Flutter-Flap-Leech line

[Quoddy]

As the wind increases the jib flutters then flaps so much it pulses the whole rig.
Here’s the set up, CDI fixed halyard furler, sunbrella sun block cover, 110 with fixed block position, factory Doyle sail.
Now to fix this problem I tightened the leech line about 3“. The result was a lower leech that looks like someone pulled a drawstring on a bag. The leech is all cupped to windward and puckered. This can’t be good for smooth flow off the leech. The wind didn’t get strong enough to see if flutter/flap was stopped but at any rate this approach can’t be right, Any suggestions on were to go from here to stop the flapping leech?

 

[alexco38]

Move the fairlead backward if you can. High wind = flat jib. If you don't have a adjustable fairlead get one.

 

[RichH]

To properly adjust a leech cord, simply tighten the cord 'just until' the leech stops fluttering. If you tighten any more than 'just enough' a leech will 'cup up' and cause turbulence ..... the second most important 'aero' shape of a sail is to have the leech smooth and flat (and not vibrating) & not "cupped-up".

 

[Eric M]

Your original post hints that you had the flutter problem one day, tightened the leach and had a bad cup another day with light wind. The proper setting for the leach line is a function of the wind strength. It will require more tension to prevent fluttering as the breeze builds, while an over tight leach line will result in the cupping you observed in ligher breeze conditions. Both Rich and Alex are correct, you need to adjust the leach line and your fairlead position to get the optimal sail shape.

 

[tkaser3210]

You might also want to check how tight your forestay is - have you done any rig tuning ?

 

[Alan]

There's just no getting away from the fact that you NEED adjustable fairleads. Before adjusting the leach tension you must have your fairlead set at the correct location. Then if need be you can adjust the leach tension. Moving the fairlead forward would tighten the leach of the sail probably making the flutter disappear.

 

[Scott T-Bird]

Check that fairlead position ...

Quoddy says he has a fixed block so adjusting the fairlead isn't in the cards just yet. I'm surprised that your leach flutters with a 110 unless the wind is extremely high. I've never had that problem with the 110.

OTOH, my 150 flutters in just moderate breeze and gets a little obnoxious when up above 15 knots. Ours is a masthead rig. Adjusting the leach cord does not help (maybe it would marginally). With very little tension, the leach cups too much for my satisfaction, and the leach continues to flutter anyway. The most effective means that I find to reduce flutter is to move the fairlead _forward_. Moving the fairlead forward tightens the leach and reduces twist. Moving it back does the opposite. I find that when I am moving the fairlead back for twist (trying to read the tell tales for the optimum shape), the leach will also flutter more, so it is a game of balance. Maybe I've got that wrong so I would like to hear more.

I'd like to hear how the backstay adjuster affects flutter. I have just added mine and started to experiment. I already know that I am reducing the draft and matching the luff curve of the sail when sheeted in for close hauling.

I just find that the 150 flutters more than I like and it is part of the reason that I would cut the sail down in size at some point in time. I suspect that excessive flutter in a 110 is unusual in normal wind ranges and it may have something to do with the condition of the sail.

 

[Joe]

No matter what the fix....it's spelled LEECH......with two E's.

 

[Alan]

OOOpppsss spelling police on the prowl! ...my bad :naughty::naughty:

...it's a good thing a sail better than I spell.

 

[Don Guillette]

Quoddy: Here's my personal opinion. A 110 on a masthead rig, which I think is your setup, is equilivent to a storm jib. Even if you have a fractional rig my opinion would be the same from a sail size standpoint.

Secondly, a fixed block fairlead setup is like a broken clock. The fixed block position is correct for one point of sail and wind condition and wrong for all others. Once you move off of "correct", no matter what you do from a sail trim adjustment standpoint, you'll never get it right. The fairlead is your most important sail trim control because they are the primary sail trim control to adjust draft depth, draft, position, twist and angle of attack

I agree with Alan and to go a bit further, I wouldn't own a masthead rig without a adjustable fairlead system such as the one made by Garhauer. It was the first mod I installed on a C25 and on a C30.

With the adjustable system, the first thing you do is set the jib fairlead for the point of sail and wind conditions you are sailing on and then you mess with the leech cord.

Additionally, I think the minimum jib size for a masthead rig jib is 135. Once you set that sail for the wind and point of sail then leech flutter (motor boating) is a very easy adjustment but you can't set it and forget it.

