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Hi Paul
Thankyou for your advice,i sort of understand it.The Dart rigging manual gives a measurement of 525mm from the front of the tramp track to the fairlead hook i will use this as a rule of thumb.
The other thing i have noticed is that when beating and the telltales on my jib are flying to get the telltales to fly correctly on my main i have to bear away. Is this because my fairleads are too far forwards or backwards, or that my main is at the end of its life ?
Colin
I agree that the Dart 15 Rigging Manual shows the position of the standard offset fitting for the jib blocks 525mm back from the front of the tramp tube, but also 90 mm bach from the shroud plate - I'd use the latter as I think it most likely to be accurately placed. The tramp tube could be mounted a bit forward or back than standard bu Laser Centre without being noticed and not regarded as critical, or in an older boat could have been deliberately mounted a little differently following rivet failure and a decision to drill new fixing holes by a previous owner (doubtful in your case).
I think that you should proceed by trial and error each day until you know what to do, starting with the blocks positioned as close to the standard position of the standard fitting. I assume that you have 2 telltales on the jib, about a third of the way from the top and from the bottom. You should aim to have the jib block positioned so that when you luff/bear away both windward/leeward telltales drop at the same time when you reckon you have the jib pulled tight for the wind conditions, and at the same time as the mainsail telltales.
You won't be able to achieve this for all points of sailing - ie you may get it right for beating, but not for reaching or broad reaching, or for broad reaching but not for beating or reaching etc, because the positioning is unlikely to be right for all 3. So you may have to compromise, and in so doing I'd have regard to the conditions and the course to be sailed, having regard to the fact that beating is likely to be the longest part of the race (unless it's very light wind with a very fast tide against it!).
First I'd try to ensure that the rig is set up (mast rake/batten tension) so that the 3 sets of mainsail telltales "swing" consistently as you luff/bear away from the right beat. Do this "unarigged", and recall what works in different conditions (or use a compromise that seems to work ok).
You also need to rig the jib with the right luff tension - do this ashore, by tensioning up the main sheet to that which you expect to use in the conditions, and then tie the clew of the jib to the furling drum shackle so that the luff tension is taut, but not taking material tension off the forestay. If it's too tight you'll stretch the jib when on the beat or reach, probably with permanent effect, and if it's too loose you'll lose power on the beat/reach.
You also need to ensure you don't tension the jib sheet too mich for the conditions - all too easy in lighter winds. If you do tension the jib too much you will necessarily find that its angle of attack will be "higher upwind" than the main, especially with an older sail, resulting in the mainsail telltales, especially on the windward side, remaining "down".
I have the same trouble trying to get the telltales on both main and jib to "swing" consistently with my floppy 11 year old one, and even with my 4 year old sail. Some of this is due to my setting up the rig for the newer sail and not bothering to change it for the new one, but I think that some is due to the older sail itself. If I get some improvement from tinkering I'll let you know.
I recall in the advice note on sprinting that Bob (I think) suggests you rely on the jib telltales most when beating. I'm not totally convinced as it is all too easy to pull the jib sheets too tight when beating, especially in lighter conditions, as I pointed out above.
The above will look like "that's all very well, but it's going to take ages to get sorted". Sorry, but I can't help more - maybe some other Sprinters can.
