What clew height do you like?
Do you like different clew heights for different types of sailing?
How would/do you measure it?
Do you choose sails based on clew height?

Upper clew for power & lower for more control. Easier than changing down a sail size.

Yes, but, what height are the upper and lower ones relatively? So brand( or model) X upper could be brand( or model) Y lower.
What actual height are the clews positioned at? And does anyone have/ know their preference?

The Naish Lift foil sails seem to have a low clew when I see them ridden locally. Seems to put the boom at an awkward angle but I've never heard any complaint or mention from the riders. Other than that, really haven't noticed many outliers and assuming you aren't talking about sails with two options that BSN101 is referring to.

I like the clew at pretty much the same height as the boom, which I run fairly high - eye height or just above for lightwind finning and most foiling, nose to just below chin height for overpowered conditions and chin-shoulder height for waves, which sometimes puts the resting clew a bit above it. Once I'm raked back my front hand is always going to be reaching up anyway.. As between two clew positions on the same sail I use the top clew for foil except when really overpowered, and the lower clew the rest of the time to free up the leech a little. I've never seen a sail with the clew so far from those regions that I'd avoid it on those grounds but I think the Naish Lift does run very low so that might be an exception.

Very interesting subject!

A higher clew gives a little more oomph, and a little support when light or being underpowered.

A lower one will help bleed off the excess, control an overpowered sail.

Never measured it, you can cheat by adding more downhaul extension.

For the same boom height a higher clew will feel like the boom is higher. So it's also a boom angle thing.

Thanks BSN101 and Manuel7, needed to know that today when I was a bit overpowered in 30 knot gusts on my smallest front wing and sail.

So according to Aerotech support, using the lower clew grommet on my Freespeed sails will reduce the twist and power in sail, but not by a whole sail size. Will give it a try next time outhaul does not reduce sail power enough. Realize I can use downhaul too, but harder to do with sail attached to board/foil, and try avoiding using too much downhaul in order to reduce strain on mast and sail.

That's great....but what height are the lower and higher ones in your sail? And how would you measure it if you wanted to compare to another sail?

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sheddweller said..
That's great....but what height are the lower and higher ones in your sail? And how would you measure it if you wanted to compare to another sail?

I think you're over-specifying this. Every sail design will be different, so the "optimal" clew height for any given conditions will vary too.

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ozzimark said..

sheddweller said..
That's great....but what height are the lower and higher ones in your sail? And how would you measure it if you wanted to compare to another sail?

I think you're over-specifying this. Every sail design will be different, so the "optimal" clew height for any given conditions will vary too.

And my Aerotech 5.8-9.0 Freespeed sails have 3 clew grommets, 4.5 Phantom has 2.