jib luff wire question

[Chincoteague]

The luff wire in my jib is fixed at the tack and loose at the head. The head cringle is not currently lashed to the luff wire thimble. If I pull the sail up along the wire it comes just short of reaching the end of the wire. Is this where I want to tie it? I believe that I want the halyard tension to all be on the cable, right? So when I tie the head of the jib to the cable how tight do I want to pull it up? If I tie it too close then really haul on the halyard would there be enough stretch to transfer too much tension to the fabric of the luff? What is a good starting point for how much slack? Is this a trial and error process? Thanks for any advice.

[tomodda]

So strange, it's like everything is backwards on your boat. As I've written, your PO really was an odd beast, maybe his mother fed him sour milk as a baby? Anyway, I'll write about how my jib works and let's see if we can figure something out for yours.

My jib also has a luff wire, but fixed at the head and loose at the tack, apparently exact opposite of yours. I shackle the tack end of the wire to my stemhead fitting, and then tie the sail tack itself also to the stemhead. I just use a spare bit of Dyneema (@GL: Because why not?) and tie a loop going from right behind where I snapped the wire on the stem to the cringle at the tack and back, tying the whole thing off with a few clove hitches, simple. The "secret" is how long I make the loop - basically I tie it short if I expect higher winds, medium for "normal", and long if I expect a low-wind day. That's my rough adjustment and then I use halyard tension to adjust for actual conditions. Being as I am a control freak, I also put in a jib-halyard tensioning rig to do fine-tuning. All that being said, I think I adjust the jib halyard tension maybe twice-thrice a day at most. Im not racing, so it's just for major changes in windspeed (and I HATE scallops).

I'm not sure how my approach would work with the tie at the head of sail instead of tack. Thinking while writing.... with my tie off being at the tack, the "force" of the halyard is goes thru the sailcloth (or at least the luff of the sail) until all the slack comes out of the luff, then it's borne by the wire. OK.. now on your sail, it should work the same way, no? Both ends of the sailcloth are fixed to the wire, one way or another, and there's a bit of slack in the wire itself. As long as there is slack in the wire, you're halyard is acting on the sailcloth, which is what you want. Once you've pull the slack out (luff is stretched to same length as the wire), then the halyard will pull on the wire itself. At that point, pulling on the jib halyard will cause the hounds of the mast to be pulled forward, further bending your mast, depowering your main. Which is why I do a rough adjustment for wind conditions via the length of my "jib loop" - shorter means that the slack comes off sooner and I can bend the mast with less yanking on the jib halyard, longer is vice-versa. There's been some rare occasions where I've cursed my fates, but the bow to the wind, lay myself out on the foredeck and retied my jib loop - all due to a major windspeed change, weakening winds of course. You can't do that, you'd have to drop your jib, but it's so rare that I wouldn't worry about it.

Well, that's my take on the wire luff. Answering your other questions, the length of your jib tie/loop is found by trial and error, but you want the tie+sailcloth length to be roughly equal to the wire length from head to tack with just a bit of slack for the wire. By slack, I mean that the wire is not taught enough to strum a note, like a loose guitar string... I don't mean that it's flopping around. The difference between a "short" jib tie/loop and an "long" one is maybe two inches - or to put it another way, when I have it tied off long, the wire is just almost wanting to flop around. I have no idea how you will get a feel for this with your tie-off at the jibhead instead of tack, but I'm sure you'll figure it out! And lastly, as I wrote above, you DO want the tension to go on the fabric of the luff, right up until you DON'T (low wind/high wind). It will all make more sense once you rig it up, try it out on your driveway with no mainsail and a light breeze (just to fill out your jib). Check out how the luff behaves as you tighten the halyard and then how the mast starts to bend. Then go sail, you'll soon get a feel for it!

Fair winds,

Tom

[GreenLake]

Tom, let me describe my setup, to give another data point.

