traveller adjustment???

[mickshep]

Morning forumites. My 1958 Van de Stadt was built for off-shore racing and had a number of bits and pieces for 'tweeking' the rig (Though nothing like the reams of spaghetti that addorns modern boats).
The main sheet attaches to the boom about 1/3 of the distance from the outboard end and is attached to a car that slides across the cockpit on a track. The position of the car is not fixed and I am re-fitting the tackles that allow the car to be adjusted.
Whilst it is pretty self evident that bringing the car amidships whilst hard on the wind will allow a tighter sheeting angle and an improvement in pointing ability I am wondering what other benefits can be had with the system. ie, Would inducing a twist in the sail be of benefit and if so under what conditions?
Sorry if this may seem a little vague but none of my previous boats have had a system like this though most modern boats appear to have a similar system fitted as standard. (Yes, built in 1958 makes Fosca my most modern boat to date) /forums/images/icons/blush.gif Cheers, Mike.

<hr width=100% size=1>My Mum say's I'm not a fat b@st@rd, just heavy boned.

 

[extravert]

The traveller controls the amount of twist in the sail when sailing from close hauled to a close reach. When sailing deeper than a close reach, the traveller loses its effectiveness, and you then use the kicking strap. The kicking strap can also be used to control sail twist when close hauled on a small boat, but on bigger ones you won't be able to get enough welly on the kicker, so use the traveller instead. (My current boat hasn't got a kicker at all, it's all done with the traveller, but sailing deeper than a reach never really happens, so it's not needed.)

Amount of twist in the sail is different from fullness in the sail. You can have a flat sail with twist, and a full sail without twist. So first you need the correct fullness for the wind conditions, ie. fuller with light winds, flatter with stronger winds. Fullness is set by halyard, cunningham and clew outhaul. (They are not entirely independent, reducing twist does also flatten somewhat as well).

The twist you need goes like this...

light winds - twist required. This is because in light winds you have more wind shear (change in true wind strength as you rise up the mast). Change in true wind strength gives a change in apparent wind angle as you go up. Therefore you need twist in order to keep the sail's angle of attack at the right angle. You can use the leach tell-tails for determining this, all flying continuously, apart from the top one, which should be flying 50%.

medium winds - less twist required. Wind shear much reduced, therefore more constant angle of attack of sail up the mast is required

high winds - a racing trick is to introduce twist again. When racing round the cans, you don't have time to reef/unreef on every change of direction, but you want appropriate sail area on the reaches/downwind legs. This will often mean too much sail area on the upwinds. Introducing twist again allows the top of the sail to fall away so that it is not drawing. It's a bit like a temporary reef. The top of course is contributing most to heeling, so it can have a significant effect if you haven't got enough biffas sitting on your rail. However, if not racing round cans, it's better to reef than do this.

<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.

 

[Hardley]

Very roughly, the idea is to pull traveller to windward in very light airs and let it off the leeward in strong winds.

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[Hardley]

Very roughly, the idea is to pull traveller to windward in very light airs and let it off to leeward in strong winds. Stops a lot of laying over in strong winds.

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[Hardley]

Very roughly, the idea is to pull traveller to windward in very light airs and let it off to leeward in strong winds. Stops a lot of laying over in strong winds.

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[Hardley]

Very roughly, the idea is to pull traveller to windward in very light airs and let it off to leeward in strong winds. Stops a lot of laying over in strong winds.

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[rwoofer]

Upwind, the mainsheet takes over from the kicking strap in terms of pulling the boom down to adjust twist and the traveller takes over from the mainsheet in terms of adjusting the angle of attack.

On my previous boat, a Hunter 707, I used to set the twist with the mainsheet and use the traveller to play the main in the lulls and gusts in order to keep the boat balanced.

RB

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[ex-Gladys]

Sorry,

the traveller does not induce twist in the main. Mainsheet and backstay can induce twist. You really need leech tell tales to make a traveller work, and you need to work it in conjunction with thee mainsheet. With the traveller centred and main hard in in a reasonable breeze, you probably won't have the leech tell tales flying (you need one at the top roughly 3-4 feet down the leech , and others about 4' intervals. 3 should be enough). You need to induce enough twist by easing the mainsheet so that all three tell tales stream. If they're not streaming, the leech is hooked. Then play around with the traveller until the main and jib are working together.

<hr width=100% size=1>Larry Botheras

Anderson 26 "Amber"

 

[mickshep]

Thanks everyone. will fit some tell tales over the w/end and have a play. I have used the outhall and halliard tension to alter the sail's fullness to suit conditions on all my former boats, it was the idea of induced twist that caught my attention and the effect it would have on progress, Thanks again. Mick.

<hr width=100% size=1>My Mum say's I'm not a fat b@st@rd, just heavy boned.

 

[extravert]

If someone has been using just their mainsheet and always left their traveller centred, then comes along and asks what benefit they can gain by using their traveller, I think it is a fair response to say that they can control their sail twist.

As the mainsheet and traveller are not independent adjusters when it comes to boom position and twist, I think it is a bit of a moot point as to which one affects which.

Even the sailmakers cannot decide...

Quantum

In conjunction with the mainsheet tension, the traveller effects both boom position and leech twist.

North Sails

MAINSHEET - used to control the twist.


<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.