Sail luff lengths

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PhilUK said..
Its why Ezzy sails have a tape measure on the tack strap and a gauge on the sail to line up level with the bottom of the mast.

Which is attached by Velcro & can be moved once the correct setting is established ??

Yes, since leech twist sails were sold since 1985, none of YOU have any idea what a sail should look like so you need luff..boom..and mast numbers.
Do you also want downhaul torque numbers?

Whoever doesn't know what a sail should look like has no business asking for numbers.
Blind man don't windsurf!

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LeeD said..
Yes, since leech twist sails were sold since 1985, none of YOU have any idea what a sail should look like so you need luff..boom..and mast numbers.
Do you also want downhaul torque numbers?

Sometimes I do agree with you but in this instance you appear to be a complete twit. Most of the time when reading the numbers printed on your sail they are there so you can quickly adjust your boom and mast extension, this make rigging quicker and easier. Usually if you have the same make boom and extension as the sail then its a quick and effortless job.
The numbers are usually put there by the sail making company as that is their suggested setting for medium use of that sail.

Not all sails have little stickers on them so you get the leech right and therefore numbers on the extensions make life easier.

You don't go into a shop and say " yep, like those shoes, don't worry about what size they are I'll make them fit " you buy the size that the foot measurement tells you, you try them on and usually they'll fit.

I might also add that some sails are more adjustable than others, some have a good natural wind range and other need to be adjusted to suit the conditions.

I do look at the leech and luff tension every time I sail and don't rely just on the numbers.

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LeeD said..
So you're saying I'm right.
LOOK at the sail shape. That tells all.

No he is saying, and I agree, that appear to be a complete TWIT!

Yes exacly..and to my original point, if you rigged to the Loft to spec on my 3 mast extensions using the printed numbers on them, 1 would rig right, 1 would rig OK and 1 would rig like a pile of s..t.

The more cues we have to determine correct rigging the better. A couple of things to consider besides extension length variation. Sails dimensions, mast length, mast tip cap, mast tip strap, sail wear, and more can add enough variation to rigging a sail and throw off factory numbers. Not even talking mast compatibility!

So what do we do? Well, a sail bottom range is quite wide so underpowered no biggie, it'll almost work no matter what. Things start to matter when well powered to over powered. Downhaul tension becomes more critical and just 1cm too much can "kill" a sail where its torque is gone and the twitch is out of control.

Personally, once I know a sail (takes a couple of sessions of various wind strenghts), I try to set my extension so max downhaul corresponds to bottoming out sail against extension pulley. Then I wiggle the sail to confirm it flaps in the correct places but mostly use the downhaul distance between sail and pulley.

Outhaul is set so there's enough tension and gives a pretty solid feedback for immediate drive and trim control.

The extra 1cm that kills everything also corresponds to increase downhaul tension. It helps to wet the line for a smoother feel.

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PhilUK said..
Its why Ezzy sails have a tape measure on the tack strap and a gauge on the sail to line up level with the bottom of the mast.

Nice one.
but the real answer to the inconsistency
is
the extension doesn't have a brain , you have to use your own.
this doesn't apply to some here.

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BSN101 said..
I have some 2020 NP sails and ( NP mast & base) they both set on +20 extension and could even go to +40 to get the looseness that i look for. BUT, when set like that they are very flat so thinking that next time ill go by factory settings and see how they go, if they perform correctly when under load.

They set on 20, could go to 40 to get loose, but then they are VERY flat ?
lost me .

since you have all things NP , the factory numbers should be close, like set at those and plus minus 2cm

If you look at the Ezzy rigging videos he uses Chinook extensions and booms. I dont think I've ever seen one. I think maybe the Ezzy extension was a jokey type comment to imply it doesnt really matter which brand of extension you use to get the correct downhaul setting.

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choco said..
Maybe the sail makers should just use a Tension Dynamometer scale and how much Kn to apply for downhaul, it would be far more accurate.

That idea puts the cart before the horse.
We care about the sail shape, not the actual downhaul tension.

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LeeD said..
So you're saying I'm right.
LOOK at the sail shape. That tells all.

Lee, in a way what he said was you are right the reason the numbers are printed on the sail , are to aid in easier rigging. ( not all are as adapt without the printed word)They give you a starting point. Some of those are more accurate than others, making some hardly useful, to the more experienced sailer like yourself, the guide will be set up for the mast that's preferred, the mast extension may and often does alter the cm, or mm.
Ezzy for one, has taken this even further with marks on the sail bottom, the downhaul to align the bottom of the mast with, settings of min normal max,mdamn good guide if using a Ezzy mast) strings at the end of the sail clew, to alter from life, moderate , and maximum out haul offer guides on flatness,, and of course the folds inward at the top of the sail, Sailworks and Iam certain others have similar , visual clues to rigging, which to a trained professional like your self make it easy peasy.
i use feel to test my outhaul, knowing what I like , and can tell by feel pushing the sail towards the boom, if it's set to my satisfaction, I can feel it, it's
kinda similar to a blind man, feeling boobs, he knows them by feel.

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MikeyS said..

forceten said..

MikeyS said..
The Ezzy one is correct. Ooops, it isn't in the photo.

I haven't seen a Ezzy extension for a very long time. of course this is one. For the kids sails

www.ezzy.com/accessories/

Mr Love's point is that different brands of extensions use different "zero" points from which to measure. My point is that, as Bigdaz explains, Ezzy sails have have a system that ends up with the correct downhaul settings irrespective of the extension used. You don't need to use an Ezzy extension for their system to work. I've never used an Ezzy extension. I much prefer it to the VTS on North/Duotone.

I never could quite get the lighting on my North sails as good as in Choco's photo. Maybe it was due to my failing eyesight, impatience, or incompetence. By the way, is that sail downhauled for MAX, or medium, or somewhere in between?

The reason no one is using a Ezzy extension, is they don't supply one. On the videos the same reason , they don't sell one.

at some point years past they did, so long ago . They do supply a EXT with the children's rigs, technically it's an Ezzy but not made by them.

Thanks for the explanation, on Ezzy rigging tools, this may help others less informed to understand.
Ir respective of intent , or he said, she said, Ezzy does not supply an extension.
its called facts.

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choco said..

Basher said..

choco said..
Maybe the sail makers should just use a Tension Dynamometer scale and how much Kn to apply for downhaul, it would be far more accurate.

That idea puts the cart before the horse.
We care about the sail shape, not the actual downhaul tension.

Correct but if you know x numbers get the correct sail shape then it's fool proof

Not really, so many things affect the effort/force needed to downhaul. Just going from wet kit to dry kit would affect it massively, a few bits of sand in the pulleys, different rope, different pulleys, old or new kit. The list goes on