Educate me on the use of the sail's telltales

[Ripster]

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.

This is the book I bought when I changed from power to sail to learn what all this talk of trimming and rig tuning was all about - IMO its very good and easy to understand. Mind you applying the theory in practice can be challenging but, you will never be bored!

 

[grumpy_o_g]

As someone who sails on quite a few different boats and doesn't get to know any particular boat really, really well I've normally found tell-tales an excellent guide as to what the airflow is doing over the sails but that there isn't a hard and fast rule to convert that to boat speed. I've seen quite a few tell-tales planted where they are rarely if ever flying straight. Trying to get them all flying horizontally would be an excellent start though. I am definitely not one of life's racers and sailing against a broadly similar boat and trying things to see what works best is the only way I've ever been able to really tell if anything is making a a difference (unless it's really drastic).

 

[LittleSister]

While I have cars, they cannot be moved on the fly

On a modest sized boat, and if the wind is not too strong, I find I can move the cars rearward under load without too much problem. A bit more wind dependent, I can usually also move them forward if I can hold the genoa sheet down by standing on it just ahead of the car (to take the load off the car), then pull up the stop and pull it forward.

It is a bit of a faff, and my excuse for not having the sails set properly. (I'm still trying to think of an excuse for the main.) On the boat of my dreams I'll have towable genoa cars.

 

[Neil]

Maybe I should cut the telltales off, then I wouldn't have to worry........

 

[Javelin]

First thing is to decide if you're going to steer to the trim or trim to the course.

If you trim to the course then you'll be adjusting a fair amount if you want it perfect.
If you steer to the trim you'll need to sit where you can see the tell tails but it easier.
Looking from the windward side of the cockpit,
If the inside tell tail lifts then in theory you need to either sheet in a little or bear away.
If the outside tell tails lift then you need to ease sheets or head up.

Its far more important to keep the outside tell tail streaming than the inside one

However the issue is the rules change depending what boat you're sailing, the wind strength, direction of the wind and the sea state.
and you need to be looking at the right tell tails first.
Sailing upwind,
The top third of each sail does two thirds of the work !
That's a big one to get your head around.
The chances are the tell tails you are looking at are the bottom 2 sets which are the easiest to see.
The most important ones are the top set.

Following on from that, leech tell tails are more important to get right.

If you can give me some details on your boat I can then give you some baselines to work to.

Class
or
LOA
Keel type and draft
Rig type (masthead, fractional, sloop, ketch etc)
Approx weight.

 

[Neil]

First thing is to decide if you're going to steer to the trim or trim to the course.

If you trim to the course then you'll be adjusting a fair amount if you want it perfect.
If you steer to the trim you'll need to sit where you can see the tell tails but it easier.
Looking from the windward side of the cockpit,
If the inside tell tail lifts then in theory you need to either sheet in a little or bear away.
If the outside tell tails lift then you need to ease sheets or head up.

Its far more important to keep the outside tell tail streaming than the inside one

However the issue is the rules change depending what boat you're sailing, the wind strength, direction of the wind and the sea state.
and you need to be looking at the right tell tails first.
Sailing upwind,
The top third of each sail does two thirds of the work !
That's a big one to get your head around.
The chances are the tell tails you are looking at are the bottom 2 sets which are the easiest to see.
The most important ones are the top set.

Following on from that, leech tell tails are more important to get right.

If you can give me some details on your boat I can then give you some baselines to work to.

Class
or
LOA
Keel type and draft
Rig type (masthead, fractional, sloop, ketch etc)
Approx weight.

It's a Sadler 25, fin and skeg, 1.4m draught, mast head rig, 1,800kg. I need to learn how to trim the sails for the course to steer, though with the caveat that I'd expect to make minor steering corrections to the wind.

 

[greggron]

It's a Sadler 25, fin and skeg, 1.4m draught, mast head rig, 1,800kg. I need to learn how to trim the sails for the course to steer, though with the caveat that I'd expect to make minor steering corrections to the wind.

