JIB CAR TUNING PROCEDURE:
The basic method for determining the position for the jib cars is to sight
up the jib sheet & continue the imaginary line past the clew all the way to
the forestay. At the proper jib car position, this imaginary line should
intersect the midpoint on the luff of the sail. As the sail is reefed, the
jib car position will move forward. Shift to the forward track when the
rear track won't give you the proper geometry, usually with a foresail
smaller than about 100%.
The above procedure will give you an approximate jib car position, which can
then be fine tuned thru the use of tell tales. The following procedure can
be used for fine tuning the jib on points of sail from close hauled to a
beam reach. On any point of sail more downwind than a beam reach, you
should just use the above basic procedure since the mode of operation of the
sail changes from behaving like a wing to behaving more like a parachute.
You should have 3 tell tales about 12" back from the luff & equally spaced
down the luff of the sail. Usually, tell tales are installed with a small
window so the sail trimmer can see the tell tale on both sides of the sail
without having to duck their head under the sail. The sail is properly
trimmed when the windward & leeward tell tales at all 3 positions are
streaming backwards. The proper jib car position is determined by either
the jib trimmer pulling in slightly on the jib sheet or the helmsman
pinching up slightly into the wind while watching the behavior of the tell
tales. (This test is done slowly) If the top tell tales flutter before the
bottom; then, the sail shape is twisted too much. You should move the jib
car position forward a few inches. This will alter the geometry of the jib
sheet to cause the line to pull down more on the clew of the sail, increase
leech tension, & reduce twist. If the bottom tell tales flutter 1st; then,
the sail needs more twist & the jib car position should be moved aft a
couple of inches. Note that this effect is subtle & moving the jib car
position a few inches one way or the other is all that is required.
Peter, you should also remember to start your sail trimming with the
headsail, get it close & then trim the mainsail. The two sails will
interact & affect each other's trim settings. So, you have to keep trimming
1st one & then the other making fine adjustments. Most cruising sailers
call the sail trim good enough after about one repetition of this procedure
unless sailing conditions suddenly change drastically.
Roger Pihlaja
S/V Dynamic Equilibrium
07 Jul 2001
Steve Little also had a few points to make
Regarding your Genoa, (still talking good day, normal wind 10 to 15 mph):
Lead position on the Genoa track is very important. Check your luff. If
it is breaking (ed. "luffing") high; move the lead forward. If it's breaking
low; move the lead back. The trick is to find the perfect position so the headsail
does not luff. Luffing on the headsail is major drag. Slows you down something
awful.
One more thing to keep in mind with the headsail. Sail by your telltales. You
should have outside & inside telltales...."
On our sail there is a little green strip that says trimline. Isn't it correct that you
are supposed to aline your jib sheet up so it is an extension of this line? And we have
lowered and raised our boom with the sail out no problem, is this going to be disastrous? I
believe Elton was out with us in Newbern when we did it, that is if he didn't do it
himself.
Will Barry
Bulldog
06 Jul 2001
