Educate me on the use of the sail's telltales

[Neil]

Since I've got new sails, and no excuse not to trim them properly, I need to learn to use these things. The genoa, for example, has them both sides - I'm guessing I need to watch the ones on the inside? - and they need to stream straight backwards? A first observation is that I need to sheet it in quite tight, even on a broad reach to achieve this, whereas my inclination would be to ease the sheet on a broad reach?

 

[mjcoon]

Since I've got new sails, and no excuse not to trim them properly, I need to learn to use these things. The genoa, for example, has them both sides - I'm guessing I need to watch the ones on the inside? - and they need to stream straight backwards? A first observation is that I need to sheet it in quite tight, even on a broad reach to achieve this, whereas my inclination would be to ease the sheet on a broad reach?

You need to watch the tell-tales both sides, I'm afraid. A good excuse to sail only in bright sunshine so you can see the shadow through the sail! And ideally both should be streaming equally, and I'm sure you will have to ease the sail on a broad reach to achieve this, as you say.

Also I hope you have tell-tales at different heights, and to keep them all streaming you may have to adjust the genoa sheet cars to get a consistent angle all the way up the luff.

Have fun tweaking! Mike.

 

[Nostrodamus]

Neil it is actually a really good question. How long have you got!

 

[Rigger Mortice]

I've found this book pretty good. It covers tuning the standing rigging very thoroughly too. http://fernhurstbooks.com/product/sail-rig-tuning/

They also do another book which is dedicated to tweaking the jib, but I've not read that.

 

[Bav34]

If you're on a beat and the inside (windward) ones are lifting, bear away. If the outside ones are lifting/droopy head up.

If you're on a reach and you get the same effects sheet in or sheet out.

It's all to do with maximising the flow of wind across the sail.

 

[wiggy]

When I used to teach sailing I would tell my students to move the tiller towards the side with the flapping telltale if sailing upwind.

 

[johnalison]

I don't use my jib's tell-tales much, at least when close-hauled. On a reach they can be useful to determine how far forward to move the sheet car, ideally so that the leading strips "break" at the same time.

The ones one the leach of the main are more useful and I try to adjust so that they all stream. This may involve easing the kicker a bit since sail shape alone doesn't give a full indication.

 

[chewi]

If you're on a beat and the inside (windward) ones are lifting, bear away. If the outside ones are lifting/droopy head up.

If you're on a reach and you get the same effects sheet in or sheet out.

It's all to do with maximising the flow of wind across the sail.

sailing to windward...

"Tiller to spiller"

ie helm up if the windward one lifts, and vice-versa.

 

[Bav34]

I have a wheel

 

[chewi]

as to how they work...
Arvel Gentry had a website with his works as a Boeing fluid dynamicist and Americas cup consultant that are very readable and authoritative, but the original site has been allowed to drop.
They have been rescued here http://arvelgentry.jimdo.com/articles/

The gist of it is that for the sail to perform the airflow has to be attached to the sail.
If the angle of attack becomes too much the flow will detach behind the leading edge, but then reattach until the angle is exceeded to far, then it will stall.
the leading edge telltails act as an early warning to that stall.

If one lifts before another , the sail is twisted, so the car can be adjusted until they all lift in sympathy.





.

 

[Dipper]

Since I've got new sails, and no excuse not to trim them properly, I need to learn to use these things. The genoa, for example, has them both sides - I'm guessing I need to watch the ones on the inside? - and they need to stream straight backwards? A first observation is that I need to sheet it in quite tight, even on a broad reach to achieve this, whereas my inclination would be to ease the sheet on a broad reach?

We've just had an illuminating talk at our club from Adam Bowers who trains sailors up to world championship level. Unfortunately, I too thought that all the tell tales should be streaming level all the time but that isn't necessarily the case. He has an interesting concept about the fourth corner which in simple terms is that part of the leech about three quarters of the way up the sail. This is the part of the sail that I thought was of little importance but it is absolutely crucial to get this trimmed correctly depending on the weather conditions and the boat. Sometimes you will need to spill wind from this point, other times you need to harness all the wind you can. Controlling the fourth corner automatically trims the rest of the sail.

Adam also came out on our boats and I found that quite a bit of the time I had my sails trimmed inefficiently despite having raced in the club for many years. I really can't summarise what he taught us but if you get the chance to hear him, go for it.

I now need to get back out on the water and try to remember what he taught us.

 

[KREW2]

Adam Bowers....... For those of you who have not heard of him, is an international coach.

A few weeks ago he did a presentation at our club, followed by three on the water sessions. His style of teaching, as well as being entertaining, and informative, is done with a lot of enthusiasm.
Last Saturday was dedicated to cruisers. Only 4 cruisers turned up for the four hour on the water session, during which he had us sailing a sausage course involving a beat and a downwind run.
He followed in his rib, shouting advice, and videoing the set of the sails. My genoa car went to places it had never been before.
He then boarded each boat and spent about 40 minutes on each. We were beating back in about 15 knots of apparent wind, with a bit of weather helm, to my mind not too much to worry about, to Adam it was a sin. After much moving of the cars, main sheet traveller, and adjusting tension on both sheets he had the boat sailing by itself.
He is a great believer in watching the telltales, so much so he also likes to have them on the luff of the main. I only took in a fraction of what he was telling us, and as has been mentioned there is far to much info to post on here, so best get a book. The debrief after was just as good, and seeing the videos was an eye opener.
It is also worth reading Adam's theory of the fourth corner on the sail, get it right and it works.
All in all one of the best days on the water I have had for a long time.

 

[KREW2]

Bloomin Hek Dipper, I didn't realise it took me half an hour to write that.

 

[Neil]

Gosh. So I'm not likely to have it sorted next outing then..........

Well, every day is an opportunity to learn something new

 

[Dipper]

Gosh. So I'm not likely to have it sorted next outing then..........

Well, every day is an opportunity to learn something new

Getting them all streaming horizontally would be a reasonable compromise. That's what I did for years.

 

[greggron]

General rule: down and out, up and in...

 

[mrming]

As well as following the advice offered here, you could do worse than buy a book on sail trim - as others have said, there's a lot of different factors at play, principally around controlling the amount of twist in each sail. The principles are pretty straightforward, but a few diagrams go a long way to helping you understand it all.

 

[Neil]

I've looked at a few Youtube videos on sail trim. Several talked of moving the genoa cars to get the telltales flying straight. While I have cars, they cannot be moved on the fly - I think their adjustment is for different jibs (rather than my furler); set the position for each sail and then that's it. Leach lines? don't have'em.

My only real control is the sheet. Can I get the required control just by sheeting in or letting a bit out?

 

[mrming]

The trick is to move the car on the windward side before you tack. You can try out the new position on the next tack and then (if it's an improvement) move the other one to match.

Car back opens the top of the leech (twist), car forward closes it down.

 

[Dipper]

I've looked at a few Youtube videos on sail trim. Several talked of moving the genoa cars to get the telltales flying straight. While I have cars, they cannot be moved on the fly - I think their adjustment is for different jibs (rather than my furler); set the position for each sail and then that's it. Leach lines? don't have'em.

My only real control is the sheet. Can I get the required control just by sheeting in or letting a bit out?

Ideally you will need to move the cars depending on wind strength and point of sail. Can you adjust the leeward one then tack/gybe, adjust the other one and tack/gybe back again? I know when I was sailing downwind, my cars were set way too far aft. I suppose you could set them for beating to windward in a moderate breeze and accept that other wind strengths and points of sail would be a compromise.