In mast furling mains - the good, bad and ugly

Lamps

Anarchist
560
2
The way Lamps described how he thought his leech line worked is wrong because the leech line is pulling inside the tabling on the sail from the top down, effectively making the leech shorter. The extra sail fabric relaxes along the line, cupping the leech and making the sail slightly fuller right ahead of the leech. It's not like tensioning a stay which is putting equal strain up a row of hanks up the leech, which would flatten the back end of the sail.
Ish are you even older than Bob?
I think ish should read my analogy again - or i`m missing something as I don`t understand this bit above...

 

Ajax

Super Anarchist
14,999
3,281
Edgewater, MD
The ONLY reason for a leech line is to git the leech some stability. It should only be tensioned lightly to remove the flutttering or "motorboating" of the aft edge of the sail. Motorboating results in rapid oscillations of the trailing sail edge meaning the pressue is also oscillating (not a good thing) which means the pressure is rapidly changing on both sides of the sails training edge. If you need to crank on the leech line so much that it cups the sail, it would be like trying to fly a plane with the flaps deployed..... not good for efficient flight or boat speed. If you have a sail like this get it back into the loft and have them recut the aft edges of the pannel to flatten it out!

AHHHH! sonofabitch...So THAT's why I have this "helicopter" sound when my sails are under load. Especially the jibs. The new main doesn't do it but the jibs still do. I didn't see a leech line on one of them, but I did on the other one. I'll work on setting that today.

Thanks!

Bob- Didn't you hear? 65 is the new 50!

 
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Bob Perry

Super Anarchist
31,943
1,338
Ajax:

You might check to see if your genoa leads are in the right place. That could effect the flutterring too.

Do you know how to check your lead position?

Go easy on leach line tension for reasons already discussed here. You maye be better off with some flutter rather than a rock hard, curled leach. If your sails are old and stretched it will be hard to resist tightening the leach chord but doing that will pull draft aft and add heeling moment while reducing drive upwind.

 

Ishmael

54,061
13,345
Fuctifino
The way Lamps described how he thought his leech line worked is wrong because the leech line is pulling inside the tabling on the sail from the top down, effectively making the leech shorter. The extra sail fabric relaxes along the line, cupping the leech and making the sail slightly fuller right ahead of the leech. It's not like tensioning a stay which is putting equal strain up a row of hanks up the leech, which would flatten the back end of the sail.
Ish are you even older than Bob?
:p

I thought it sounded pretty coherent, considering how close to my bedtime it was. And the answer is no. Bob's still in the lead by several years.

 

Pertinacious Tom

Importunate Member
62,855
2,003
Punta Gorda FL
Your answer makes sense. I used to think 65 was ancient. Now I'm in my 40's and my dad will soon be 80, and it doesn't seem so old.

Which won't stop me poking fun at Bob. ;)

 

WunHungLo

Super Anarchist
5,896
4
PNW
Ajax:

Yes I am.

We have gusts to over 40 knots right. Exciting!
LOL... we had gusts to 58 near Sisters on Friday...I lost the rest of my hair... :D It was solid 55 and white spume everywhere as we rounded onto the beat back.

We called the RC to report the rounding only to be told the race was abandoned and that we should find the nearest safe port. Gee thanks...the only nearest ones were to complete the race and head back upwind :lol: . So dutifully, we looked upwind at a mass of white water and criss-crossing wave trains and did the HTFU routine......3 reefs and storm jib... a few big green ones over the bow... About 6hrs later, we made Nanaimo and slept for the night.

Icon took off like a rocket in the high teens of boat speed and reported a couple of 60's. They retired before Sisters as the forecast was still a prolonged storm force.

Great design Bob...for all your grey hairs and experience with leech lines, you should be proud of that one. Nice work.

BTW Ajax... we have some pics of some mainsail trim we took for you... could be useful. I'll post them when I get a chance. They were taken with a wide angle lens to get the whole rig in, so some look a little distorted, but you'll get the idea for shape and twist.

 

Pertinacious Tom

Importunate Member
62,855
2,003
Punta Gorda FL
We went out to set race marks today in my little Boston Whaler, but the race committee sent us home because it was kind of rough. I'd guess about 15 knots sustained wind, and that's what they posted on the race results page. Enough to make little white caps, steep chop, and a couple of waves came over our bow.

I got some good pics of the Multi 23 I usually race, but those guys screwed up, did an on-course start and didn't realize it in one race, then went on to barely beat the Stiletto on straight time, getting clobbered on rated time. Uh, maybe I'm useful after all. Scary thought.

Anyway, back to the thread topic. I took this pic of one of the race boats in the cruising fleet, a Hunter 41, with both main and jib partially furled. I don't think either sail looks all that bad, and the boat was moving well. Of the two, I'd say the main looks better than the jib. A bit flat, but it was blowing enough that maybe the boat liked that shape. The jib has speed wrinkles, as all rf jibs do when furled.

hunter41reefed.jpg


 

Lamps

Anarchist
560
2
We went out to set race marks today in my little Boston Whaler, but the race committee sent us home because it was kind of rough. I'd guess about 15 knots sustained wind, and that's what they posted on the race results page. Enough to make little white caps, steep chop, and a couple of waves came over our bow.

I got some good pics of the Multi 23 I usually race, but those guys screwed up, did an on-course start and didn't realize it in one race, then went on to barely beat the Stiletto on straight time, getting clobbered on rated time. Uh, maybe I'm useful after all. Scary thought.