Congrats on a brilliant choice of boat. As owner of same it have learned that understanding how to optimise sail trim makes a huge difference, leaving many with larger boats scratching their heads as you overhaul them. Worth the investment of time to learn all about it.

 

[RobbieW]

On a modest sized boat, and if the wind is not too strong, I find I can move the cars rearward under load without too much problem. A bit more wind dependent, I can usually also move them forward if I can hold the genoa sheet down by standing on it just ahead of the car (to take the load off the car), then pull up the stop and pull it forward...

or put a rolling hitch around the sheet and secure it to a strong point. midships cleat for example, then adjust the car at your leisure and release.

Another thought, though contradicted by Javelin, is that on the wind the lower tell tales are the ones to watch and off the wind its the uppers. That may be consistent with Javelin's advice but a cruder method. It made sense to me as on the wind the top of the sail is more likely to be open and off the wind it gets closed - but that assumes the cars are moved to suit.

 

[Javelin]

Lovely boat, easily driven with very good manners.

First we need to set your track position for the jib.
You can get the tell tails to stream correctly even with the track in the wrong place so its important to set this up first.

To help with this you need a Leech tell tail 1/4 of the way down on your jib.
Ideally you would have three leech tell tails at 1/4, 1/2 and 3/4

Assuming it's a force 3 with flat water.
Mainsail boom set on center line.

The idea is to get these jib leech tails to go lazy.
They go lazy because you have slowed the airflow on the windward side of the jib.
If you slow the air too much you will stall the air flow and the leech tell tail will curl.
If they are all streaming then the airflow is too fast and you need to you need to sheet in.
If the top one is streaming and the bottom ones are either lazy or curl then you need to move the car forward a little.
If the top one is curling then you need to move the car aft.

So leech tell tails have three phases - Streaming, lazy and curl - Lazy is what you want.

OK your jib cars and sheet should now be set.
The jib tell tails now work as a steering aid.
You steer so that the windward tell tail just starts to lift.
The leeward tell tail should always stream - if it curls then you are pointing too low.
With a big jib on the sadler it is easy to let her drift off downwind.
As the wind builds the windward tell tail can be allowed to curl more often.
In a F3 with flat water your target will be 5.2 to 5.4 knts through the water.

You don't need tell tails on the main but you do need leech tell tails, usually on the batten pockets.
They work slightly differently on the main.
In 5 knt or less wind the top tell tail on the main needs to stream about 25% of the time.
In 5 to 10knts it should stream about 50%
Above that it should just stream.

To reduce streaming you need to add more mainsheet tension (less twist)
To increase streaming you need less mainsheet tension. (more twist)

The lower main leech tell tails report back on the general shape of your main sail.
When the top leech telltale streams steadily but the second one is curling, this tells you that your main is too full in the middle.

 

[Javelin]

Ooops just noticed that was all for upwind.

On a reach this change a bit.
As soon as you ease sheets you will allow the sails to twist.
So the jib cars need to go forward and the Kicker needs to be wound on as the mainsheet no longer pulls down on the leech.

When reaching the top tell tails are the ones to watch.
It is quite hard to get the upper and lower tell tails to agree so if I'm on a long reach I often move the sheet lead right out to the rail on a snatch block.

It's now a balance between reducing twist which gives you power and speed, against heeling and weather helm.
You want as little twist as you can handle but if you get too much healing or your arm is falling off from weather helm increase twist releasing power.

In winds above 15 knts the importance of tell tails and leech tell tails reduces.
Focus should then be on balance of the sails, heel and picking your way through the waves.

 

[LittleSister]

Thank you Javelin, that's very clear. I'm going to copy that, take it to the boat and practice.

If you see a little long-keeler surfing past Southwold, that'll be us armed with your advice, going so fast we've overshot the Orwell, Deben and Ore!

 

[Dipper]

Thank you Javelin, that's very clear. I'm going to copy that, take it to the boat and practice.

If you see a little long-keeler surfing past Southwold, that'll be us armed with your advice, going so fast we've overshot the Orwell, Deben and Ore!

