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Donk107 said..
Hi all
Probably a bit of a how long is a bit of string question but i will ask it anyway
One of the sailors down here who has a Sailmaster like mine has just replaced his old furling head sail with a new Doyle dacron sail that is a bit longer in the luff and foot
I am interested to get some idea what increase in performance you might expect from the new sail compared to the old one
Any thoughts would be appreciated
Regards Don
I've gone from 150% overlap to 105% overlap on two boats now, and from what I can find out it reduces average speed by about 2% in overall speed in most medium/light fractional rig racer/cruisers. A heavier masthead rigger will lose a significant amount more (maybe double that?) and a sail with a shorter luff will also be less efficient. Those figures are when using a spinnaker rather than a jib downwind.
However, that is comparing racing sails, not comparing a nice 105% with a standard 125% roller furler that will get full when reefed. Apart from poor shape when reefed, one issue with the standard roller furling No 1 headsail is that their foot length is often about 120-125% of the "J" measurement which is just about the worst length for the sheeting angle. A shorter foot (95-105% or thereabouts) allows you to sheet in front of the stays, a longer one sort of goes around the stays and further back and therefore gives you a narrower angle.
I wouldn't be surprised if most boats were as fast with a good 105% as with a reefing 125% headsail, personally.
How much you lose as a sail ages is harder to define, not just because the actual deterioration in the shape is very hard to measure but also because you can compensate for the effects of ageing to a significant extent, but only by working harder. For example, an old sail will normally be getting stretchy which will allow the draft to blow aft and the leach to blow open. If you're really working hard, you can adjust the cunningham, vang, traveller and mainsheet to compensate for most of the stretch, but that will be a continual process of assessment and adjustment just about every second of the race. If you're lazing along and not making those adjustments, the sail will just be slow.
The new sails tend to be more forgiving of less attentive sailing since their shape isn't changing all the time. Ironically, it seems that sometimes when you are absolutely at the top of your game you're less affected by ageing sails, because when you're training hard you're sailing in the groove most of the time, and can easily compensate for sail problems. That really underlines how hard it is to be accurate about this issue.
I changed the 28' fractional from a long overlap to a short overlap rig, and love it. I've now done the same with the J/36, going from a 125% dacron furling genoa to a 105% second-hand Doyle D4 carbon headsail. However, the standard J/36 is a real killer upwind in light airs because of its very low wetted surface, so even with the smaller jib the ratios are still pretty good. It would take a lot to make me put a bigger headsail back on. The easy tacking and lack of sail changes is addictive, but you do need to tweak the jib leads and fit inhaulers or you just won't point in light stuff.
Apologies if I'm teaching you suck eggs.