Anyway, back to the thread topic. I took this pic of one of the race boats in the cruising fleet, a Hunter 41, with both main and jib partially furled. I don't think either sail looks all that bad, and the boat was moving well. Of the two, I'd say the main looks better than the jib. A bit flat, but it was blowing enough that maybe the boat liked that shape. The jib has speed wrinkles, as all rf jibs do when furled.

hunter41reefed.jpg
The main shape is better than the jib because the guy has his leech line tension properly set on the main, likely by leading it back to the cabin winch - you can see the leech line trimmer is at the cabin top on the starboard side, looking up and keeping the leech properly tuned. He has to be forward of the bimini to see properly.....

Leech line trimmers are the unsung heroes of the roller main racing fleets; even though there's no bowmen to get all the glory (jib and main only racing here folks).

Lamps

 

Bryanjb

Super Anarchist
4,462
266
Various
So did we scare TheShark away?

A lot of the convenience stuff is great, people are more comfortable sailing todays boats because they don't have to deal with traditional systems that require more knowledge, strength, experience.... Roller furling sails, electric winches, bow thrusters, are bringing new sailors into the sport and I personally feel this is good for the sport. Our club is probably half powerboaters and more then one of them has mentioned they would like to move to a cat. They like the space, twin engines, no healing,,,,this is good, it's one less Searay on the water to deal with.

Shark, if you want a roller furling main get one and have fun.

 

Mojo31

Super Anarchist
4,691
0
So did we scare TheShark away?

A lot of the convenience stuff is great, people are more comfortable sailing todays boats because they don't have to deal with traditional systems that require more knowledge, strength, experience.... Roller furling sails, electric winches, bow thrusters, are bringing new sailors into the sport and I personally feel this is good for the sport. Our club is probably half powerboaters and more then one of them has mentioned they would like to move to a cat. They like the space, twin engines, no healing,,,,this is good, it's one less Searay on the water to deal with.

Shark, if you want a roller furling main get one and have fun.
Umm, scare me away from what?

We are simply considering a larger boat that provides some relief from the 100 degree + Texas heat in the summer (read bimini and a/c at the dock), room for the ocassional weekend on the boat, easily single handed, room to entertain, is about 30 foot, and is no more than 5 to 10 (at the absolute max) years old. It has to meet a price point, and I'm not interested in chasing all over the country to look for the "right" boat.

However, until the Rocket sells, I'm not in the market. But, I asked the question because a lot of the newer production "cruising" boats that you see on the lakes in the Dallas area are fitted with furling mains.

I am not a furling main fan, and don't want one. If I buy new and have a choice, I will not buy one. On the other hand, there are often deals that require compromises. Before I ruled the furling main out altogether and since I've never sailed a boat with one, I simply wanted more information.

 
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v92

Anarchist
597
4
Leech lines are not used to adjust the shape of sails. Ever.

They will allow you to stop the leech from fluttering when required. This will save the cloth and stitching from unnecessary wear and tear. The basic idea is to add just enough tension to the cord to stop the flutter. Any additional tension will just hook the leech. Please stop the nonsense.

P.S. Furling mains suck , But if you want to talk yourself into one go for it. Do a search on this forum.

 

Ishmael

54,061
13,345
Fuctifino
Leech lines are not used to adjust the shape of sails. Ever.

They will allow you to stop the leech from fluttering when required. This will save the cloth and stitching from unnecessary wear and tear. The basic idea is to add just enough tension to the cord to stop the flutter. Any additional tension will just hook the leech. Please stop the nonsense.

P.S. Furling mains suck , But if you want to talk yourself into one go for it. Do a search on this forum.
Hopefully, Mr. Lamps was being facetious with his leech-cord trimmer post. If not, I suspect we'll see him on the beach some day.

BTW, it's blowing 50 steady, gusting to 57 knots. I'm watching the trees outside thrashing around, waiting to lose power. Stinky weather.

 
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Bryanjb

Super Anarchist
4,462
266
Various
Of course they adjust sail shape, how else do you get a nice cup in the leach?

Remember the jibs that were hot knifed on the leach? Sail a couple races then bring it back to the sailmaker to get new darts and a bit more hollow.

Leech lines are not used to adjust the shape of sails. Ever.
 

Alaris

Super Anarchist
1,856
672
Annapolis
All this talk of a hollow roach. North shows this example of an in mast furler. Is a (slight) roach like this possible for the average Hood Stoway mast or do you have to have a special kind of in-mast furler to accommodate it?

45857ACB-3568-4D6E-8789-1B9F7F91CD0F.jpeg
 
^^^ They might help prevent jamming, which happens when the leech is too floppy going in, and folds over on itself. You have to keep some tension on it when winding it in.

My main concerns with battens would be:

1. With the extra thickness, they may not fit at all, or roll in and out smoothly. Our Stoway setup was packed pretty full with the sail furled.

2. Chafe going in and out of the slot. There's a lot of drag through these slots. The batten pockets stand proud of the rest of the leech, and will take the brunt of the abuse.
 
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Kiwi Clipper

Member
85
55
If you get a furling main it will not be possible to learn to optimize boat and sail performance because the vertical battens will create bumps that interfere with laminar flow of air over the lee side of the sail.
 
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