+1. That looks really useful and I think it all fits in with what we learnt from Adam Bowers the other day. I'm also going to copy it. Thanks Javelin.

 

[Javelin]

The advice will change a little on each class of boat,
or at least the priorities will change.

The Sadler is light, pointy and responsive and the later ones were almost over powered.

From what I remember about the Samphire is that the long keel is not very deep so they tend to track ok in light winds but once you get much heel on they suffer from a fair bit of leeway.
The mainsheet feed is on the centre line on the one I remember and somewhat aft of the boom so getting the boom on or near the centerline was difficult.
If you don't get it on the centre or at the very least inside the qtr then with the jib sheeted in you run the risk of stalling the airflow a lot earlier in the slot between the jib and the main and probably backwind the mainsail.
The heel will also induce quite a lot of weather helm which you then have to fight slowing yourself down.
I might be wrong or it might ring some bells in which case there are a few things you can do to help.

With the bilge keel, you have the drag of the windward keel wanting to pull you head to wind.
You can't point as high as a fin keel anyway so you set the sails for maximum grunt instead of speed.
Flat sails = Speed
Full sails = grunt
Essentially on heavier boats you use slightly less jib sheet tension which gives you a more curved foot between the clew and tack but you need the car further forward to maintain the correct twist.
This gives you more power to punch through waves etc
The tell tails will still work in the same way.

 

[Neil]

Lovely boat, easily driven with very good manners.

First we need to set your track position for the jib.
You can get the tell tails to stream correctly even with the track in the wrong place so its important to set this up first.

To help with this you need a Leech tell tail 1/4 of the way down on your jib.
Ideally you would have three leech tell tails at 1/4, 1/2 and 3/4

Assuming it's a force 3 with flat water.
Mainsail boom set on center line.

The idea is to get these jib leech tails to go lazy.
They go lazy because you have slowed the airflow on the windward side of the jib.
If you slow the air too much you will stall the air flow and the leech tell tail will curl.
If they are all streaming then the airflow is too fast and you need to you need to sheet in.
If the top one is streaming and the bottom ones are either lazy or curl then you need to move the car forward a little.
If the top one is curling then you need to move the car aft.

So leech tell tails have three phases - Streaming, lazy and curl - Lazy is what you want.

OK your jib cars and sheet should now be set.
The jib tell tails now work as a steering aid.
You steer so that the windward tell tail just starts to lift.
The leeward tell tail should always stream - if it curls then you are pointing too low.
With a big jib on the sadler it is easy to let her drift off downwind.
As the wind builds the windward tell tail can be allowed to curl more often.
In a F3 with flat water your target will be 5.2 to 5.4 knts through the water.

You don't need tell tails on the main but you do need leech tell tails, usually on the batten pockets.
They work slightly differently on the main.
In 5 knt or less wind the top tell tail on the main needs to stream about 25% of the time.
In 5 to 10knts it should stream about 50%
Above that it should just stream.

To reduce streaming you need to add more mainsheet tension (less twist)
To increase streaming you need less mainsheet tension. (more twist)

The lower main leech tell tails report back on the general shape of your main sail.
When the top leech telltale streams steadily but the second one is curling, this tells you that your main is too full in the middle.

I think I'll have print this and keep it on the boat!

 

[LittleSister]

Javelin, that's enormously helpful. Thank you.

Our main disadvantage is a tired, baggy mainsail. Though it has successfully carried us thousands of miles in that state, I'm sure we'd get more speed, pointing ability and less heeling if Santa brought us a new one. In the meantime your tips will hopefully help us get the most out of what we have.

