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Self-tacking jib track. Dyneema?

Joined
6 May 2020
Messages
1,324
Been reading up on self-tacking jibs. I see no point in the hugely expensive curved tracks with Torlon bearing cars, which basically do nothing except stop at both ends and what they do in the middle is irrelevant. Then they clack about on a run making a lot of noise.

What's to stop having a track made of a length of Dyneema, tension choosable, with a block running on it carrying another block with the sheet on it? With snapshackles it could be removable so my clumsy feet wouldn't trip over it in port. Surely the tension comes out of the system when the leech goes slack on either side so there'd be no reason for it not to tack to the other side?
 

Egbod

Member
Joined
7 Apr 2004
Messages
217
Location
Essex
Hi, when I sailed a Timpenny 22 with a self tracking jib the fitted metal track wasn't used and there was a length of wire, fairly taught between 2 brackets. The system worked very well. The "traveller " had the sheet lead forward to a block near the forestay fitting. Dyneema should work well.
I had control lines from both sides of the traveller so that I could heave too and to stop the sail flopping around downwind.
To save space and to work better , when I had a new jib made the clew used a pulley the same as the ones used on the clew of in mast reefing mainsails.
 

anoccasionalyachtsman

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Joined
15 Jun 2015
Messages
2,733
I'm under an NDA having been a bit involved in s/t development, so it's good to see a free thinker expose yacht building for the scam that it is. Of course a piece of string will do the job just as well. Put up a video when you've got it working and let the world see that the only point of the tracks and cars is to get more money out of your pocket.
 

wallacebob

Member
Joined
28 Dec 2008
Messages
108
Location
Embra, maybe onboard Matilda
Hunter Liberty’s (cat ketch) have a rail to allow main sheet Block to traverse the coach roof. Many owners have changed to simple and less noisy triangulated system: twin pulleys on boom, one each side of coachroof. This helps create better sail shape and bends mast, but also reduces oversheeting. As with self tacking systems the main sheet goes forward to a block, then back along the boom, then down/across/up/down/up. Pictures are in my head!
I have wondered if similar would work on a Jib foresail, but maybe more possible tangles of sheets.
 

Iliade

Well-known member
Joined
27 Apr 2005
Messages
1,598
Location
Shoreham - up the river without a paddle.
I have a curved track and car which is well lubricated but due to the rope friction in the pulley system I have to go forward and kick it following most tacks...

A boom with kicking strap would work far better for that sail, but get in the way when I rig the larger staysails.
 

lw395

Well-known member
Joined
16 May 2007
Messages
42,083
A significant number of dinghies have self tacking jibs.
Some International canoes have jib booms.
Most others have curved tracks.
I imagine if a simple piece of string did the job as well, dinghy builders would go for that?

Anyone who's sailed a dinghy with a rope traveller will be aware of the issues in making it sheet to the same place every time, particularly in lighter conditions.
A self tacker that can't be trusted to do its job right every time would be a great annoyance.
A curved track is not that expensive. A pair of normal jib tracks is not cheap either.

If you can make a rope s/t system work to your satisfaction then well done, but many have tried with 'mixed results'.
 
Joined
6 May 2020
Messages
1,324
Hunter Liberty’s (cat ketch) have a rail to allow main sheet Block to traverse the coach roof. Many owners have changed to simple and less noisy triangulated system: twin pulleys on boom, one each side of coachroof. This helps create better sail shape and bends mast, but also reduces oversheeting. As with self tacking systems the main sheet goes forward to a block, then back along the boom, then down/across/up/down/up. Pictures are in my head!
I have wondered if similar would work on a Jib foresail, but maybe more possible tangles of sheets.
Thanks, yes. I did consider something along those lines as it was the method used on my Lysander 17's mainsheet about 50 years ago. A look at Harken's page on the subject shows it as one way of rigging it on a self-tacking jib.

Self-Tacking Jibs: Why, How, and What to Watch Out For
 
Joined
6 May 2020
Messages
1,324
A significant number of dinghies have self tacking jibs.
Some International canoes have jib booms.
Most others have curved tracks.
I imagine if a simple piece of string did the job as well, dinghy builders would go for that?

Anyone who's sailed a dinghy with a rope traveller will be aware of the issues in making it sheet to the same place every time, particularly in lighter conditions.
A self tacker that can't be trusted to do its job right every time would be a great annoyance.
A curved track is not that expensive. A pair of normal jib tracks is not cheap either.

If you can make a rope s/t system work to your satisfaction then well done, but many have tried with 'mixed results'.
Thanks, useful. Adding a boom to the mix is one of the things I've been thinking about in order to get outhaul tension but of course it all adds to the cost and complexity. At the moment I'm still working on ideas because I can't afford to do it yet anyway! All ideas gratefully received.
 
Joined
6 May 2020
Messages
1,324
I have a curved track and car which is well lubricated but due to the rope friction in the pulley system I have to go forward and kick it following most tacks...

A boom with kicking strap would work far better for that sail, but get in the way when I rig the larger staysails.
I've been toying with the idea of a boom but getting a useful angle on the kicking strap could be a challenge. The whole lot would probably get in the way of using the chain locker too!
 

