Let's talk about TWIST. First of all, what is it? It is the leeward sag of the leech of the sail. It is easy to spot on the water as 75% of the sailors sail with it all the time. To see it, stand in your cockpit and view the leech of the sail from top to bottom. If your sailing close hauled, the top half of the sail will look as if it is sailing on a beam reach and the bottom portion will appear to be sailing close hauled. Why do we have to deal with TWIST in the first place? The answer is because there is more wind at the top of the sail than at the bottom. The wind blows 60% greater at the top of a 40' mast than at deck level and the reason is FRICTION. When wind blows across the surface of the water it slows down, so stronger winds aloft necessitates some twist in the sail and sail makers design some twist into their sails, but to get 100% efficiency from your mainsail, it has to be as even as possible from top to bottom. In other words, you can't allow the top of the sail to be on a beam reach and the bottom close hauled. To compensate for this problem, the top of the sail needs to be eased as if on a close reach and the bottom has to be trimmed hard as if on a beat. Without sail trim controls, you could not make the twist adjustment. As a note, a lot of sailors think there is a CRUISING way and a RACING way to sail a sailboat. Actually, there is zero difference between the two and only a RIGHT way and a WRONG way to sail a sailboat. Think of TWIST as "power off" (brake) and "power on" (accelerator). The MORE leeward sag you have in your mainsail the LESS power you are generating because air is spilling out of the top of the sail. The LESS leeward sag or the straighter the leech, the MORE power you are developing because you are containing the wind in the top of the sail and generating power. You may have to read this paragraph a few times to understand what I'm trying to say. Fine tuning TWIST is the most important sail trim adjustment you can make. The sail trim controls used to adjust twist in the mainsail are the MAINSHEET and the BOOM VANG. INCREASING tension on these controls REMOVES twist and DECREASING tension ADDS twist. The next time your out sailing, experiment with these controls and see what happens. Follow these easy steps: Step 1 Sail close hauled Step 2 Position traveler so boom is near center Step 3 Trim mainsheet until top batten is parallel to boom Top batten can point slightly to weather Top telltail should stream - if it curls, ease sheet Step 4 Ease traveler down Top breaks first - trim sheet in (too much twist) Bottom breaks first - ease sheet out ( not enough twist) Step 5 Twist is now set Step 6 Pull traveler up to obtain 3 to 5 degrees weather helm on rudder. Any questions?
- Status
- Not open for further replies.
M
MJ
Yes
1. When does the down haul or cunningham figure into decreasing or increasing twist; or does it? 2. When is it appropriate to increase twist? Thanks.
1. When does the down haul or cunningham figure into decreasing or increasing twist; or does it? 2. When is it appropriate to increase twist? Thanks.
D
Don Guillette
The cunningham is use to adjust draft position. Review the article I wrote on the subjevt of draft depth and draft position. You would want to increase the twist or depower as the wind piped up. In effect you would be blowing air and power out of the top of the sail.
K
Karl Murphy
twist adjustment w/o traveler
My 240 does not come with a traveler. Just the main attached to the cocpit floor and the boom at the mid-boom position. I know that if I harden up on the vang, it will pull the boom down and straighten the twist, but there are times in light to medium air when to get the top tale tail to match the middle tail, I could add a bit more twist. W/o the traveler, now what? Easing the vang doesn't seem to help.
My 240 does not come with a traveler. Just the main attached to the cocpit floor and the boom at the mid-boom position. I know that if I harden up on the vang, it will pull the boom down and straighten the twist, but there are times in light to medium air when to get the top tale tail to match the middle tail, I could add a bit more twist. W/o the traveler, now what? Easing the vang doesn't seem to help.
J
John J
Since you say you have a vang, here is what we used to do. Take the vang and attach it to either a stancion or the jib lead track on the windward side. You can then use this to pull the boom back to the center position, while at the same time easing the main sheet to increase twist.
D
Don Guillette
Twist adjustment w/o traveler
Karl: The sail trim controls for twist in the mainsail are the BOOM VANG and the MAINSHEET. The main purpose of the TRAVELER is to adjust the angle of attack. In 1- 5 knots, the mainsail needs twist. I use a technique called "trimming to a point of draw". You merely ease the mainsheet until the luff ripples and then trim in until the ripples just stop. That takes care of the mainsheet. Now for the boom vang. In 1-2 knots you do not want any tension on the vang. In fact, you want to use your topping lift to lift up the boom slightly. In 2-5 knots, you would apply minimal tension and in 5-15 knots you would apply snug tension. Over 15 knots, you'd apply heavy tension. The problem is that there are numerous sail trim controls on a sailboat and the larger the boat, the more they are and they all have to work together. It's like adjusting the 4 barrels on a carburetor. You can't just adjust 2 and expect the car to run smoothly. Same thing with your sail trim controls but space on the forum does not permit an outline of every adjustment for every control for every wind condition and point of sail. I hate to give a commercial but I have a product that will help most sailors. I developed a Sail Trim Chart, which is sold by Sailboatowner.com, and which identifies all your sail controls and gives you the settings you need when sailing on various points of sail and wind conditions. In effect, I've taken the guess work out of mainsail and jib adjustments. Take a look at my Sail Trim Chart and see if it is anything that would work for you.
Karl: The sail trim controls for twist in the mainsail are the BOOM VANG and the MAINSHEET. The main purpose of the TRAVELER is to adjust the angle of attack. In 1- 5 knots, the mainsail needs twist. I use a technique called "trimming to a point of draw". You merely ease the mainsheet until the luff ripples and then trim in until the ripples just stop. That takes care of the mainsheet. Now for the boom vang. In 1-2 knots you do not want any tension on the vang. In fact, you want to use your topping lift to lift up the boom slightly. In 2-5 knots, you would apply minimal tension and in 5-15 knots you would apply snug tension. Over 15 knots, you'd apply heavy tension. The problem is that there are numerous sail trim controls on a sailboat and the larger the boat, the more they are and they all have to work together. It's like adjusting the 4 barrels on a carburetor. You can't just adjust 2 and expect the car to run smoothly. Same thing with your sail trim controls but space on the forum does not permit an outline of every adjustment for every control for every wind condition and point of sail. I hate to give a commercial but I have a product that will help most sailors. I developed a Sail Trim Chart, which is sold by Sailboatowner.com, and which identifies all your sail controls and gives you the settings you need when sailing on various points of sail and wind conditions. In effect, I've taken the guess work out of mainsail and jib adjustments. Take a look at my Sail Trim Chart and see if it is anything that would work for you.
E
Eric Steege
Sail Trim Chart is WONDERFUL
I bought this sail trim chart, and I am very impressed. While it is almost impossible to use while sailing (because our hands are busy, and there is a lot going on) review of it after each sail/race has helped me on the next trip out. It is relatively inexpensive, and I it will help you sort out all the things that are going on when trying to trim the sails.
I bought this sail trim chart, and I am very impressed. While it is almost impossible to use while sailing (because our hands are busy, and there is a lot going on) review of it after each sail/race has helped me on the next trip out. It is relatively inexpensive, and I it will help you sort out all the things that are going on when trying to trim the sails.
- Status
- Not open for further replies.