When your boom is connected to the lower clew hole, it creates a slightly looser leech (trailing edge of the sail) which allows wind gusts to spill out more easily... This is usually wanted when the winds are strong enough to max out or overpower the sail.. Basically if your thinking of applying extra downhaul to depower the sail, use the lower clew hole. Use the top clew hole in all other conditions....

Its a spare in case the other one rips
Its a mistake, they put it in the wrong place and had to do another hole

sorry, haven't got a clew?

nick0 said...

i use lower as im quite short and it feels wierd when the boom head is higher than the tail

Which in a roundabout way probably works well, as if you are short you are probably light, so more twist works better

mineral1 said...

Sue easy to remember.
High winds, use low clew hole.
Low winds, use high clew hole.
So its high wind, go low. And low wind, go high.

Unless you are light and using a slightly stiffer mast than intended, or vice versa.
Or if is gusty and it is more up than down, or more down than up.
Or....


That is why I'd rather have one clew grommet and tune conventionally, 2 holes is a gimmick IMHO

Mark _australia said...

nick0 said...

i use lower as im quite short and it feels wierd when the boom head is higher than the tail

Which in a roundabout way probably works well, as if you are short you are probably light, so more twist works better

im bout as light as they come

I thought it was: right side up, use the top hole; upside-down, use the lower one.

Mark _australia said...

Then you probably do want to use the lower hole........ unless you are using a softer mast or a mast with more tip flex (both of which already create more twist)

Using the bottom clew hole helps the cross batten twist off easier, the top clew hole reduces this twist so makes the sail more powerful.
Picture of my Racing Blade 7m clearly shows this twist, when using bottom clew hole

Bottom clew for speed (power down low and slippery).
Top clew for power (jumping and cranking upwind).

Basically it moves power up/down the sail.

I find a very noticeable difference on my old NP Alphas. I'm surprised they stopped doing making with two clews. It's the easiest thing when underpowered to use the top clew. Leech tightens noticeably, probably about same as 2cm downhaul adjustment.

Both at the same time if you're perverse.

sboardcrazy said...

Thanks! Glad I asked. I actually had to write it down to make sense of it all.. I've made a note to stick in my gear as I'm sure by the time I use that sail again I'll have forgotten!

I have a golden rule with all this sort of stuff, use what feels 'right' not what other people necessarily tell you, experimentation is your friend*. Look at rigging guides on sails for example, don't just rig exactly to the guide, experiment, find what works best for you and then rig to that. At the end of the day those settings might work for a particular sail on a particular mast (the one rigged at the factory) but it may not work on yours, nothing is ever the same. Plus you have to factor in how 'those in the know' like their sails rigged which may or may not work for you.

*Obviously within reason, there are definitely ways to rig a sail that may work but are certainly not anywhere near ideal.