Re: Question #2 (Error)

[Don Guillette]

Quetion #2 (error)

Sinbad: I'll bet you aced this quiz!! The problem we encountered developing this quiz was it is easier to sail the boat than make up a quiz!!Your correct with your observation. To explain to the rest of the folks what we were trying to get at with that question is that there are two sail trim controls that regulate twist in the mainsail and they are the mainsheet and the boom vang. Increasing tension on either REDUCES twist and easing tension INCREASES twist.For those of you that may not know what twist is or looks like, hang on and I'll be right with you shortly.

 

[Sinbad]

I don't remember the exact wording of the question, but it gave a choice of 3 answers. Each answer refered to more or less mainsheet tension. After each answer there was a note in ( ). The note refered to the amount of twist in the main. For example: high mainsheet tesnsion (large twist). Of course, high mainsheet tension means less twist not more. I understand the goal of the question, but I think the error made it misleading.

 

[Matthew Percy]

why some people win and some lose

Well done, I can sail very well. I dont go as well in the quiz, maybe I should read more and sail less. No that wont be as much fun. Your Q how often do you go near your boat in winter? Winter is the best time to sail its not as hot and the ice last longer so you can drink more beer gotta luv where you live.

 

[francis]

twist vs tension

don, I have your book and have read it many times. Sometimes I think I have it down, then some times it seems to contradict itself.Can you please explain this again. I get confused. You say that when you increase tension on your mainsheet you reduce twist and easing tension increases twist. I understand that, but then in your book you say that in heavy winds you should add twist to your sails to drop air, and that you should put tension on the lines to flaten the sails. But to flatten your sails by increasing tension aren't you reduding twist instead of giving more twist like you had said in the above post? That statement has always confused me. It's like to reduce power you put twist into the sail, but when you flatten the sail for high winds, you are actually taking twist away instead of adding twist. I think I need more explanination of this.Thanks

 

[Don Guillette]

Twist vs tension

Francis: Let's see if I can clear up what I was trying to get at. The problem is that at first it is not easy to understand because we are dealing with a bunch of things but once the light goes on it becomes clear. TWIST is the primary "braking system" for the main and jib because you are depowering the sails by spilling air out of the top 1/3. In heavy wind, another "braking system" is a flat sail with no draft depth because a completely flat sail lacks power. The power for the main and jib comes mainly from draft depth and draft position just like flaps on a plane provide power for landing and take off. Angle of attack and lack of twist also come into play. In other words, everything has to work together. That is why there are so many controls for each sail. What I'm trying to say is probably best shown in an example of how I would sail a CRUISING boat through the full range of wind from very light to heavy. As a note, if I were racing the boat I would do it differently as I want all the power I can get from both sails.Starting out with very light air, I want the sail as flat (no draft depth) as possable because the wind does not have the power to get around the sail. As the wind start to pick up, I am gradually and slowly inducing draft depth plus keeping the draft position at between 45% and 55%. I'll keep inducing draft depth until I get to about 25% to 30% plus holding the draft position. I proceed this way up to about 12 to 13 knots of wind continually adjusting the controls and watching the telltails. Additionally, all this time I'm trying to keep the boat on its feet with about 12 to 15 degrees of heel. At about 13 knots of wind, I'm going to start backing off on the draft depth and I'll start pushing the draft position forward because draft position forward produces less power. Additionally, I'm going to start inducing twist into both sails. I'll also drop the traveler a bit. There will come a point in time, as the wind increases, that all the twist in the world isn't going to help and that is just before it is time to reef but before I get to that point where I have to reef I have abandoned twist and will get the sail as flat as possable (no draft depth) and see if I can still control the boat.I hope I have made myself clear. If we were sitting on your boat or out sailing it would be so much simplier to explain this stuff and as you asked a couple of questions you would see what I'm getting at. If you have any other questions, just fire away.