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Boom clew attachment

 
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rtz



Joined: 31 Oct 2010
Posts: 248
Location: Oklahoma City

PostPosted: Sat Mar 23, 2019 9:12 pm    Post subject: Boom clew attachment Reply with quote

I'm still inexperienced enough that I can attach to any of the three settings and not tell a difference.

In what conditions do you attach to the top setting and when do you attach to the lower position?

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swchandler



Joined: 08 Nov 1993
Posts: 9460

PostPosted: Sat Mar 23, 2019 9:50 pm    Post subject: Reply with quote

The top position will yield a tighter leach, whereas the bottom position yields a looser leach. While many of my sails have a two position clew, my preference has always been the top position. I like having more sail power on tap. Still though, with proper downhaul, I still have enough looseness high up on the leach to exhaust the gusts.
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isobars



Joined: 12 Dec 1999
Posts: 19215

PostPosted: Mon Mar 25, 2019 10:36 am    Post subject: Reply with quote

When I asked my sail designer that question, his opening response was a question: "Do you prefer to sail waves/swell luffed or powered up?"

"Hammer down". (It's a preference, and in my case also a medical, thing.)

"Then use the lower grommet. The top grommet tightens the upper sail, moving the COE higher. Moreover, wind/swell interrupts air flow at the surface of the water, also shifting the COE higher because the top of the sail is more exposed to steadier wind. This higher COE adds a pitching (i.e., catapulting) moment most people do not want unless their objective is maximum jump height and duration. Luffing in that environment all but blocks that unwanted pitching effect of higher COE."
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bred2shred



Joined: 02 May 2000
Posts: 963
Location: Jersey Shore

PostPosted: Mon Mar 25, 2019 1:58 pm    Post subject: Reply with quote

This one falls into the category of if you can’t tell any difference, then there is none.

Just put it wherever seems most comfortable or makes you happiest or where the Ouija Board says it should go that day. Really, the difference is so subtle as to be non-existant.

sm
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isobars



Joined: 12 Dec 1999
Posts: 19215

PostPosted: Mon Mar 25, 2019 6:40 pm    Post subject: Reply with quote

COE height can make a dramatic difference. Tuned for big air with a high COE, a Hucker is a lot of work and can bury a sinker's nose. Yet the same sail tuned for normal B&J (i.e. lower COE) demands much less work and sails like any other superior B&J sail. (Sources include personal testing and the guys who designed the Hucker.)
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rtz



Joined: 31 Oct 2010
Posts: 248
Location: Oklahoma City

PostPosted: Mon Mar 25, 2019 6:45 pm    Post subject: Reply with quote

So on a light wind day run it at the top grommet for max power and the lowest one for dealing with higher wind conditions?
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joethewindsufa



Joined: 10 Oct 2010
Posts: 1084
Location: Montréal

PostPosted: Mon Mar 25, 2019 7:41 pm    Post subject: Reply with quote

some say - tall guys use top grommet
shorter folks the lower one

you decide Smile

the ONLY time i use bottom grommet is when i know i am overpowered
and do not wanna go in to swap down the sail
perhaps even tighten downhaul then too
if i can - on the water ...
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techno900



Joined: 28 Mar 2001
Posts: 3452

PostPosted: Tue Mar 26, 2019 7:57 am    Post subject: Reply with quote

rtz said:
Quote:
So on a light wind day run it at the top grommet for max power and the lowest one for dealing with higher wind conditions?

True of you only have one sail. Most is us will change sails (or boards) as the wind builds or drops, but as already mentioned, there are fine tuning options - adjust downhaul, or outhaul, or boom attachment point. The LEAST noticeable will be the boom attachment point, if noticeable at all.
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isobars



Joined: 12 Dec 1999
Posts: 19215

PostPosted: Tue Mar 26, 2019 10:20 am    Post subject: Reply with quote

rtz wrote:
So on a light wind day run it at the top grommet for max power and the lowest one for dealing with higher wind conditions?

No. Top grommet raises the COE, but has much less effect on total power. That pitching moment matters to any sailor, but more so to (1) less skilled sailors who still tend to get lifted onto their toes or even catapulted and to (2) people sailing boards with small forward volume, such as shorter sinkers. And for anyone who gets tired before the wind quits or darkness ends the day, the extra physical demands of managing the pitching moment matter. That jump-tuned Hucker's high COE, true to their website when I tested it, took obvious extra effort throughout the day and even more noticeable after a whole day of sailing.

Most of my boards are narrower and longer than today's super-short boards, so that pitching moment narrowed their effective wind range more so than it did my longer-nosed classic shapes. Just dropping the hammer (sheeting in) for maximum acceleration out of a hole often swamped smaller noses of some Gorge-sized (80 liter) custom boards shaped for the Gorge.
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DanWeiss



Joined: 24 Jun 2008
Posts: 2276
Location: Connecticut, USA

PostPosted: Thu Mar 28, 2019 8:09 am    Post subject: Reply with quote

rtz said:
Quote:
So on a light wind day run it at the top grommet for max power and the lowest one for dealing with higher wind conditions?


Yes. Sort of. If you are not planing and simply sailing around enjoying your day, use the top grommet as it will add more tension to the leech and balance the sail designed to perform optimally when planing. The power increase is marginal, but the sail feels more powerful due to the subtle change in leech tension.

All other things being equal, the upper grommet will increase the angle of the boom relative to the mast which can be more comfortable particularly for taller sailors. It can improve windward performance by increasing pressure on your back foot.

Yet, even though these positions do create subtle differences that can help advanced sailors engage the fin better (as odd as that may sound) the primary purpose is to adjust for body dimensions. Taller, heavier sails may like the top grommet, the lower grommet tends to suit shorter, lighter sailors due to geometry and slight changes in twist profile.
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