weather helm & boom position

[Don Guillette]

Mates: I was talking to a sail trim lister this morning. He was embarressed to ask the questions on the Forum because he thought others would think his questions were silly. I wish that would not happen but I know it does and that is too bad.Since he had the questions I know other beginners to intermediates might also.His first question was regarding the boom position in relation to the centerline of the boat. He told me he makes a conscious effort never to go beyond the center line. My response was to "let it all hang out" and forget the general rule that you should not position the boom beyond the center line. On my C30, if I went beyond the center line I could feel the boat lose power but on a Newport 30 I raced on by going past the center line I could squeeze a little bit of power out of the main. So the bottom line is experiment and see what works for you.His next question involved weather helm. He told me he hates weather helm and constantly fights to get rid of it. Big mistake as weather helm is your friend. If you refer to my Sail Trim Chart you would note that the last step in adjusting the main and jib for 100% efficiency is to induce 3 to 5 degrees of weather helm. Why would anyone want to do that? The answer is because of LIFT. Lift, which is what powers the boat, is generated from the sails, keel and rudder. Most sailors don't consider the rudder as a lifting agent but it is. The 3 to 5 degress of weather helm I induce to the rudder by adjusting the traveler makes the boat go faster. Next time your out sailing try my suggestion. First get the boat going at full speed with a neutral rudder. Next induce some weather helm by adjusting the traveler and see if the boat picks up speed. You won't set the worlds water speed record but there should be an increase in your speed.

 

[NewportVic]

Center line boom may not be the right rule.

It might just be the active center leech of the sail that really is the key. With twist the boom might well be somewhat past the center line? then again if you have more than enough wind to hit hull speed ... can you try to fine tune pointing a couple of degrees?Vic "Seven"

 

[Bob]

great topic!

Boom position close-hauled came up in a discussion I had recently with a very knowledgable racer/sail builder. I mentioned that many authorities talk about bringing the boom no higher than the boat's centerline. He reacted strongly, asking me where in the world I got that info. So I gave him quotes from Conner, Elvstrom, Ross (author of "Sail Power"), etc. Indeed, their writings give the impression that bringing the boom above center is a rigid taboo. But he gave me numerous examples of when it was advantageous to get the boom a little higher, citing specific boats that used this technique. The old, "classic" view was that any hook in the main that angles back to windward creates a vector that acts against the forward motion of the boat. His point was that this 'over-center' location is allowable if it allows the foresail to counteract that "backward" vector with an even stronger forward one. And this would result in the increase in speed that Don mentions. Even more important, as far as he was concerned, was that bringing the boom up helps the boat to point higher with very little if any loss of speed, as Vic indicates. I have tried this in competition and found it to work well - I'm pointing higher than in the past, with very little drop off in speed. And sometimes, close to the weather mark, bringing the boom up allows us to shoot the mark when otherwise we would have to throw in an extra tack. So as long as the boat is moving well and the tell-tales indicate good flow off the leech, I don't worry nearly as much about bringing the boom up as I used to.

 

[Phil]

Where's the Sweet Spot

Years ago I sail a friends C30 and was able to find the boats sweet spot. By that I mean the trim and rudder position where the boat would round up a little in the gusts and fall off a little in the calm. You almost didn't need to sali the boat, it sailed it self. I now have a C350 and can not for the life of me find the sweet spot. I am wondering if the boat may not have such a spot due to it hull design, fat. Thoughts?

 

[Don Guillette]

Topic

Bob: I guess I'm in the same company as your friend. A boat is like a woman - I've yet to meet two that are the same and you have to feel them out to get the most response from them. Just like a boat. Each boat has so many factors that you really have to spend some time and mess with them until you find the right SPOT for each point of sail and wind condition. It takes a little time but the results are worth.The most import things you have to understand is draft depth, draft position, twist and angle of attack. Once you understand those 4 things sail trim is actually a snap.

 

[Don Guillette]

Sweet Spot

Phil: The C35 does have the spot your looking for. You have just not found it. I could set up my C30 to sail by itself. Some times I just wanted to kick back and smell the roses and tip a "tinney" while I watched the world sail by but if I wanted to get 100% performance out of the boat I would have to go past the sweet spot and pick up some lift from the rudder.As I mentioned all boats are different but if you get your boat set up properly for closehauled the trick I found for the sweet spot was moving the traveler. All it takes is a little movement one way or the other. Go through the mainsail and jib set up sequence I outline in my Sail Trim Chart to get you boat perfect and then disregard the last step, which tells you to induce 3 to 5 degrees of weather helm.

 

[oldiesrocker2001]

another question on weather helm

Not that I'm tryin to take over this thread, but I have an excessive amount of weather helm on my old V21. I experience this most of the time (even a bit under power at speed)it seems that the down haul which is a heavy shock cord, i imagine to prevent real damage in a grounding, can't seem to hold it down. I know that after stopped for a while, the rudder fills with water(intentional?) and will stay down until we're at speed again. when possible, I have the rudder all the way down. The backstay is usually a bit slack under sail. Should I try to induce more rake by loosening the forestay(furling jib) and going another notch on the back stay? Any suggestions?

 

[oldiesrocker2001]

Keel, not rudder

My Mistake, I meant to say that I keep the Keel all the way down whenever possible. the shock cord on the rudder downhaul is new...

 

[Joe]

lock the rudder down....

you should be able to lock the rudder in the down position with a pin or a control line. If you can't it's not rigged right. Same thing with the centerboard. Flowing water pressure will cause it to rise. When it's still, the rudder sinks back to it's proper position. Usually a bungy cord is to help raise the rudder when you pull the pin as you beach the boat. More mast rake means more weather helm. Old sails that are baggy and can't be flattened will induce weather helm. Drop the traveller and spill off some air with the mainsheet to take some pressure off the mainsail. Flatten the sail by pulling all the strings: halyard, outhaul, cunningham, backstay (to bend the mast). If that doesn't worke because it's all stretched out, take the sail to a sailmaker and have him re-cut it to a better shape.