Slightly undersized jib

[dom]

Not a particularly special sail, but this is one of the inherent problems with them. And yes, the whole thing is setup for that beautiful 12kt beat, and as soon as you ease the sheet you lose leech tension and they twist too much. The few owners that care about it rig a pair of conventional sheets for offwind. Yes, I know it obviates the point of the things but if that 12kt beat is up a lovely river, there's nothing better than a s-t jib.

Oh, and you didn't mention roller reefing - that sucks too! A ton of foot tension and nothing on the leech. If an owner also bought an overlapping genoa from us it did come with a mark to which it could be rolled and also used as an s-t, so that helped them a bit.

The track shape doesn't make any difference to the sail's set, but it's critical to the ability to actually 'self' tack. we had curved on our boats - choosing the radius of the curve and the angle from vertical of the plane it lay in was indeed cunning! (But not always convincingly right).

Surely the vertical sheet you describe above implies that the entire drive component of the sail at the clew is acting vertically into the sky and that all of the forward drive is occurring at the forestay. There is no way a sail could meaningfully effect this transformation and a designer wouldn’t want to remove the forward component of drive anyway.

The only time this could happen is if one sheeted in the jib in a flat calm, the same effect as if one moved the track forward on a standard setup.

What I think you are describing is a high-aspect sail which will naturally have a more vertical sheeting angle, coupled with a short distance between the clew and the self-tacking track. Is this creating an optical illusion of looking vertical? Also, the problem with losing leech tension is inherent to high aspect sails.

Unless I am getting the wrong end of the stick here?

 

[lw395]

Not a particularly special sail, but this is one of the inherent problems with them. And yes, the whole thing is setup for that beautiful 12kt beat, and as soon as you ease the sheet you lose leech tension and they twist too much. The few owners that care about it rig a pair of conventional sheets for offwind. Yes, I know it obviates the point of the things but if that 12kt beat is up a lovely river, there's nothing better than a s-t jib.

Oh, and you didn't mention roller reefing - that sucks too! A ton of foot tension and nothing on the leech. If an owner also bought an overlapping genoa from us it did come with a mark to which it could be rolled and also used as an s-t, so that helped them a bit.

The track shape doesn't make any difference to the sail's set, but it's critical to the ability to actually 'self' tack. we had curved on our boats - choosing the radius of the curve and the angle from vertical of the plane it lay in was indeed cunning! (But not always convincingly right).

Interesting.
The only self-tackers I've sailed with have been on dinghies.
No overlap, radiused track with pin stops.
A few times in our early outings, I wished for normal sheets to back the jib!

 

[anoccasionalyachtsman]

Surely the vertical sheet you describe above implies that the entire drive component of the sail at the clew is acting vertically into the sky and that all of the forward drive is occurring at the forestay. There is no way a sail could meaningfully effect this transformation and a designer wouldn’t want to remove the forward component of drive anyway.

The only time this could happen is if one sheeted in the jib in a flat calm, the same effect as if one moved the track forward on a standard setup.

What I think you are describing is a high-aspect sail which will naturally have a more vertical sheeting angle, coupled with a short distance between the clew and the self-tacking track. Is this creating an optical illusion of looking vertical? Also, the problem with losing leech tension is inherent to high aspect sails.

Unless I am getting the wrong end of the stick here?

Imagine taking a 100% jib on conventional sheets and moving the car forwards to under the clew (on a calm day). Sheet it for a nice leech curve and you now have a very baggy sail. Now recut the sail so that foot's the right shape too. That's the basis of a self-tacker, but you'd probably arrange the cloth to suit.

Don't forget that if you have my 'almost vertical' sheet it has more tension in it than normal, and the horizontal (vector) component can still be as large as one at a more conventional angle.

You're exactly right on the high aspect ratio, but you've got the added problem of not even being able to shift the sheet aft if you wanted to - the cruising option is a taller track (coachroof) and a smaller sail.

 

[Dutch01527]

Interesting.
The only self-tackers I've sailed with have been on dinghies.
No overlap, radiused track with pin stops.
A few times in our early outings, I wished for normal sheets to back the jib!

I did not go looking for a boat with a self tackler, I found a boat I liked and it happened to have one. I am now somewhat of a convert especially when solo or with my wife who is new to sailing. She is much more comfortable in the new boat where everything is much calmer. She is also enjoying helming more because the cockpit is less frantic. It is also safer with inexperienced people on board, we had newbie friends with young children come out for a sail and I was much more comfortable not having to watch out for feet getting caught in jib sheets or fingers in winches.

When I have my mates onboard we can always use the Genoa or hank on jib sheets to the jib and sail conveniently -best of both worlds.

 

[lw395]

To be fair, my experience of very light dinghies with ST jibs is of limited relevance, you should ignore the downside of not being able to back the jib.
I'm unconvinced that a vertical sheet with massive leech tension is the right way to cut a self tacking jib.
It is certainly not the only way.
But that does not matter.
However your sail is cut, try moving it up and down the forestay with different tack strops until you find the best compromise.
We now know that while some people aim the sheet 45% up the luff (lower than I regard as normal), some people aim it up towards 100%.
Maybe if you can get it setting and post some pix, there were be some interesting comments?

 

[Dutch01527]

However your sail is cut, try moving it up and down the forestay with different tack strops until you find the best compromise.

Maybe if you can get it setting and post some pix, there were be some interesting comments?

I dropped the sail of at the sailmaker earlier today and he pretty much said the same as you. Put it up at different heights and experiment to find what works best for your boat, no single answer.

I will post some results from the experimentation and some pictures when I get it back.