Now check the mainsail
Now lets look at the mainsail. Over 50% of all the sails we clean and recondition at our plant and loft are mainsails, yet fewer than 20% have telltales in place. Telltales properly installed on the main can tell you a lot about the relationship between the headsail and main and the "slot" between them.
Telltales should be positioned on the leech at each batten; usually it takes 4. In the center of the main a little forward of center you will place a pair much in the same way you attached the ones one the jib. Put them between the first and second battens and between the second and third battens, again avoiding seams. (Refer to diagram).
While going to windward with both sails properly trimmed, keep your eye on the leeward telltales on the main. When you have them settled down, lying flat and streaming aft, look at the windward telltales.
At first you will find it difficult to have both sides streaming aft. First try flattening the main. If the bottom pair looks good but not the top, you are close. Ease the traveler and tighten the mainsheet. This should firm up the leech and give you the desired look. Don't get discouraged, a little practice will do wonders.
Then look at the leech
Now let's look at the leech. Exhaust or airflow as it leaves the main should have all telltales streaming aft. This will help to confirm your leech tension setting. Now move the traveler to windward. The telltales should start breaking at the top and work down. If it starts at the bottom first, add more leech tension. Make these adjustments as little at a time. It's more an exercise in finesse than brute strength.
As you bear off and ease your sails out, use the leeward telltales on the jib and the leech telltales on the main to trim well past a beam reach. As you have trimmed in, so will you let out. A little practice will make it second nature, But don't get easily satisfied or complacent! When all looks well I usually ease the sheets a bit and glance at the knot meter. Here we go again.
Don't forget the rig
Now we've covered the sails - how about the rig? Although you don't see it a lot, a lone telltale placed just above your head on the backstay can be a lot of help as you start down wind. Make sure its not in a position to foul or hand up. So goes the telltale, so goes the boom. Use the telltales position to square the boom and mainsail to the wind. If your telltale on the backstay is flying forward to port then the boom and mainsail should also be on the port side, square to the wind.
One last bit of info: If you like flying a spinnaker, you may find that trimming the pole and chute is much easier if you have a telltale attached to the bridle at the center of the pole. This helps to square the pole to the wind, then trim the chute.
