LEACH FLUTTER

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C

CHET P

I WENT OUT RACING ON A FRIENDS 2004 HUNTER 41 WITH IN MAST FURLING LAST WEEK. WHAT HE EXPLAINED TO ME AS AN ON GOING PROBLEM WAS THAT WE HAD LEACH FLUTTER AND CUPPING ON THE WINDWARD SIDE OF THE SAIL. NO AMOUNT OF ADJUSTING OF THE LEACH LINE HELPED AND THE USUAL TIGHTENING MADE IT EVEN WORSE. THE WIND WAS BLOWING 15-25 AND WE HAD TO REEF BOTH THE MAIN AND JIB TO CONTROL THE BOAT. WE WERE DUMPING THE MAIN USING THE TRAVLER BUT EVEN SO WE HAD A HEAVY HELM. HAD TO EASE THE MAIN SHEET TO REGAIN CONTROL ON SEVERAL OCCASIONS. WOULD THE VANG HAVE MADE A DIFFERENCE (I SUGGESTED THAT BUT THE OWNER SAID HE HAD TRIED THAT BEFORE WITH NO HELP HELP
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
Sounds to me like

the sails may have been blown out (hard to imagine on 2004 boat), the topping lift was set incorrectly not allowing the leech to flatten, or that the sails were not cut properly to start with. A few friends of mine with in-mast furling have gone to furling mains with vertical battens which has helped a lot in maintaining proper sail shape.
 
Jun 16, 2005
476
- - long beach, CA
The vang

the halyard and the outhaul must be set up fairly hard for that much wind and the traveler let down a little. The sail must be as flat as you can make it, which will still have some shape. Telltales off the leach are invaluable.
 
Nov 28, 2004
209
Hunter 310 San Pedro
Heavy Helm

I often sail hy hunter 310 in winds of 15-20 knots around Hurricane Gulch. When I purchased the vessel 3 years ago the weather helm was very hard in those conditions. My solution was to reduce the mast rake slightly moving the c/e forward and having a new main built. Most Hunters come with a 110 on the head and a mast rake more suitable for a 135. The caution on adjusting mast rake is to insure that you never develope lee helm! Dennis W. S/V FullSailed
 

Mike B

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Apr 15, 2007
1,013
Beneteau 43 Baltimore, MD
Genoa lead cars

Another posibility. Depending on where he had the genoa lead cars set they can cause the same problem. Basically they prevent you from sheeting the sail in properly which can cause the flutter you experienced.
 
C

CHET P

thanks

THE LEACH FLUTTER I REFERED TO WAS ON THE MAIN. I DID MENTION THAT WE TRIED THE LEACH LINE AND IT STOPPED THE FLUTTER BUT CAUSED THE CUPPING ON THE LEACH TO GET EVEN MORE PRONOUNCED, ALMOST TO THE LIKE A LETTER "C" WHICH I DON'T THINK IS WHAT WE WANTED. THERE ARE NO BATTENS IN THIS SAIL HAD NO PROBLEMS WITH THE JIB AS THE CARS WERE IN THE RIGHT PLACE, ONLY THE MAIN..... VANG?????
 
J

joe

cupping....

... I'd give the sailmaker a call and install some vertical battens... that's the main purpose of battens, to support the leech and discourage fluttering. tightening the leech line till the edge cups is detrimental to the sail's effeciency.
 
Mar 21, 2004
2,175
Hunter 356 Cobb Island, MD
Chet A few years back

We have a 2003 H356 which had the same problem. These sails were produced by UK and made in the far east. Several folks on this site had the same problem sometimes the flutter was so bad you thought the arch was going to come off. UK reported that it was a bad cut of the sail. They took them back and re-cut the sail. Since then I've not had any problems. You might try checking the archives for years 2003 - 2004 for this discussion. Jim S/V Java
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
Boom Vang

Chet: You are correct in suggesting the use of the boom vang to control the problem your friend is experiencing. The vang is one of the most important sail trim controls on the boat. I assume your friend has a boom vang. The first thing one would use to control leech flutter is the leech line but the result of too much cranking on the leech line results in a cupped main. Normally, you adjust the leech line just enough to stop the fluttering or "motor boating sound". When reaching and running you can also use the leech line to bend the battens thus giving the mainsail more camber (shape/depth). How that works is this tightening of the leech cord prevents the top batten from twisting off because the leech cord holds the top batten in line with the boom. It is hard to diagnois a problem from a computer but I think (actually I don't think I know) the vang might be the answer to your friends problem. Take a handkerchief and fold it to make it look a sail. Hold the top corner and pull on the clew part and see what happens to the shape of the cloth - it flattens out. Your pulling on the cloth is what the boom vang is doing. The fact is that the boom vang effects the leech of the mainsail throughout the entire arc of the boom. which includes reeching and running. I've been in similiar situation where the skipper does not want to try this or that control. You can't say this but in my case I tell them you invited me on the boat to help with your sail trim so indulge me and crank on the vang!!
 