My sailmaker, who used to make the winning sails for the DS (in his day) attaches the luff wire (replaced by Dyneema in its last incarnation) at the head. At the bottom is a lashing: from tack cringle in the sail cloth to -- not the stemhead, but to the bottom eye on the luff wire, the one that will be attached to the stemhead.

That way, you can remove the sail without having to un-tie the lashing.

The luff wire is tensioned with the halyard, and will take over much of the load from the forestay at high tension. The lashing works like a Cunningham, regulating the tension in the sail cloth. The main tension is supposed to be in the wire, not the cloth, according to same sailmaker; the forestay also becomes a backup and no longer the primary.

My jib halyard cleat is particularly awkward for getting a tight halyard and impossible to adjust. So I'm using a single floating block with a hook to hook into the halyard and tension it (the effective purchase is 2:1, which is sufficient for anything but the top wind range).

Changing the halyard tension does two things. It controls the sag of the sail (curvature of the luff wire away from the wind) and also the formation of "scallops" between hanks on the luff. I usually adjust to the point where those disappear. I've not adjusted the lashing because I don't see anything like wrinkles that make we question the tension in the cloth. It seems to be fine as pre-set by my sailmaker.

(The cringle in the cloth at head of the sail is similarly fixed to the upper eye on the luff wire. That lashing I would only ever change if I felt the need to have the whole sail come down an inch.)

Presumably, one could replace the lashing at the tack with a real downhaul line, lead to a block near the stemhead and controlled from the cockpit. That would make sense for someone who understands when to adjust such a Cunningham on the jib (and needs the fine tuning to win races).

[tomodda]

@GL:

Calling the jib tie-down a "lashing" definitely makes more sense, thank you. I still think that the tension from halyard to tack goes thru the jibcloth untill you have the halyard tightened up hard, then it gos thru the wire. Functionally though, your description is the same as mine - once tied, dont mess with the lashing, keep the whole rig tight enough to eliminate scallops, keep it looser to belly out the jib (draft forward) in light airs, tighten it up in heavier wind. And yes, as you tighten the halyard, the forestay becomes just a backup. And I'll try tying my tack lashing to the bottom eye of the wire. Don't think it'll change much, but let's see.

@Chincoteague:

As you can read, there's different ways of looking at the luff wire, but bottom line is you'll have to play with it and get a feel for your jib. Between luff tension, your jib tracks, and the barber inhaulers, you can control jib shape quite nicely.

Tom

[GreenLake]

The tying to the luff wire eye that's attached to the stemhead instead of directly to the stemhead changes nothing in how it works, but everything in how much effort it is to take the jib off. If you keep your boat on a mooring you might not care, but for me, tying a lashing each time I want to sail would be a deal breaker.

[tomodda]

It's an extra 30 seconds to tie, but of course all those little "extras" add up. I'm more interested in consistency, anything to eliminate variables! I will tie off to the wire eye for the tension that I usually like and see how I feel about it.

[Alan]

jib tack luff wire and lashing resized.jpg (168.18 KiB) Viewed 16842 times

GreenLake,

is this the sort of lashing you're talking about? This is what came with my Intensity Sails jib. I had to adjust it when I first got the sail, and it took a while.

[GreenLake]

@Alan: Nice picture. That's what this looks like on my sail.

@Tom: I fight for every 30 seconds and every step I can shave off of rigging/de-rigging. It's not only the time, but also not being able to forget.

I leave mainsheet, traveler and jib sheet rigged (except that I use a soft shackle to connect to the jib). I would leave spinnaker sheets rigged, except it's not possible to secure them for trailering (and it's too easy to have them end up inside the stays). But I don't take them off the sail.

Vang and jib-halyard tensioner simply get hooked on or in (I don't bother with taking the vang off the boom). So those are steps I added.

And I also use knots instead of shackles for main and spinnaker halyard. In the first instance, because I noticed that the shackle limited how high I can raise the main by a small amount. For the spinnaker, using a knot means that both ends remain symmetric. So, I put up with that.

The new electric motor is quicker to set up than the trolling motor was, so that's a gain.