Genoa leech line advice

[Jools_of_Top_Cat]

Got a lovely new genoa from Kemps. A big recomendation, great family business, great service and friendly to deal with. If I had one small niggle I sometimes found that they were slow to return my calls, but always appologised as they seemed genuinely busy, this is a good sign, I would rather this than a company who did not have customers.

I would appreciate any advice from those who know about leech tension lines, I have one on my main but have never seen one on a genoa before. This new sail has one; how do I set it, when should I adjust it, what exactly am I looking for.

One thing that strikes me is to set it while the sail is under power it means hanging over the rails and attempting to draw the line down and then tying it off, a little difficult I thinks. Or is this facility there for later on in the sails life to counter any stretch and flatten the sail to get a few years extra use.

Any advice gratefully accepted, like I said I have never seen a leech tensioner on a head sail, I always presumed this function was achived by the tension of the sheets and position of the traveller.



<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/Honda_00.html>Honda Formula 4-Stroke racing</A>

 

[MainlySteam]

If only of cruising concern, suggest just tighten it enough to prevent leech "flutter". Supposedly tighter in heavy, lighter in light but for cruising purposes I find one tightness does all (big furling overlapping genoa used upwind 0 - 30+ knots before change down to a staysail on an inner stay). At least better than hanging over the side (the wet side at that!), especially if the clew is cut high.

John

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[Twister_Ken]

Leave it off until the wind builds enough fopr the leech to start fluttering. Then tighten it just enough to stop the flutter. If the wind continues to build, and the leech recommences a flutter, repeat (ad infinitum).

Just tightening it up and leaving it will result in sailing with a hooked leech (=brakes) most of the time.

Don't forget to ease it when the breeze lightens.

In my experience the real problem with leech lines is that they refuse to stay cleated off. The line itself is very small diameter, and no-one makes a jamming cleat that works well on that sort of line.

PS - few things more annoying than sailing with a leeech flutter that you can't kill.

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[vyv_cox]

I can find nothing in Ken's post that I was not going to say myself.

I find that in wind speeds just (or over) that which should have led me to reef, the tension needed in the leech line is more than I would have expected. Hood tell me that this is due to differing amounts of stretch in the sailcloth and UV strip. It can be corrected or at least improved but is not a real problem. The sail looks rather hooked but since this only happens in 20 knots across the deck it is not significant.

Otherwise, as Ken says, tighten until the fluttering stops and release when the wind lightens.

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[MainlySteam]

In case of any misunderstanding we have found that we do not suffer from leech flutter or a hooked leech without adjustment at various wind speeds once it was set up. It is possible to cut a sail so for cruising without much compromise (we use it in up to 35 knots on the wind if the distance left to run does not warrant changing back to smaller foresail on the inner stay and over 40 knots off the wind driving the boat to hull speed). The sheet cars are properly adjustable (fore and aft only) over the full furling range of the sail, which is always a help to setting.

However, I have to say the sail I was referring to is not a race built sail nor is it similar in any way to some of the cheaply built sails I see appearing on production vessels. It was purpose built for a custom built boat and I guess that comes at a price. Perhaps the best advice is that it depends on the sail - light build (or you race), you will have to adjust the leech line, stronger build, less so or even not.

I do not disagree with the comments made, just we are perhaps talking about different circumstances. My comments were limited to cruising, as I said, and perhaps, on reflection, I should have qualified that further as being dependant on the sail.

John


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[timevans2000]

Hi Jools,

I have a Kemp mylar Genoa with leach line and foot line.

In practise, I seem to have 3 settings for leach line tension.

none-light wind
a little-moderate wind
a lot-howling!

Tension in the leach is only really an issue when going to windaward on my boat. Reaching the line to windward is not a problem.

Once we get well reefed we have usually put sufficient tension in the line before it becomes impossible to reach, as the cleat rises above hand hieght.


hope this helps


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[MainlySteam]

Is it going too far off the thread to ask how one adjusts the leech line when a furling sail is wrapped to one of its tack points (same for foot line if it has one)? In heavier weather when the sail is wrapped to its 85% tack point, say, and the need arises to tighten the leech line because of the heavier leech loads, much of the line will be wrapped also.

