Where are they best positioned and what are we looking to do to get the best results with their aid?

Hi Scotty. That's too big a subject to answer in a forum post. I'll try to take some pictures this weekend, weather permitting, and then put up an article next week! Have a good weekend

Cathy

As important are leech tell-tales on the main, they tell you whether you are oversheeted, have enough/too much twist etc.

If you want guidance on positioning of tell-tales, how to interprit etc, the best source of info is the North Sails web-site, there's a huge amount of great stuff there!

The Kemp web-site also has some good advice including setting up the rigging to help get the best from the sails.

Actually despite peoples thgoughts that its complicated - it's not.

Jib / Genny : At three levels ... approx. heights from foot, 25%   50%   75% ..... on average 30ft genny about 12 - 15" in from luff edge. That's single teltale each side of sail. I have 2 teltales each side of sail - but that's my "quirk" ... first as here stated, second set at 50% chord of sail at that level.

Mainsail only needs one teltale and that can be any side you wish as it will stream aft of the leech. It is positioned at about 25 - 30% downb from head ... often at second batten. The atachment as said is actually just in from leech so that woolie streams behind the sail.

OK - what they should do ... (they are really a tool for pointing , or sailing into wind not broad or downwind ...)

Genny ......... if both sides are streaming nicely along the sail = fine.  If windward one is curling back / not streaming then "bear of wind or sheet genny" in till it does. If Leeward is curling back or not streaming then "luff up or ease genny sheet" till it does. You should aim for the woolies to stream together both sides.

OK now to sheet lead position :

If windward woolie at top is streaming but not the bottom one - move sheet car aft. And vice versa if bootom one is streaming etc.

Main is simple that it needs to stream off sail nicely.  

In practice you will find you will have to compromise to arrive at best combination. Bearing / luffing will be the choice if wind strength dictates .. etc.

Good luck !!