Jib sheet lead position adjustment - on fixed position leads

[Brian S]

Hey, all, my little O'day has a 110% jib, with fixed jib sheet fairlead position.

The original setup is a Schaefer wire luff roller furler, which sucked. Luff was always sagging, so I use a newer, hank-on jib.

First thing I noticed is that there's a length of line from the tack to the snap shackle for the stemhead fitting. I think it was originally intended to mimic the height of the old roller furler, and keep sheeting angles the same.

But then I got to thinking, what if I replaced that strop with something more adjustable? Would I be able to control sheeting angles with an adjustable strop, and thus have more control over my jib twist by moving the sail up and down the forestay, thus changing sheeting angles?

Lowering the tack would be the same as moving the fairlead aft. Raising the tack would be the same as moving the fairlead forward.

Or is this just a stupid idea?

Some day in the future, I'll move to a 135% genoa on a proper reefing furler, and put some jib track on the side decks. Until then, I have to keep living with my fixed fairlead position.

Thanks,
Brian

 

[RichH]

Re: Jib sheet lead position adjustment - on fixed position l

Brian, what you state is done, or was done traditionally, on the ultra fast sailing ILYA scows ..... the jib luff length is not the full luff length and is raised or lowered to attain the correct jib lead angle.


ILYA scows also do not have 'fairlead cars' that can slide back and forth and additionally have 'clew irons' in addition to being able to raise or lower the jib along its forestay wire.
A 'clew iron' is a multiple set of 'holes' in a plate that is riveted to the clew section of the jib sail ...... a 'run' of holes along the leech up from the traditional single clew position / cringle that extends for 6-8" above where the normal clew cringle is located and a run of holes 3-4" along the foot section of the clew ..... you select the proper 'hole' depending on the amount of 'twist' to match by selecting the proper 'hole' in the clew iron. Obviously this is for less than 100% LP jibs and for non-squeemish sailors who dont mind getting whacked occasionally by the flogging clew iron.

if this 'clew iron' idea seems suitable and you cannot obtain the correct jib lead by raising or lowering your jib along the forestay, I keep an ILYA scow at L. Nockamixon and will be back there in mid August; then, I can show you what a 'clew iron' arrangement is all about. Clew Irons are used on boats that rake their masts 'on-the-fly' .... and the plate usually attaches directly to a double block for extra fast jib control, .... without a winch.

 

[Joe]

Re: Jib sheet lead position adjustment - on fixed position l

I believe your geometry is sound and you will be able to change the lead block's clew angle by altering the hoist of the headsail. After you experiment with it you may find the amount of shift in hoist needed to affect the apparent lead position desired could be more than you realize. Again, the geometry, in that you're moving the long end of the imaginary line between mid luff, clew and lead block. It will work, though, and over time you'll probably become comfortable with it.

One more thing, and this is mentioned in all respect to you and hopefully won't be interpreted as being insensitive..... but the terms "sheeting angle" and "lead angle" refer to the relationship between the lead block position and the centerline of the boat. It's a horizontal, or athwartship, reference...... Many factors affect the decision on what that angle will be when setting up a sailboat..... many boats can adjust their sheeting angles with a second track located inboard or outboard one another, or setting up a barber hauler.

 

[Brian S]

Re: Jib sheet lead position adjustment - on fixed position l

RichH, I believe I've seen your scow up on the hard at Nock. I'd love to see it some time when you're back in the area, or even go sailing with you.

Joe, now that you mention it, yes, you are correct, the sheeting angle is a measurement how far off the centerline your jib sheets. Generally more acute, better pointing. We have a guy on another forum with a Precision 16, and the fairlead block is mounted out at the gunwale - horrible sheeting angle for pointing!

So, I guess there's no specific term for the angle of the sheet into the clew? Or "change the jib fairlead position to change the clew angle"?

Sheeting angle and lead angle are synonymous...

And no insensitivity taken. I'm always up for learning!

Brian

 

[Joe]

RichH, I believe I've seen your scow up on the hard at Nock. I'd love to see it some time when you're back in the area, or even go sailing with you.

Joe, now that you mention it, yes, you are correct, the sheeting angle is a measurement how far off the centerline your jib sheets. Generally more acute, better pointing. We have a guy on another forum with a Precision 16, and the fairlead block is mounted out at the gunwale - horrible sheeting angle for pointing!

So, I guess there's no specific term for the angle of the sheet into the clew? Or "change the jib fairlead position to change the clew angle"?

Sheeting angle and lead angle are synonymous...

And no insensitivity taken. I'm always up for learning!

Brian

Brian..... First of all, thanks for your understanding and maturity.... I'm a little gun shy. Anyhow, I checked in a couple of sail trim books I have.... I couldn't find a specific term, other than "lead position" .. which could mean anything..... I always think in terms of the sheet bisecting the corner angle of the clew as the neutral position, or zero bias..... moving the car forward or backward would create a bias between leech and foot..... so you could express it in simple positive or negative numbers.

Many boats number the pin holes in the jib lead track..... making it easier to preset the car, and make consistent adjustments between each side. With that in mind you could mark your adjustable tack line (the pendant or strop under discussion) and use it to simulate the pin hole numbering system. You might set the jib up while the boat is docked and take a few measurements.... then come up with some kind of marking system, and a chart, to suit your needs. A small mark on the clew, pointing at the mid luff point, will help line the sheet up at zero bias.

Making you boat perform better is always worth the effort.....good for you.

 

[jibes138]

Re: Jib sheet lead position adjustment - on fixed position l

Brian S,
Just a thought. Raising or lowering the luff will also change the position of the center of effort of the sail and effect your heeling moment. Just something to consider in your decision making. As you go through various points of sail the sheet clew angle is constantly changing anyway so unless you install an adjustable car for the jib sheet lead I'd recommend you set it up for a proper angle when sailing to windward and the rest is a compromise. That's probably what the OEM did but a larger sail will require a new position.

Another option that I have used is to take a block and tie it to a length of low stretch line. Then cleat the line to a stern cleat and you have an adjustable position sheet lead. You could tie the front end of the block to the existing sheet lead to keep the new block in close to the boat. It would be a simple way to try out if a track installation is worth it to you.