It was not clear at all why telltales in near center of mainsail were helpful. How are they helpful?
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Frank: Normally, the mainsail comes with a minimum of 3 telltales on the leech of the sail. With those telltales your reading the "exhaust" off the sail. That is nice and helpful but what you really want to read is the "entry" flow just as you do with the telltales on the jib. You want the leading edge of the sail to split the wind right down the middle. Part of the problem with air flow over the mainsail is that a portion of the flow is blocked by the mast, which is all the more reason to have them. The whole idea of telltales is to read the ATTACHED FLOW of air on the sail. You want the wind attached to both sides of the sail and you have no way of knowing if it is (or not) without telltales. Without telltales I can't really tell and I know exactly what I'm looking for. I hate sailing on boats without teltales. It just makes the sail trim job more difficult and you end up guessing about sail trim adjustment. You read the 2 center middle mainsail telltales the same way you read the jib telltales and make your sail trim adjustments the same way depending on what they are telling you. Reading telltales is an art and I devote about 7 pages to it in my book the Sail Trim Users Guide. When it is explained in simple English, you'll be amazed at how easy (and helpful) it is to understand. Lets say I only had 3 mainsail telltales to attach (the store ran out of them or something). The way I would utilize the 3 I had would be to put one at the top batten - to read twist - and I'd put the other 2 in the middle of the sail. That is how I read them anyway even when I have a full set attached. I glance at the middle and bottom batten ones but not much. Does anyone have any questions about reading telltales? Here's a few questions you should be able to easily answer. On the jib, which telltale is the steering telltale? What trim adjustment do you make if either the inside or outside telltale flips? If you can't immediately answer either of those question - buy my book!!!
Assuming the windward telltale in the center of the main sail were lifting, would you apply more tension to the main sheet or bring the traveller to windward?
ED: Here's a quick tip for both the jib and main. If the inside jib telltail lifts - sheet IN. If the outside telltail lifts - ease the sheet OUT. I have to use simple stuff so I don't get confused!! The same principle (almost) applies to the main except I'd use the traveler first in place of the mainsheet. The thing about all this is that we are presupposing that all the sail trim controls are set correctly for the wind conditions and point of sail. The next question is how do you know if your settings are correct? Easy as I've developed a sail trim chart that will give you the correct sail trim setting for every sail trim control on the main and jib for every wind condition and point of sail. It is available through the ships store on this site. The beauty of the chart is after you use it a number of times you won't need it anymore because you'll know the settings to use for each point of sail and wind condition. My Sail Trim Chart "takes the guess work out of jib and mainsail adjustment".
Sail Trim
Don: Problem on a Hunter 306 with no backstay and a 110% Genoa: Beam reach, Main leech - all telltales streaming straight aft, Jib telltales all streaming traight aft, but Jib is significantly backwinding main (Forward 50 % of main). How do we cure this?
Don: Problem on a Hunter 306 with no backstay and a 110% Genoa: Beam reach, Main leech - all telltales streaming straight aft, Jib telltales all streaming traight aft, but Jib is significantly backwinding main (Forward 50 % of main). How do we cure this?
Wjssr: On a fractional rig, the engine is the main. On a masthead rig, the engine is the jib. So, what you should do is ease the jib sheet. Let it out JUST ENOUGH to stop the backwinding of the main. With a 110, it is not generating enough power to be benificial anyway. In fact, it is acting to the determent of the main. Trim the main for maximum power and then mess with the jib but don't let it disturb the main. Now if it was a masthead rig, my advise would be different. The jib is the first sail trimmed. Trim it for maximum power and then deal with the main. A lot of guys don't mind the backwinding bubble in the main but it is unnecessary. The air flow wants a smooth surface. Can you see a pilot flying a plane with a bubble on his wing? If sails were mounted horizontally on a boat it would be an airplane.
Location of mainsail tell tales
I would like to know the approximate location to place the main tell tales in their relation to the mast, which creates a lot of exhaust onto the luff area of the main.
I would like to know the approximate location to place the main tell tales in their relation to the mast, which creates a lot of exhaust onto the luff area of the main.
Foamy: The mast does not create as much exhaust as you might think. If it did it would make the mainsail totally ineffective, which we all know it is not. Anyway, the center mainsail telltales are place about in the center of the sail.
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