From what I remember about the Samphire is that the long keel is not very deep
Correct
so they tend to track ok in light winds but once you get much heel on they suffer from a fair bit of leeway.
True (but the shoal draft also enables us to cut corners others can't!)
The mainsheet feed is on the centre line on the one I remember and somewhat aft of the boom so getting the boom on or near the centerline was difficult.
That would not be standard. There is a main sheet track across coaming at the back of the cockpit, so there is a reasonable amount of control and the boom can be brought to, or beyond, the centreline no problem. As the mainsheet pulls down aft at an angle from the end of the boom, there is not full advantage in controlling twist, but probably enough power for the modest sail area.
If you don't get it on the centre or at the very least inside the qtr then with the jib sheeted in you run the risk of stalling the airflow a lot earlier in the slot between the jib and the main and probably backwind the mainsail.
The heel will also induce quite a lot of weather helm which you then have to fight slowing yourself down.
I might be wrong or it might ring some bells in which case there are a few things you can do to help.

With the bilge keel, you have the drag of the windward keel wanting to pull you head to wind.
You can't point as high as a fin keel anyway so you set the sails for maximum grunt instead of speed.
Flat sails = Speed
Full sails = grunt
Essentially on heavier boats you use slightly less jib sheet tension which gives you a more curved foot between the clew and tack but you need the car further forward to maintain the correct twist.
This gives you more power to punch through waves etc
The tell tails will still work in the same way.

 

[Neil]

The jib tell tails now work as a steering aid.
You steer so that the windward tell tail just starts to lift.
The leeward tell tail should always stream - if it curls then you are pointing too low.
With a big jib on the sadler it is easy to let her drift off downwind.
As the wind builds the windward tell tail can be allowed to curl more often.
.

but to turn this around:

The jib telltales now work as a sheeting aid.

You sheet in so that the windward tell tail just starts to lift.
The leeward tell tail should always stream - if it curls then you need to sheet in

or have I completely misunderstood?

 

[Javelin]

err, yes.

Say you are aiming for a buoy you set your sails accordingly.
When the wind shifts you adjust the sails.

1st Priority is always if the leeward tell tail curls - in which case you ease the sheet.

If the windward tell tail curls you should pull it in, however I usually use this windward curl as a warning that the sail may start to luff or backwind.
I'd then sheet in on the luff or sail backing.

The position of the tell tails aft from the luff makes a difference.
In mine they are only 6" back which makes them very twitchy.
In most cruiser sails they tend to be 14" or so aft of the luff, this makes them less sensitive.

So if using tell tails that are 14" or so aft of the luff, if the windward tail curls its probably time to sheet in.

Not sue if I explained this very well,

Summarise,

Leeward tell tail curls = Sheet out
Windward tell tail curls = Sheet in

After adjustment check top leech tell tail,
If sheeted out then usually the car will need to be eased forward

 

[Neil]

Thanks, now I seem to getting a (small) handle on it. It's the idea encapsulated in your first sentence that got me started on this: "Say you are aiming for a buoy you set your sails accordingly".

It's the use of the telltales to set the sails accordingly, that I needed to grasp. I feel I can now experiment with the "Leeward tell tail curls = Sheet out , Windward tell tail curls = Sheet in" concept.

During wind shifts, I would generally feel through the boat whether I should harden up or bear away a bit, but now I'll look at the telltales too, once I've been able to set the sails accordingly

 

[Javelin]

Just to add a little extra.

Ok so you're heading for that mark, sails trimmed nicely.
You are on starboard tack and you see a gust coming, if you are in the Northern Hemisphere the chances are it will be a header, so be ready to ease sheets or bear off.
If you are on Port tack the opposite is true.
Not 100% accurate but I've made a good few places in races knowing that.

Around the UK we tend to get oscillating shifts which occur on a regular-ish basis, like every 30 seconds 5 deg one way, 40 seconds later 10 the other and so on.
With these types of shift its easier and quicker just to steer to the trim, ie head up or bear off, as the average will be still towards the buoy.
However when you find the Average is no longer towards the mark its the time to adjust the sheets.

 

[LadyInBed]

On my new genoa, I have put 2nd and 3rd sets of teltails further back down the sail so I have something to go by when reefed.
How should the extra sets behave when beating with the genoa fully diploid?
afterthought: or don't they have any bearing on the situation!