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Nacra 20 sail trim help

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(@Anonymous 7021)
Posts: 6
Topic starter
 
[#17551]

I'm having the darndest time with my upper lee leach telltale: it always wants to fly forward! I've tried everything I know...downhaul, outhaul, mainsheet, diamond wire adjustment and the telltale wants to fly forward. The mast rake is about 9" out on the rudder when measuring from the snuffer bridle. Any suggestions?


 
Posted : May 9, 2006 11:52 am
(@Anonymous 31079)
Posts: 891
 

The leach trailing edge of the main is where air flow eddies and a small tubulent seperation occurs .

If all the others are flowing don't be too concerned and take it off .

It is an indication you may be oversheting the mainsail ever so slightly in some conditions ,but the opposite error is worse so find a happy medium .

After a time tell tales will not be needed as you develop feel for the boat, as that occurs take more of them off as sailors transfixed on them will never learn to antisipate and react to the other visual and sensory aspects of sailing and racing .

Often when racing in certain conditions like starting in a crowd all pinching to windward it is important to feel the boat and stay in the hunt with them or ahead of them ,--that may require sailing slightly higher than optimum which can be very effective at times , particularly in current.

just my 2 cents ,--hope that helps .


 
Posted : May 10, 2006 10:58 am
TEAMVMG
(@TEAMVMG)
Posts: 1188
Master Chief Registered
 

I have the opposite theory - the leach telltales are the ONLY ones to look at. The European inter 20 sails didn't have any others anyway!
If the leach telltales are coming onto the windward side of the sail, then it is hooking to windward. the obvious way to stop this is to ease the mainsheet, but quite often the solution is to pull on more down haul
swift sailing

paul


 
Posted : May 11, 2006 2:13 pm
(@Anonymous 13024)
Posts: 4319
 

Into the _windward_ side??

How many leech telltales do you have on the main, and where are they positioned? Where is the

top

leech telltale positioned?
Is it an old sail, or a new sail?

Class standard

sail or a custom job. If a custom sail, made by who?

In my experience, the leech telltales should go forward for about 30-50% of the time if you are looking for power. Then you have trimmed your sail for max lift. If you are shedding power, they should stream aft all the time.

Getting the leech telltales to fly all the time is dependent on how much draft there is in the sail, how much twist is cut into the sail and windspeed. If you are unable to make it fly 50% of the time whatever you do (and you are sure you have enough pre-bend and downhaul applied), perhaps you should try loosening the top battens a tad to flatten it.

I have no experience with the N-20, but on the Tornado it is generally a good ting to have the leech telltales flying about 50% of the time. I also think it is critical to have telltales around 30%aft on a mainsail to control draft and identifying an eventual separation bubble on the windward side behind the mast. A sail with fluttering telltales creates uneccesary drag in my opinion.


 
Posted : May 11, 2006 4:52 pm
TEAMVMG
(@TEAMVMG)
Posts: 1188
Master Chief Registered
 

DOH!
Yes - absolute gibberish!

It should have said leeward side of sail!

pay no attention to me I'm going now!


 
Posted : May 11, 2006 6:50 pm
(@Anonymous 13024)
Posts: 4319
 

I remember seeing a 50cm leech streamer go to the windward side, but it is so long ago that I dont remember why and what we did to fix it <img src=

alt=

/>


 
Posted : May 12, 2006 5:01 am
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