Is a genuine question; as I have said, I never have had the need to adjust ours as a matter of course.

With respect to Ken's comment about the reliability of cleating the clew end of the leech line - the double velcro systems seem to work ok on furling sails.

John

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[Twister_Ken]

>the double velcro systems seem to work<

Not sure I've ever seen it. How is it arranged?

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[MainlySteam]

Well I would have to look closely at mine, but is bagged on the boat for winter. If the clew is close to the top of the bag I'll have a proper check this weekend. But, best I can recall, the leech line has a long strip (maybe as much as 200mm) of velcro sewn to its end. The leech of the sail above the clew has the same which you stick that on the leech line to when the line is at the desired tension. Then there is another flap of sailcloth sewn along the leech also with velcro on which folds over onto the top of the leech line piece. As I say, as best I can remember. The velcro is, again from memory, about the same weight stuff they use in batten pockets on mainsails.

John

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[Gunfleet]

sail bagged for winter

This is the first mention of the 'W' word and it's only August. Please leave the class

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[Aja]

Ken

Works as a sandwich - velcro stiched on the sail with a double sided piece of velcro attached to the leech line and a flap of sailcloth stiched to the sail with velcro in the inner side which folds over leechline velcro and adheres to velcro on the sail. Quite nifty and seems to hold in any weather.

The folded over flap is probably about 9" long by 4" wide on a 30' boat to give you an indication of size.

Donald

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[Aja]

Re: sail bagged for winter

Well it is w***** in the southern hemisphere...

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[Gunfleet]

antipodean w****** season

I didn't know he was in the antipodes and I am sorry for him that it is w***** there. However, I still don't want to hear from him or anyone else about w***** because w***** lasts too blooming long when it's here.

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[MainlySteam]

Donald, you have explained exactly as it is done.

I suspect, but stand to be corrected, that apart from cloth weight, build, etc an important influence on the propensity for a leech flutter on a foresail is the horizontal length of the foot compared to the vertical height of the sail. As the sail is designed more and more for longer foot compared to height, the angle of the leech with the airflow over it increases so that a greater length of leech is presented to the same area of flow (consider what the leech would do flutter wise if it were able to be horizontal). If that is so, then one would expect a blade to be more prone to flutter and I wonder if that is so?

Another may be the width of the slot with there being less acceleration through wider ones. Our mast is set well back (is rigged as a "scutter") so the slot is quite wide, and also the genoa does not overlap as much as one might expect in a sailplan where it comprises more than 50% of the total fore and aft sail area.

Top Cat, from Julian's photos, has her mast even further back than ours so the slot will be wide with little overlap, even though the genoa appears to be a large part of the sailplan. So it may be, depending also on other factors, that Julians leech line does not need much, or any, adjustment between light and heavy wind speeds.

I accept everything all have said, so am not disgreeing - the proof is always in how it turns out on the water. So, therefore, I don't have to get nasty and tell you how the buds are bursting and the shoots are sprouting 'cause the big W word is nearly gone here.

John



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[Aja]

John

I would suspect that what you have said is true. I dont have any flutter or hooking on my No3 but have had to tighten the leech line a bit on my No2. Both sails are not in their first flush of youth. But as you would expect, the leech length in the No3 is not much shorter than the No2, but the sailcloth weight is significanlty less.

The nights are fair drawing in here......... should start going into terminal decline very shortly up here in Scotland.

Donald

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[Jools_of_Top_Cat]

Thank you all for the advice, I did not notice any flutter at all with the tension that has been applied by Kemps in the position in which it has been tied off by them on delivery.

As I said I have never seen one on a genoa, I do know this sail has turned the boat around as far as performance, my origional genoa was probably origional. My pointing ability has made Top Cat actually feel a little more fun than hard work to go anywhere.

My pennies are now going in the jar for a new main, but as she is genoa driven this is not I think going to have the same dramatic effect as the new head sail.

I might have a look at this velcro idea, seems to make a lot of sense, pulling down the line and tying a fig of eight etc seems like a very rough way to try and set tension, whereas little adjusts and hooking velcro seems a great way to a. get it right; b. play with the sail to get maximum performance.

So once again thank you all for very clear and interesting information.....

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/Honda_00.html>Honda Formula 4-Stroke racing</A>