Luff Flutter on new Main Sail

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CJ13

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We have a new fully battened Vectran Main. In winds above about 17kts apparent the luff rope flutters and vibrates against the mast. This happens at almost all points of sailing. The sail luff isn’t lifting.
The new sail replaces the original ‘low spec’ Elvstrom Main which was also fully battened- we never experienced flutter.
The distance from Mast to Sail at the intermediate batten cars is fixed. The sail maker has suggested adjusting the batten cars to achieve the same distance and this certainly makes a significant difference but the problem persists. He’s said the final solution is to attach the intermediate cars with ‘Elastic Rope’ something I’ve not heard of.
The sailmaker is in Athens and we’re in Leros, Eastern Aegea, so at the moment this is all being done remotely.

Has anyone experienced / solved a similar problem?

Thanks,
John
 
I see the same effect, at wind directions in range 80-120deg True. As you discuss, I also identified the cause being the gab between the sail and the mast. I have noticed that easing the halyard a little can lower the flutter frequency (and noise).
 
I also experienced this on my new boat with a cruising laminate sail from Quantum.
The solution suggested by the sail maker was to adjust the bolt rope so that it was tighter.
This has almost completely resolved the problem except in 15kt+ beam wind.

How have you adjusted the distance between the mast and the sail on the batten cars?

I believe that using elastic to attach the lower intermediate cars is sometimes recommended to avoid sail damage when reefing.
 
Quantum also made our new Main.
We have Selden Batten Cars. The cars screw into the batten fitting on the sail. Simply screw in or out to adjust distance from mast to sail.

Attached is a photo of the ’Elastic Rope’. Any thoughts re how much it will self adjust and how durable it will be?
 

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JFowler said:
Quantum also made our new Main.
We have Selden Batten Cars. The cars screw into the batten fitting on the sail. Simply screw in or out to adjust distance from mast to sail.

Attached is a photo of the ’Elastic Rope’. Any thoughts re how much it will self adjust and how durable it will be?
Click to expand...
The “elastic rope” just looks like shock cord. One challenge with this is it is almost impossible to retain knots, so it comes undone frequently. Our sailmaker uses some sort of metal wire clamp squeezed over the cord to join it, which might be necessary.

To be honest I can’t really see what benefit elastic connection will give. Perhaps a thin rope lashing could be adjusted to give the best length?
 
When we get that, it means that we don't have enough tension in the luff. Put some more halyard tension on and it solves the problem.
 
I also have a new dyneema Main Halyard, BS 7000kg. I’ve tried various halyard tensions & it’s made little difference.
I’ll try for even more tension, but I’m really at the limit of my strength / the winch capability!
 
JFowler said:
I also have a new dyneema Main Halyard, BS 7000kg. I’ve tried various halyard tensions & it’s made little difference.
I’ll try for even more tension, but I’m really at the limit of my strength / the winch capability!
Click to expand...
Surely you only want extreme tensions like that in very high winds so as to flatten the sail (I don't think 17kt is 'very high'). I wouldn't accept a sail that did that unless the sailmaker could come up with a convincing argument why it was the fault of the spar...

Especially as the old sail was OK.
 
When our main was delivered it fluttered like that, and the sailmaker came and pretensioned the luff rope. That stopped it completely, and we've used the main subsequently in winds up to 50+ kts. No bungee cord required or desirable.
 
Try a Cunningham, putting some tension on at the bottom of the luff rope. I'm not suggesting it will necessarily work but it may help identify where the problem is if it has an effect. You can jury rig a temporary Cunningham. You do need some kind of eyelet to attach it to, which might be a problem. Anyway it's just another idea you might he able to try.
 
Could there be too little mast bend for a sail that is cut with a slightly curved luff? If mast bend is used to flatten the sail and there isn’t already a little bend in the mast it could leave the luff unevenly tensioned and freer to flutter.
 
Alfie: The Cunningham idea sounds worth pursuing.

Braddox: Theres a fair amount of backstay tension, so the mast has quite a lot of bend.
 
I'm interested in this thread as I have the same issue. The flutter starts in the luff, then spreads to the leach. Leach line and halliard tension appear not to make a difference. If you fast fwd to 3m20s you can see what I mean in this video (just under the logo on the mainsail)


Elvstrom are very kindly looking at my sail and I'll report back on what action they take, although it sounds like the bolt rope tension may be where they start. Unfortunately I won't be able to determine if the issue has been resolved until the spring as the boat is laid up now
 
Alfie168 said:
Try a Cunningham, putting some tension on at the bottom of the luff rope. I'm not suggesting it will necessarily work but it may help identify where the problem is if it has an effect. You can jury rig a temporary Cunningham. You do need some kind of eyelet to attach it to, which might be a problem. Anyway it's just another idea you might he able to try.
Click to expand...
Yep, that's exactly what I would do, no need for anything fancy, just run a line from the goosneck somewhere, through a loop on the sail and lash it down somewhere. I'll bet this stops the Fluttering.
 
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