Self-tacking jib track. Dyneema?

[anoccasionalyachtsman]

There are two types of curved track systems that I know of, one where the sheet comes along the side deck, up onto the track end, through a block on a car, on through a block on the sail, back down to another block on the car and on to the other end of the track, where it's made off or led back to the cockpit again so that there's a sheet on each side. The other has the sheet led from the cockpit, into and up the mast and out at about first spreader height, down to the car and up to the sail (or double up for purchase). I think David Thomas came up with it for UK Hunter. The former loks the best, but suffers from friction from the fact that the sheet run through the three blocks. The latter looks a bit odd, but has way less friction, only the car itself adds any. Disadvantage of both is that the sail twists off as soon as it's eased, so you need conventional sheets on it for reaching if you're bothered.

This is the long batten I mentioned, and I thought it was a Freedom Yachts thing, but I've subsequently seen much older drawings of it. They all seem to feature the odd kink in the luff, which I don't like and would chat to a sailmaker about how we could avoid it with more reinforcement. (Obviously point loading the forestay isn't a good plan). This is the route I'd go down.

 

[knuterikt]

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...

I have a 38 feet boat. Sheet is 1:2 single Block on the clew, single w/becket on car. Sheet goes up into the mast (front) out on the side down to chainplate and aft. The same as Hanse is doing. Originally it was led forward to the stem and aft but it got trapped by hardware on deck. Never felt need for double ended sheeting on the headsail.

 

[ProMariner]

Another old school approach was a jib boom, usually on the staysail, which helps hold foot tension, may be easier to bodge together cheaply than any other system? Can't see it is much worse than any other self tacking jib system, they all have compromises.

I like manually tacking headsails. Makes me feel like I did something. There, I said it. Maybe if I only sailed in a river?

 

[Kelpie]

When we bought her, our boat had been fitted with a straight track for the self tacking jib. We found that it failed to track properly under certain conditions, with the car coming to a stop about a foot from the end. This was down to a combination of sheet tension and wind strength, rather than a sticky section of track. I tried lubricating and cleaning the track and car but it made little difference- you still had to dash forward and kick the car over at the end of the tack.

I later altered the height of the supports under the track in order to give it a dip in the middle. Since then, it has tacked far better.

So I would think that even a totally straight length of dyneema wouldn't make a satisfactory track, and in practise it would always have a very slight upwards deflection, the exact opposite of what you need.

If looking to simplify and economise, I would suggest that the best you could do is to use a length of steel tubing and a shackle, just like an old school mainsheet horse.

 

[Catalina36]

When we bought her, our boat had been fitted with a straight track for the self tacking jib. We found that it failed to track properly under certain conditions, with the car coming to a stop about a foot from the end. This was down to a combination of sheet tension and wind strength, rather than a sticky section of track. I tried lubricating and cleaning the track and car but it made little difference- you still had to dash forward and kick the car over at the end of the tack.

I later altered the height of the supports under the track in order to give it a dip in the middle. Since then, it has tacked far better.

So I would think that even a totally straight length of dyneema wouldn't make a satisfactory track, and in practise it would always have a very slight upwards deflection, the exact opposite of what you need.

If looking to simplify and economise, I would suggest that the best you could do is to use a length of steel tubing and a shackle, just like an old school mainsheet horse.

Thanks Kelpie, useful experience. It's been an education since my original post because I now understand far better why curved track is needed and why a dyneema track wouldn't work. I'm visualising a length of thick walled stainless with a curve put in it and angled so that the curve is partly in both planes, horizontal and vertical, such that the sheet from block to clew is actually the in the plane of the combined curve. Using a dyneema shoft shackle to attach the lower block should eliminate the noise that some have mentioned.

Now all I need do is save up!

 

[knuterikt]

Thanks Kelpie, useful experience. It's been an education since my original post because I now understand far better why curved track is needed and why a dyneema track wouldn't work. I'm visualising a length of thick walled stainless with a curve put in it and angled so that the curve is partly in both planes, horizontal and vertical, such that the sheet from block to clew is actually the in the plane of the combined curve. Using a dyneema shoft shackle to attach the lower block should eliminate the noise that some have mentioned.

Now all I need do is save up!