TLouth7

Active member
Joined
24 Sep 2016
Messages
478
Location
Edinburgh
The basic problem with this approach is that the sail will prefer to have a deeper belly with the block not all the way to the end of the 'track'. This problem gets worse as you increase sheet tension, but is improved by increasing 'track' tension. The easy solution is to use a jib boom, at which point you don't even need a 'track', though you do need an outhaul and kicker.
 

knuterikt

Active member
Joined
11 Sep 2006
Messages
1,624
Location
Oslo, Norway
I have a curved track and car which is well lubricated but due to the rope friction in the pulley system I have to go forward and kick it following most tacks...

A boom with kicking strap would work far better for that sail, but get in the way when I rig the larger staysails.
also have a curved track, but I cant understand where you have rope friction the prevents the car from moving. For optimal operation the distance from head stay to track should be some mm shorter in the middle of the track than at the ends. That way sheet tension is automatically slackened during the tack.
 
Joined
6 May 2020
Messages
1,324
The basic problem with this approach is that the sail will prefer to have a deeper belly with the block not all the way to the end of the 'track'. This problem gets worse as you increase sheet tension, but is improved by increasing 'track' tension. The easy solution is to use a jib boom, at which point you don't even need a 'track', though you do need an outhaul and kicker.
Interesting. Why would the sail prefer not to go all the way to the end on a rope track as opposed to a rigid track? Is it because the rope track would inevitably deflect upwards a bit no matter how much it was tensioned and the sail would refuse to go further out on the "downhill" bit of the rope since it would then be trying to go tighter? An alternative would be a rigid "track" such as a length of thick walled stainless tube with a dyneema soft shackle to connect the lower block, which would still be a lot cheaper than some of the fancy aluminium tracks and cars I've seen advertised.

Also not sure how the presence of a boom would remove the need for the track and still be self tacking, except possibly if it was rigged as Wallacebob suggested at #4?
 

anoccasionalyachtsman

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Joined
15 Jun 2015
Messages
2,733
Interesting. Why would the sail prefer not to go all the way to the end on a rope track as opposed to a rigid track? Is it because the rope track would inevitably deflect upwards a bit no matter how much it was tensioned and the sail would refuse to go further out on the "downhill" bit of the rope since it would then be trying to go tighter? An alternative would be a rigid "track" such as a length of thick walled stainless tube with a dyneema soft shackle to connect the lower block, which would still be a lot cheaper than some of the fancy aluminium tracks I've seen advertised.
You got it!
 

anoccasionalyachtsman

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15 Jun 2015
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2,733
A full length batten from clew to meet the luff at a right angle works like a boom on some boats, and could be added relatively easily.
 

TLouth7

Active member
Joined
24 Sep 2016
Messages
478
Location
Edinburgh
Interesting. Why would the sail prefer not to go all the way to the end on a rope track as opposed to a rigid track? Is it because the rope track would inevitably deflect upwards a bit no matter how much it was tensioned and the sail would refuse to go further out on the "downhill" bit of the rope since it would then be trying to go tighter?

Also not sure how the presence of a boom would remove the need for the track and still be self tacking, except possibly if it was rigged as Wallacebob suggested at #4?
Indeed. Additionally on some/many boats when close hauled the sheet will actually be pulling slightly inboard on the car, so even a straight track might not work. Consider that if the clew is outboard of the sheet car then the bottom of the leach must be hooked which is generally not desirable.

A boom separates the sail tension and sheeting angle functions. A single sheet from the centreline defines how far out the boom can swing. Or you can keep the straight track and use the sheet to apply leach tension (like a mainsail boom).
 
Joined
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1,324
Indeed. Additionally on some/many boats when close hauled the sheet will actually be pulling slightly inboard on the car, so even a straight track might not work. Consider that if the clew is outboard of the sheet car then the bottom of the leach must be hooked which is generally not desirable.

A boom separates the sail tension and sheeting angle functions. A single sheet from the centreline defines how far out the boom can swing. Or you can keep the straight track and use the sheet to apply leach tension (like a mainsail boom).
Thank you, very useful.
 

Iliade

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Joined
27 Apr 2005
Messages
1,598
Location
Shoreham - up the river without a paddle.
also have a curved track, but I cant understand where you have rope friction the prevents the car from moving. For optimal operation the distance from head stay to track should be some mm shorter in the middle of the track than at the ends. That way sheet tension is automatically slackened during the tack.
I don't think the sail is big enough to overcome the double ended four pulley (five sheaves) set up. When sheeted for beating it usually just stays at the same side until kicked. It works better when off the wind, but it is less important then...
 

Iliade

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Joined
27 Apr 2005
Messages
1,598
Location
Shoreham - up the river without a paddle.
I've been toying with the idea of a boom but getting a useful angle on the kicking strap could be a challenge. The whole lot would probably get in the way of using the chain locker too!
Maybe really push the boat out and try a rigid strut acting downwards as per the racers' mainsails; Could be goosenecked to the stay then operated by a multiple purchase downhaul. This would also permit it to let the boom rise out of the way for anchoring.
 
Joined
6 May 2020
Messages
1,324
Maybe really push the boat out and try a rigid strut acting downwards as per the racers' mainsails; Could be goosenecked to the stay then operated by a multiple purchase downhaul. This would also permit it to let the boom rise out of the way for anchoring.
Blimey, there's food for thought! Cheers.
 

lw395

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Joined
16 May 2007
Messages
42,083
The IC's with jib booms sometimes had/have the jib luff forward of the boom's pivot, so the luff tension pulls the clew down?
I haven't explained that very well have I? :)
I think a perusal of model yacht books might be in order, they've done all this and their experiments are cheaper!
 
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