateral resistance back to reduce weather helm, I had already noticed this effect myself.
The author further advises "beating in strong wind, a boat with its center board slightly up is phenomenally faster and easier to sail than a boat with the board all the way down". I have not tried this yet but am looking forward to trying it the summer.
Bob
I found that when I reduced the mast rake on my boat I almost eliminated weather helm. As I added better sail controls to flatten the sails as the wind picked up things have continued to improve in conditions of higher winds. I also installed an Ida Sailor rudder, much improved.
I have a swing center board on my boat and just read a book that advises moving the center board up slightly to move the center of lateral resistance back to reduce weather helm, I had already noticed this effect myself.
The author further advises "beating in strong wind, a boat with its center board slightly up is phenomenally faster and easier to sail than a boat with the board all the way down". I have not tried this yet but am looking forward to trying it the summer.
Bob
Thanks all, these are the things I am reading about while waiting for spring to try out. Knowledge said many different ways, sometimes gets thru. Now, information on how to make spring come sooner in Colorado. <grin>
It has all been said in different ways but play with sail trim to balance the helm. Not only can you trim the sail in you can also ease them. Often it doesn't take much just a few inches can make a noticeable difference in helm balance.
about a day's drive to the southeast, and you can sail on whatever lake has enough water in it for your tastes. you can sail every weekend down here somewhere. shoot, a big deal for us is to head your way in the summers so we don't cook our behunkeses in the cockpits. btw - i hear they've been sailing pretty regularly over at elephant butte, new mexico. sure is tempting to just head that way... jack b
in midland, tx usa- Status