B

Bob V

Performance vs Convenience

I thought that those who choose in mast furling where aware they were sacrificing good sail shape for convenience. Love my Dutchman system now that I've got it properly adjusted but I do need to leave the cockpit to put the ties and sailbag on. It's worth it. Bob V
 
Sep 20, 2006
2,953
Hunter 33 Georgian Bay, Ontario, Canada
Not really sacrifice

Bob, he shouldn't have to give up the ship to have in-mast. He asked how to trim the in-mast main, not your opinion on whether he should have a dutchman system or in-mast system. The main should not flutter even with the in-mast, which was his question. Chet, as Don said try using the vang to bring down the boom. Make sure the topping lift, and the leach cord are loose, tighten up the outhaul, make sure the main is all the way out and not still wrapped on the furler and use the vang to bring down the boom. Even one wrap on the furler will affect the shape. BTW, take off the capslock, you don't need to shout.... we're not that old in here. ;)
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
Don: while your advice

is right on target for a main with partial or full length horizontal battens, I would doubt the boat in question has any battens at all -- which is certainly part of the problem.
 
M

Marc P

356 Flutter

Had the exact same problem on my 2003 356. See Jim's comment below. UK had to recut the sail which made a big difference. It was a known problem and did not cost us anything. Marc
 
D

Doug H-36

Re Cui Then Replace

Had this problem on my 04. They tried a recut and they replaced the sail. Works great now but you may be too late for warranty.
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
No Battens

First of all, I'm no expert on in mast or boom furling. If the sail in questions has no battens, sail trimming and shape become more difficult. Why are battens installed on mainsails? Here's the reason why. Full or partial battens provide rigidity to the leech of the mainsail. The luff of the sail gets its rigidity from the mast and the foot gets it rigidity from the boom. The leech has no rigidity without battens and that is their only function. Mainsail furling systems are nice but their function is to make sail storage easy and that is where the trade off starts. Sails are designed to be sailed and storage is a secondary consideration. I could never afford a mainsail furling sytem but if I were given the choice between in mast furling or boom furling I'd go with boom furling simply because of the batten situation.
 
J

Jim Kolstoe

My 2 cents

Cupping is the result of overtightening the leech line relative to the wind strength. It should be tightened just enough to stop the fluttering. Don, I have to take exception with your statement about battens. Their primary function is to support the roach - the part of the trailing edge outside the line from the halyard to the clew. And they can vary in stiffness depending on their thickness, which affects how well they help resist fluttering. But the real problem sounds like teh boat was overpowered. Two solutions, reefing in and/or flattening the sails. If the sails are blown or cut too fully, it may be impossible to adequately flatten them. The heavy helm has one explanation: the balance of power between mainsail and headsail. You might read "Sail Power," or just go play with sail trim on a calmer day. You will probably find that you can do some limited steering by varying how main and head sails are trimed to move your center of effort forward or backward. Certainly it will change how heavy or light your helm is. Jim Kolstoe, h23 Kara's Boo
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Only one cent from me.

First for Don: I think your sail trim experience could really be helpful if you spent some time on a B&R rigged Hunter with the arch. The few that I have sailed all suffer from sail shape. Regardless of battens it seems like some sail makers do not take into account the shape of the triangle. Because of the arch the aft end of the boom is usually much higher than the gooseneck. With the traveler on the arch there is not enough room to tighten the leech even with the vang. So I have to agree with the guys on the necessity for a recut. May as well add the vertical battens while it's at the loft. Anyway I think it might even be worth a new chapter: "Trimming a battenless, roachless mainsail". For Chet: you do tend to type everything in uppercase Chet. Are you not seeing this on your end? Maybe it's intentional and that's OK by me. But some folks are put off by that. Like I said, my one cents worth.
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
Hunter B&R

ED (Huron, OH): I'll tell you it wasn't because I didn't try to hop a ride on these boats. I really did not understand some of the problems folks were having with the rig and boat and wanted to see for myself. When I lived in So Ca I offered any skipper of a Hunter B&R, from Ventura to San Diego, my 4 hour "On The Water Seminar" FREE where everyone on the boat goes through every position on the boat for every point of sail. The seminar would have allowed me to see the boat through every aspect of sail conditions. I even offered to throw in my book and chart for FREE. I did not get one taker!! I have no idea why I did not get any takers. Probably the Hunter owners felt they did not need any help. While in So Ca, I have been on every major brand of boat EXCEPT the Hunter. Here's another mystery to me. I've worked with a number of racing crews who want to improve their position. Most were middle to back of the pack racers who were stuck and had gone as far as they could. Some were beer can racers and one was long distance (Newport to Ensenada). At least half were all girl crews!! One crew in Newport, to my and their delight, ending up kicking the crap out of the male crews. My experience is that girls make better students. Most males start off by telling me stories of how they sailed to New Zealand or some place and then ask me about the use of the topping lift as a sail trim control. It is like they have to prove something. Woman, on the other hand just come with an open mind and suck in all the info. Maybe the above is why I did not get any takers on the Hunter offer - most are busy sailing to New Zealand!! There is an old adage I use all the time regarding sail trim. I learned it from a mate in Marina Del Ray, who was trying to get his sailing club to let me conduct a sail trim seminar for them - which did not fly. He said most of the members "don't know what they don't know about sail trim".
 
Mar 21, 2004
2,175
Hunter 356 Cobb Island, MD
Don, If I was anywhere near you

I would have taken you up on your offer. When are you coming to the DC area? I'll take you out and provide the after sail rum.. Jim S/V Java
 
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