How would you mount that curved pipe to the boat so the soft shackle can slide along the tube. I have installed the kit from Rutgerson the track is fixed on both ends and in the middle.
I think the roller link Rutgerson use works better on curved tracks than ball bearings.
Self-Tacking Archives - Rutgerson Marin
Link to installation
https://www.rutgerson.se/wp-content/uploads/2016/12/32mm-self-tacking-jib-system-english-1.pdf

 

[Catalina36]

How would you mount that curved pipe to the boat so the soft shackle can slide along the tube. I have installed the kit from Rutgerson the track is fixed on both ends and in the middle.
I think the roller link Rutgerson use works better on curved tracks than ball bearings.
Self-Tacking Archives - Rutgerson Marin
Link to installation
https://www.rutgerson.se/wp-content/uploads/2016/12/32mm-self-tacking-jib-system-english-1.pdf

Thanks. I'd aim to mount it at both ends but not in the middle. The sail should never be puuting load anywhere other than the ends, certainly not in the middle where the boat is head to wind and the sail is slack. Most of the track only serves the purpose of sliding the car/soft shackle from one end to the other without dropping out.

 

[knuterikt]

Thanks. I'd aim to mount it at both ends but not in the middle. The sail should never be puuting load anywhere other than the ends, certainly not in the middle where the boat is head to wind and the sail is slack. Most of the track only serves the purpose of sliding the car/soft shackle from one end to the other without dropping out.

I think you will find that theory and practice is to different things.

 

[anoccasionalyachtsman]

I think you will find that theory and practice is to different things.

Indeed.

@Catalina36, you mention the double curvature. We found that what worked best was a single bend, but not oriented as you'd imagine. Commonsense says that it should lie in the plane that a jibsheet might, through the clew to form a right angle with the forestay. Not so.

I've explained this on here before, and got told I'm talking rubbish, but a self tacker that fills the foretriangle tends to have an almost vertical sheet. Foot tension is largely down to the sailmaker's skill, aided by the adjustable clew board. Leech tension is huge, until you free off onto a reach anyway. For this reason the track arc should be in the plane of the sheet, pointing about 10-15 degrees divergent from the mast.

 

[Catalina36]

Indeed.

@Catalina36, you mention the double curvature. We found that what worked best was a single bend, but not oriented as you'd imagine. Commonsense says that it should lie in the plane that a jibsheet might, through the clew to form a right angle with the forestay. Not so.

I've explained this on here before, and got told I'm talking rubbish, but a self tacker that fills the foretriangle tends to have an almost vertical sheet. Foot tension is largely down to the sailmaker's skill, aided by the adjustable clew board. Leech tension is huge, until you free off onto a reach anyway. For this reason the track arc should be in the plane of the sheet, pointing about 10-15 degrees divergent from the mast.

Thanks OY. I've evidently not explained myself well. I'm not talking about a double curvature, it would just be a single bend of constant radius, but the mounting would be orintated so that the bend lay in the plane of the sheet as you describe, ie almost vertical if that's what the sheet is. I visualise somewhat less than filling the foretriangle precisely to give some angle to the sheet in order to provide some foot tension because it seems to me that the small amount of area lost would be more than compensated by better sail trim.

I don't need to worry about sail shape off the wind, which I know is a problem with self-tackers, because I have a furler-mounted genoa for that. The self-tacker will be mounted on an inner forestay (already present) solely for close-hauled work.

 

[jwilson]

On a boat of any size in any wind the el cheapo dyneema "track" would have the blocks banging the **** out of the deck mid-tack. Ever been on a breezy foredeck mid-tack and been hit by a jib clew - just a brass ring and sailcloth?

 

[Kelpie]

My remodeled track is a straight line across the beam but dips down towards the deck. It seems to work pretty well. But I have seen factory fitted tracks that curved around the mast as well.

 

[Catalina36]

On a boat of any size in any wind the el cheapo dyneema "track" would have the blocks banging the **** out of the deck mid-tack. Ever been on a breezy foredeck mid-tack and been hit by a jib clew - just a brass ring and sailcloth?

Agreed. I abandoned the dyneema track idea after the first few posts highlighted the drawbacks.

 

[Catalina36]

My remodeled track is a straight line across the beam but dips down towards the deck. It seems to work pretty well. But I have seen factory fitted tracks that curved around the mast as well.

Neat idea. I guess that allows a slightly overlapping sail but still with the two "business ends" standing clear. It highlights that the sail must be slack in mid-tack.