 

[Joe]

.................Additionally, I think the minimum jib size for a masthead rig jib is 135..............

Never heard of that, Don. You mean I've been sailing with the wrong sail all these years? I use the 110 alot when I'm single handing.... I have a full roach main, though, on my Cat 27. Tht combo will get me to 5-6 kts in average conditions. I have 140 decksweeper but don't use it too much by myself because of the visibility and handling inconvenience.

 

[Alan]

Joe, of course you can choose to use any size headsail you please. You could tie a handkerchief up there and it would do something. What Don is referring to is 'better performance' from his headsail choices. The size of headsail choice is a factor of the wind speed at the time. I carry 4 different headsails to cover conditions from 1 to 40 knots and still be able to achieve a descent performance. If your prevailing wind condition is in the 18 to 25 knot range then a 110 makes good sense. In 8 to 12 knots however, the loss of 'engine' power is significant and could be improved with the larger sail.
In either case, the fairlead location is critical to correct headsail trimming. On a masthead rig the genoa is the main driving force for the boat and using an undersized sail is like driving to Aunt Millie's in 1st gear.

 

[Quoddy]

Thanks

Thanks for all the ideas, now to try them out. It is a fractional rig, which I didn’t mention because I didn’t think it made a difference in the flutter issue. It is tuned and not loose, but there isn’t a backstay so a certain amount of forestay sag can’t be helped.

 

[Don Guillette]

Joe: The cost of sails being what they are forces a lot of sailors - especially me - to make a choice of only one sail. Alan, who lives the good life living in the Hamptons on Long Island (just kidding Alan!!), has tons of money and can afford to have 4 sails.

I think the 135 used with a furler is a good all around sail that will give very good performance in all conditions. It is a good compromise for the cruising sailor.

Sailors ask me all the time for my suggestions on jib size and I tell them all I can do is give them my choice, for what it's worth and let them make their own decision. I explain that originally, on my Catalina30, I had a 155 which was pain for me to deal with single handed. I didn't like it even when I had someone to help me. I sold it on the Catalina list and with the $$ I received from the sale bought a high cut 135. The first time out with the new sail I didn't like that one either and again I sold it on the Catalina list and bought another 135 that wasn't a deck sweeper but the foot was just under the safety lines. I just love that sail.

My wife told me no more sail buying and selling. I never told her what I was paying in the first place. Like most guys, I shot her a low ball figure that is about half the price for all the marine stuff I buy. She doesn't believe me but at least she stops pestering me. With some of the marine stuff I never tell her I'm buying it. When she see it and asks me where did that come from I tell her the folks at Garhauer GAVE it to me, which many time they did, and then go on to show her how great it works. I know she sees through me but I'll bet there are a lot of guys out there that operate with their wives just as I do - maybe even Alan and you to Joe!!

 

[Alan]

I have to say my first mate is a cut above. She has never once questioned the need for anything for the boat or its cost. In fact she encourages me to buy whatever I need.
She knows I look for the best deals and limit my purchases to a self imposed budget. I don't live in 'the Hamptons' (thanks Don) and live an average middle income lifestyle. I do believe that after spending nearly $100K on my boat the cost of gear is only a small part of maintaining it.

My first boat taught me that failing to have proper sailing equipment is not worth the loss of proper sailing control. I can live without things like TV, A/C and microwaves on a boat but good sail controls are imho essential.

 

[BobM]

I had the same issue with my old boat. The flexibility of the CDI foil contributed to the issue, in my opinion. All the advice has been good. If I were to have to deal with this issue again, I would check the tune of my rigging, especially the back stay. I would also adopt the habit of changing the tension on the line attaching the bottom of the luff of the jib at the drum. I used to just "set it and forget it" but it should be adjusted for wind conditions, as is the sheet angle. I hated that annoying "squeak, squeak, squeak" as I was trying to enjoy my sail. That and that fixed baby integral halyard put paid to the CDI for me. I won't buy another. It is good value for the price but you get what you pay for. I pay a lot of money to sail. No squeaky squeaky for me again.

 

[Clark]

Guys, the OP has a Hunter 260. A boat designed to have a small jib for balance and a full-roached main for the bulk of the power. A 135 will not sheet properly. He could use an adjustable track though to get the most out of his 110.