Telltales on the jib leech don’t seem to be popular. Arvel Gentry (Americas Cup) uses his three in a row luff steering telltales and some near the leech but not on it. But mostly you don’t see any on or near the leech. Why is this?
Jib Telltales
- Thread starter Quoddy
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I've used tell tales on my jib (and genoas) for years. One exactly half way between the head and the tack and one half way between the center tale and either the tack and the head for the other two tell tales. If possible I like to have the lowest (and normally the easiest to see from the helm) tell tale on a circular clear window so that I can see both sides.
All three tell tales should be about a foot or so back from the luff so that it gets clean air without turbulence. Most sailmakers can tell you the optimum distance back from the luff.
When heading into the wind all three tell tales should "jump" up at the same time. If not you need to adjust the block for the clew either forward or back. When all three jump together your sail is properly set for those wind conditions.
If the inside tell tale jumps up, you are pinching into the wind. If the outside tell tale jumps up you are too far off the wind. Either adjust the sail or the angle of the boat.
I also use red and green wool for the tell tales, although many people like magnetic tape. The tell tales should be about six inches long with the window an inch bigger so that the tell tale does not hang up on the stitching..
I've used tell tales on the leech of the sail but have not found them as useful as those on the luff.
I've also have used tell tales on my jibs that are roller furled and have never had a problem with them. But tell tales on the leech of the roller furling main have either jammed or been torn off of the sail. If any one can advise on tell tails on the main I'd like to know.
All three tell tales should be about a foot or so back from the luff so that it gets clean air without turbulence. Most sailmakers can tell you the optimum distance back from the luff.
When heading into the wind all three tell tales should "jump" up at the same time. If not you need to adjust the block for the clew either forward or back. When all three jump together your sail is properly set for those wind conditions.
If the inside tell tale jumps up, you are pinching into the wind. If the outside tell tale jumps up you are too far off the wind. Either adjust the sail or the angle of the boat.
I also use red and green wool for the tell tales, although many people like magnetic tape. The tell tales should be about six inches long with the window an inch bigger so that the tell tale does not hang up on the stitching..
I've used tell tales on the leech of the sail but have not found them as useful as those on the luff.
I've also have used tell tales on my jibs that are roller furled and have never had a problem with them. But tell tales on the leech of the roller furling main have either jammed or been torn off of the sail. If any one can advise on tell tails on the main I'd like to know.
Those sailor without leech tell tales apparently never read a 'how to sail' book written based upon sound or 'valid' aerodynamic principals; but, rather were based on myths, guesses, and 'magic', etc.
Even what one learns in US public high school 'science' classes about how wings 'work' is absolutely WRONG, & even the Wright Brothers knew this.
You can start here: http://shop.sailboatowners.com/prod.php?51998/Sail+Trim+Users+Guide then also join the 'sail trim' discussions at http://forums.sbo.sailboatowners.com/forumdisplay.php?f=17
.... and when you master Don Guilette's simply elegant 'how to' book, then you can work your way up to the 'exact aerodynamic methods' such as found at: www.arvelgentry.com --- probably ALL the foremost sailors of the world did at one time or another.
Even what one learns in US public high school 'science' classes about how wings 'work' is absolutely WRONG, & even the Wright Brothers knew this.
You can start here: http://shop.sailboatowners.com/prod.php?51998/Sail+Trim+Users+Guide then also join the 'sail trim' discussions at http://forums.sbo.sailboatowners.com/forumdisplay.php?f=17
.... and when you master Don Guilette's simply elegant 'how to' book, then you can work your way up to the 'exact aerodynamic methods' such as found at: www.arvelgentry.com --- probably ALL the foremost sailors of the world did at one time or another.
My take on why you don't see too many folks using jib leech telltales is this: Sailmakers never put them on new sails, so no one knows any better. I never did and like you Quoddy, I've seen very few boats use them.
There is a ton of information and instruction on how to set up and use the jib luff telltales... for steering and trimming... but there is very little about using jib leech telltales.. how to read them and how to adjust, unless, of course you plow through the Arvel Gentry stuff, is pretty dense unless you're an engineer (sorry Rich). When you purchase a package of telltales... the instructions don't say anything about putting them on the leech.
I've had quite a few sailing classes and never heard the instructor give any emphasis to jib leech telltales...
That said... I'm going to put them on my headsails and see if it improves my trim technique.
I know that it will help me see airflow attachment but what is the correct action to take if they're not flowing properly.
I would certainly appreciate hearing how some of you advanced sailiors use their jib leech telltales.
There is a ton of information and instruction on how to set up and use the jib luff telltales... for steering and trimming... but there is very little about using jib leech telltales.. how to read them and how to adjust, unless, of course you plow through the Arvel Gentry stuff, is pretty dense unless you're an engineer (sorry Rich). When you purchase a package of telltales... the instructions don't say anything about putting them on the leech.
I've had quite a few sailing classes and never heard the instructor give any emphasis to jib leech telltales...
That said... I'm going to put them on my headsails and see if it improves my trim technique.
I know that it will help me see airflow attachment but what is the correct action to take if they're not flowing properly.
I would certainly appreciate hearing how some of you advanced sailiors use their jib leech telltales.
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Leech tell tales are very simple: If the leech tell tales are not flowing straight back parallel to the sail, the sails efficiency is greatly decreased (and is overtrimmed or undertrimmed).
Aerodynamic efficiency is PRIMARILY due to what is known at the "Kutta Condition" or the air flow on both sides of the leech being at equal speed and equal amount .... without this important condition being met, you dont have full aerodynamic flow across the whole sail. If you dont have leech tell tales youll never be able to SEE to adjust so that the airstreams are equal on both sides of the leech.)
Aerodynamic efficiency is PRIMARILY due to what is known at the "Kutta Condition" or the air flow on both sides of the leech being at equal speed and equal amount .... without this important condition being met, you dont have full aerodynamic flow across the whole sail. If you dont have leech tell tales youll never be able to SEE to adjust so that the airstreams are equal on both sides of the leech.)
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