The last two times I've sailed I've looked at the upper telltales on the jib a lot more. I notice they break way before the lower set...well, actually I could barely get the upper set streaming nicely at any time. The upper leech was really fluttering badly.

I shifted the jib cars back, then forward, without seeming to make any difference at all

I don't think the jib is knackered. It was cheap secondhand, but looks moderately 'crisp' so cannot have been flogged to death. Perhaps the ancient mainsail is the issue?

Any ideas please? Boat is hog-stepped ali rig and I can see the position of the jib tracks has been moved inboard since the she was built in 1980.

Mags,

What usually happens with older jibs is that the leach stretches slightly over time, otherwise it may be that you are not able to get your jib cars far enough forward to tension the leach correctly.

To check your jib cars you will need to find the point on the luff of the jib that is approx 40% down from the head.  Mark this point and then on the clew draw a line towards this point that will be long enough (usually about 15") for you to assess if the jib sheet is in line with this, when under tension.  If you are not able to get anywhere near this point you may need to move the jib track forward. Also have you laid the new jib over the old jib to see what difference that there is between the clew positions, as this would also be a guide for you.

If your jib cars will not go far enough forward you can set the jib a bit higher off the deck as it has the same effect.

Hmm, so even if the jib cloth looks OK, it may still have stretched in the leech too much? Thanks for the tip about checking the angle.

Older jibs often did have quite a high clew in comparison to modern ones.  I'd have thought if the jib was knackered the whole leech would flutter not just the top bit & it doesn't really explain the telltales.  You should be able to do some sort of temporary bodge to test the principle and if you can get it to set properly then get the screwdriver out.

We found with our old smokers that the tracks were about 4" too far back, so we used blocks tied onto the ribs just in front of the cars to sheet the Jib from. Exact same problem before and after: the lower Job telltales were easy to get flowing but the middle and top ones were not. Moving the sheeting point fixed the problem, restored pointing and upwind speed.

Hurrah! I have found a potential excuse for years of poor pointing?!