Leech Flutter

[Marc14857]

DonMany Hunter 356 owners with an in mast main (B&R Rig) have had problems with leech flutter when sailing at a reach or higher at 15 to 18 knot winds even with a tight leech line. I sent my sail back to UK who made some adjustments on the seam overlap which did help but did not totaly eliminate the flutter. I know that one fix would be to buy a new main with vertical battens however I am not ready to spend the additional dollars at this time. Can you recommend any other adjustments that I can make to eliminate the flutter.

 

[RichH]

leech flutter or too much 'twist'

Reading between the lines ..... not fluttering when on a beat but fluttering when reaching? Is that the real question/problem?What you are describing in all probability isnt really true leech flutter due to a slacked leech line, etc. If the flutter exists mostly in the 'upper' portions of the sail near towards the head of the sail; then, in all probability the boom is raising and you need to apply more vang tension and/or move the traveller more to leeward when on a reach. True leech flutter happens in the middle of the leech between the head and the clew. In trying to read between the lines of your description (keyword here: ... "at a reach") my suspicions are: a rising boom thats adding too much 'twist' to the upper sections of the sail. More DOWN pressure on the boom by dropping down/ opening the traveller adjustment AND increasing vang pressure will help to hold the end of the boom DOWN. My suggestion is to apply a full set of tell-tales on the leech and if they are streaming OK on a beat but the upper leech tell-tales begin to become unstable when you drop down onto a reach ... then you definitely need more vang pressure and/or a more 'opened' traveller. Im sure that later on, Don will start to address 'twist' and how to properly control it. (hint: tell-tales .... just like how you measure nearly EVERY other sail adjustment) ;-)

 

[Alan]

Excellent point, RichH

Vang sheeting is a very under used control. However, these boats are noted for having this problem due to the lack of sail controls made worse by the roller furling and lack of backstay adjustment. Maybe think about adding a babystay and tensioner to compensate. Na forget that, roller furling main again!

 

[Jim Seamans]

Had the same problem and check the archives

My main is currently at UK for modification and should be back soon.The boom vang did not help and went so far as to unbolt and move it back four inches on the boom to help pull down more. - didn't help. One of the boats on this forum stated it all most shook his arch off the boat. I would have to get ahold of the leech line and pull as hard as I could to quite it down.Really can't wait to try it after I get the sail back from UKI have some mpeg videos of the sail trying to beat itself to death. Will need to get them installed on my website.JimS/V Java

 

[Bob]

Tried Both the Vang and Traveller

After speaking with many experinenced sailors I tried both moving the traveller and tighening the vang. Unfortunately I did not get any positive results. I should have contacted my local UK guy and discussed the problem with them but frankly never thought about it as the frustration over the sail was driving me crazy. I decided to visit my local Doyle loft and see what they had too offer after reading a posting here (from I believe Chuck, Salem, Ma) who purchased a swing batten main from Doyle which solved the problem and added performance. My Doyle guy told me of a new sail that they were selling in place of the swing batten. It is a verticle batten main and the roach is cut fuller then the original UK sail. I decided to try it and am very pleased. No more leech flutter and much greater performance. Of course replacing a new main was a bit upsetting. In the attached picture I believe you can see the battens.

 

[Jack W--H-36]

Looks great!

Looks great! What model boat do you have?May I ask How much the sail cost?Jack

 

[Bob]

Jack

Jack,We have a 2002 H356. If memory serves me correct it was about $2500.00. I also purchased a UPS for those light wind days, also money well spent. The UPS is somewhere between a spinaker and a flasher I guess. It is on it's own roller furling system which you raise on the spinaker halyard and then run your sheets outside back to the arch through block and to your jib winches. The Doyle loft I used is on City Island. I believe you can check both sails out on their website.Bob Kellersv Kathryn, Stamford, Ct

 

[RichH]

Roller furling with vertical panels and battens?!?

Wow, ..... with the warp and weft of the sail cloth at 90 degrees to normal crosscut mode (panels and battens vertical instead of normal horizontal or radial) ... such a sail is going to be a 'royal-bear' to shape correctly ..... and keep its shape when the windloading changes.

 

[Jack W]

Thanks

I just picked up my new UPS from Doyle in City Island! I can't wait to try it out!I also have UK in City Island checking out the flutter on my main.They're talking to the factory in Asia about the cut of the leech. Apparantly they have quite a few H356 and H36 mains over there with the same complaint. I'm awaiting the outcome, but there may be a warranty issue that can be easily "fixed" by hollowing out the leech slightly.We'll see!

 

[Jack W]

Curious

I'm curious if the issue of leech flutter on furling mains exists with Beneteau and Catalina owners too--or does this appear to be just with Hunters?

 

[Marc14857]

Reply to Jack W

Jack,FYIUK at City Island did hollow out the leech on my 356 last year after consulting with Asia. It did help but did not totaly eliminate the problem. I would be interested in hearing how you make out with yours.Marc

 

[Jack W]

UK Sails

ok--I'll post my results as soon as I can.

 

[chuckwayne]

Doyle UPS

Jack, you'll love the UPS! we fly ours almost all the time except when beating to windward or really heavy air.Doyle makes the vertical batten and the swingbatten main, but they are different in use-the swingbatten gives a larger roach, and more shape control, but requires swinging the battens everytime you roll the sail in or out-and that means you have to go up on the arch on the 356. the vertical batten has a smaller roach and somewhat less control, but is virtually automatic to set and reef-better for general cruising. As an ex-racer, I went with more horsepower, but the vertical batten should be a world of improvement over the standard sail. Don't forget, having UK hollow out the leech to stop the shaking just reduces your performance even more!