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Mick Young 04-02-2007 05:44 PM

Depowering Jib
 
Hi people, is it a natural way to depoer the jib by running the jib lead forward on a mast head rig without a furler or am I just being lazy and should I change the jib?

Keep it black side down

Mick

ianhlnd 04-02-2007 05:52 PM

Change the jib, if you have to depower, probably need to reef, stay out of trouble and change.

sailingdog 04-02-2007 06:02 PM

I'd have to agree with Ian... If you need to depower, chances are likely that you really should have reefed a bit earlier...

The time to reef is the first time you think it might be a good idea...not doing so often ends up with the black side up....and you swimming. :D

Mick Young 04-03-2007 05:42 AM

Thanks guys, Where we are going for the eastes break there is a lot of land effects, and rather than changing and reefing I was wondering whether in those sort of conditions it was better just to depower than keep changing. The bank balance said no to a furler, so we still manually change, which I am more than happy about as it gives me the necessary experience in doing so.

Keep it black side down

Mick

GordMay 04-03-2007 07:16 AM

Take a look at SAIL Magazine's ”The Jib-trim Series” ~ by Michael Tamulaites
SAIL Magazine

Sailormon6 04-03-2007 09:25 AM

Mick, the answer to your question depends on many variable factors. Each jib is designed so that it is efficient within a certain range of windspeeds. The problem is that the wind doesn't always cooperate by blowing steadily within that windspeed range. Wind blows in puffs and lulls. One moment you may be overpowered while beating to windward, and then you sail into a lull, and you may wish you had more sail area. When you're racing, you select the biggest sail your boat can carry the most efficiently for the highest percentage of the time. You accept the likelihood that the boat will occasionally be overpowered for brief periods of time during the strongest puffs, but those overpowering puffs might only be a problem 4-5% of the time. The rest of the time, the sail area will be just right for the ambient wind, or you'll be sailing off the wind.

The sail trimming techniques that you're talking about can help extend the useful windspeed range of a jib a little bit, through short-lived puffs, but if the puffs are stronger, or longer-lived, there is a point where you're better off to reduce sail area. Other factors to consider are the length of the race, the ability of your crew to make a quick sail change, whether your boat is rigged for quick sail changes, and how much of the remaining race will be sailed to windward. If the boat is grossly overpowered, and you have a lot of windward work ahead, my inclination would be to change sails, even in a fairly short race around the buoys, because the boat will perform so much better that you may well make up the time lost in changing sails as against all the other boats that are still struggling, grossly overpowered, with the bigger sails. If the boat is only overpowered a small percent of the time, or most of the windward sailing is behind you, then my inclination is to use sail trimming techniques to keep the boat on its feet during that small percent of the time.

Gary M 04-03-2007 09:39 AM

I believe you said move the jib lead forward to depower.
That is not how I would do it. To depower a jib you would want to move the lead back to flatten the foot and open up the upper leach. You would also get as much halyard tension as possible to flatten the entire sail. In general though I would change down, lighter head sails are easily damaged when carried in too much air.

It is much easier to depower a main by flattening it as much as possible and dropping the traveler down, that is the normal way to temporaily reduce heel.

Gary

CapnHand 04-03-2007 09:13 PM

Stated in another way, moving the jib lead back allows the top of the sail to twist, spilling air from the top of the sail where the heeling forces are greatest.


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