Jib Tack question

[fatire]

Hi, This is probably a very basic question which will expose my DSII noob status.

I have pictured below my jib tack from PO which has a clip that needs replacing.

Upon inspection this arrangement strikes me as being incorrect in that if the clip attaches to the headstem, what does the cable end attach to, how is it tensioned? Certainly not with that loop of inferior "twine?"

Or is the hook for something else and should I be attaching the cable to the stemhead with a missing shacle?

I have searched this forum for photos of the jib tack set-up or descriptions to no avail and my DSII manual is of no help so any guidance would be appreciated.

Thanks and fair winds,
Steve from NH

jib_tack.JPG (177.85 KiB) Viewed 9903 times

[rnlivingston]

The jib wire is attached to the stem and you pull down at the grommet which tensions the luff. On my boat, there is a wire which attaches to the grommet and runs under the deck to a magic box. I've also seen a magic box attached to the mast under the deck and used to tighten the jib halyard thus tightening the luff.

[TIM WEBB]

Wow - weird: my old jib had a luff wire, but no grommet. No wonder I could never get good tension on the darn thing!

[dannyb9]

i use a rope loop similar to the white one pictured to raise the jib a few inches so that i can see under the jib. mine is a rope loop 'shackle' that raises the tack about 5" above the deck. i dont know about the bronze clip.

[fatire]

Thanks alot,
It almost looks as though the PO was doing the opposite, clipping the eyelet brass clip to the stem and then pulling the wire with the loop!

The lashing of the wire eye through the eyelet looks very professional though, not like something the PO did, and with this present arrangement it wouldn't seem like pulling on the brass hook could tighten the luff because it is more or less fixed to both the sail eyelet and the wire eye.

If it were you (anybody!) how would you change this?

Thanks
Steve from NH

[TIM WEBB]

Danny, is your jib stock? I know I don't have 5" to spare between the head and the halyard block ... ?

Steve, looks like you have 2 options: either leave your tack grommet lashed to the thimble as it is, and make sure your head grommet is moveable, such that the halyard can tension it, or vice-versa ... ?

Durn - wish I could take a look at my old jib again to see how it's set up, but it's in storage someplace at work, and I can't find it. I believe that the tack and head were both fastened to the ends of the wire, taut, and then the wire was tensioned by the halyard. Doesn't matter. All that matters is that you have some way of getting the luff as tight as you need it to be in order to sail efficiently ...

[GreenLake]

I'm not able to take a look right now, but my Jotz sail came with that configuration (minus the bronze shackle).
The halyard tensions the luff wire. The luff tension (in the cloth) is adjustable by pull on the grommet. The lashings would provide a maximum distance between tack and deck, hence defining a minimum tension in the luff. The shackle looks like it can / could be connected to some kind of downhaul for additional control.

I haven't ever seen the need to try and play with these options, and, if I recall my discussion with Hank Jotz at the time correctly, he essentially intimated that if the lashing he put on were to be the wrong length for my forestay, I was to adjust it once.

[dannyb9]

hi tim yes i assume my jib is typical, its an intensity. i just measured the rope loop 'shackle', it actually measures 6". there is no other shackle so there is 6" of clearance between the jibstay fitting on the boat to the tack of the jib.

[TIM WEBB]

Hmmm ... interesting. Can't find my old wire-luff jib to measure it, and I don't remember, but my current (not-so-new after 7 yrs) Neil Pryde jib, with no wire, pretty much stretches from stemhead to halyard block, w/o much wiggle room. And it sure would be nice to be able to raise it a bit to see under, as the window in it is basically useless ...

[jdoorly]

The engineering trade-off, related to minimizing the jib tack height vs. gaining some visual field by heightening it, is that the jib Center of Effort rises in direct proportion to the tack height, which increases the heeling force lever arm. The solution is to raise it only as much as necessary for cruising and minimize the height for racing.

[TIM WEBB]

So, do you think that's why some DS jibs were/are made with a luff wire, and a method of adjusting said tack height? Could that be the answer to the original ? posted here? Hmmm ...

[fatire]

So based on responses my plan is to use a stainless shackle, in the position of the cotton loop in the photo, to attach the wire to the headstem. But still wondering how to get any down-force on the brass clip (or it's replacement) to tighten the luff in the vertical space of probably 2"? Magic box was suggested but those are rare and seem like a total over-kill just to pull what I'm guessing is just an inch or so on the luff eyelet. I suppose I could always install a through deck fair-lead with line led back to the cockpit.

Weird that there are no pictures or descritions of this type of arrangement, can it really be that unique?

I may also try to contact sail builder North Sails and see if they can provide any insight.

I'm not racing so this weekend I probably won't give the luff adjustment a thought seeings how previous test sails just head that snap in the headstem!

[Alan]

jib tack and head fittings.jpg (209.8 KiB) Viewed 9743 times

Here's what my jib has (head fitting on top; tack fitting below). The shackle on the tack fitting is permanently installed. The label on the sail says it's made for the Daysailer by Neil Pryde, so I assume it's made to stock dimensions.

I've been wondering if I could use a roller furler, since there's a luff wire.