A fluttering leech....

[geem]

Fluttering leech is going to be inefficient as well as unattractive.

OP doesn’t like the hooked appearance of tightening a leech line but I wonder if it doesn’t work like a winglet in keeping the fast and slow moving air streams separate until away from the sail/wing and thereby increasing the efficiency of the sail/wing?

A hooked genoa is like putting the brakes on. In my mind if you can't stop it doing that it's time for a new sail. I have only experienced it on sails with circa 20,000nm on them. If its doing it on a new sail there is something very wrong. Stating the obvious, but have you moved the car forward to tighten the leech?

 

[[2574]]

A hooked genoa is like putting the brakes on. In my mind if you can't stop it doing that it's time for a new sail. I have only experienced it on sails with circa 20,000nm on them. If its doing it on a new sail there is something very wrong. Stating the obvious, but have you moved the car forward to tighten the leech?

Yes I’ve tried various car positions and sheet tensions. It’s quite a juggle though balancing sail draft, angle of incidence, leech tension. Maybe I’ve not yet found the sweet spot, this is our first season with the sails.

 

[Daydream believer]

A hooked genoa is like putting the brakes on. In my mind if you can't stop it doing that it's time for a new sail. I have only experienced it on sails with circa 20,000nm on them. If its doing it on a new sail there is something very wrong. Stating the obvious, but have you moved the car forward to tighten the leech?

Actually, if you read the numerous articles by sailmakers you will find that they mostly say that this is NOT such an issue as some might think. North sails comment on this very matter. They do suggest that it is very much more preferable to a fluttering leech. They also warn against constant over sheeting of the leech in the first place which can lead to a stretched leech & the inevitable flutter.

Enclosed is an extract from one sailmaker:-
When the leech flutters you will sometimes see (and hear) that the leech of your sail is fluttering. If the sail has a leech cord, tighten it until the leech just stops fluttering. Tightening can cause the sail leech to curl or hook to windward. Neither will seriously affect performance but the latter is less irritating and will reduce fraying damage.

If you look at the more detailed articles on wind flow past sails you will see that by the time the airflow gets to the leech of the genoa the work has already been done & it breaks away anyway. This is described in detail in this article:-
Aerodynamics
In fact if the sail is incorrectly trimmed anyway - which is more likely with the average cruising sailor with a poorly set sail- the airflow will already have left the lea of the sail.
Whilst a neat edge may be preferable, a hook is not as bad as it may look, if not excessive

 

[[2574]]

Actually, if you read the numerous articles by sailmakers you will find that they mostly say that this is NOT such an issue as some might think. North sails comment on this very matter. They do suggest that it is very much more preferable to a fluttering leech. They also warn against constant over sheeting of the leech in the first place which can lead to a stretched leech & the inevitable flutter.

Enclosed is an extract from one sailmaker:-
When the leech flutters you will sometimes see (and hear) that the leech of your sail is fluttering. If the sail has a leech cord, tighten it until the leech just stops fluttering. Tightening can cause the sail leech to curl or hook to windward. Neither will seriously affect performance but the latter is less irritating and will reduce fraying damage.

If you look at the more detailed articles on wind flow past sails you will see that by the time the airflow gets to the leech of the genoa the work has already been done & it breaks away anyway. This is described in detail in this article:-
Aerodynamics
In fact if the sail is incorrectly trimmed anyway - which is more likely with the average cruising sailor with a poorly set sail- the airflow will already have left the lea of the sail.
Whilst a neat edge may be preferable, a hook is not as bad as it may look, if not excessive

Interesting and comforting. So a hooked leech is just aesthetically pants……fair enough!

 

[Keith 66]

Im at the point of replacing a 6 year old genoa from a budget maker, the leech has a dirty great hook in it the same width as the sacrificial strip. Adjusting the leech line just makes it worse. Its badly stretched & rolled partway up it sets worse. Im afraid im not throwing any more money at it.
The old adage buy cheap buy twice applies.