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joethewindsufa
Joined: 10 Oct 2010
Posts: 1190
Location: Montréal
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 Posted: Fri Jan 09, 2015 8:01 pm Post subject: |
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@techno900 - MauiSails 8.4 to 11.0 = cambered ??
if so, one better give sufficient downhaul or one breaks battens - as u say - rig to specs
tight leech on my MS-2 8-oh busted many battens 
+ or - 2 cm ??
Art Szpunar of Maui Sails and David Ezzy have shown with loadcells that mm of downhaul make significant change in downhaul tension
the ideal range on David Ezzy's video with the loadcell was less than one cm between min and max
https://vimeo.com/51702125
AND he specifies that IS difficult to visually set DH to ideal setting every time
takes time , patience and perhaps NOTES for each sail in the quiver - Ezzy has a gadget {no stretch ?}
adjustable outhaul helps me a lot for sail range !!
best guess on DH after looking at conditions - based on experience/notes with the sails and GO  |
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Sailboarder
Joined: 10 Apr 2011
Posts: 656
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| Posted: Sat Jan 10, 2015 5:49 am Post subject: |
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| techno900 wrote: |
How many sailors in gusty lake conditions could tell the difference between 2 cm more or 2 cm less downhaul on any sail if they spent the time going ashore and adjusting?
If one only has 5, 7 & 9 meter sails, downhaul adjustments make more sense trying to maximize sail range, but if one has 5, 6, 7, 8, & 9 meter sails, rigging the correct sail negates/minimizes the need to adjust downhaul. Of course, if the wind changes much, it's better to re-rig, but if one is a little lazy, adjusting the downhaul may help a small amount if in steady (non-gusty) conditions. |
Sailing on gusty lakes, I decided to have large gaps in my quiver. The wind behaves randomly so you would have to be lucky to pick the perfect centered sail. You have to learn to sail over or under-powered.
You are right that adjusting ashore is a problem because the wind varies and you are not sure anymore after adjusting if the changes came from the wind or the adjustment. The fix is to adjust in water. I don't recall getting off water just to tune my sail in the last few years.
I usually adjust DH to be in optimal position first. If I think the sail will be marginal and the forecast is calling for increasing wind, I let go some DH before hitting the water and take a mental note of the changes (ie I had to let go a bit more than a finger width). If eventually required, I can add DH on the sail in the water, just by using that reference.
Adjusting the OH on water is quite easy with my Ezzy's because you gauge it with the little ropes at the clew. It's quite handy since you have to redo it too if you change the DH and you'd be stuck without references.
A small trick is to make sure to put a simple knot at the end of your outhaul after threading it. If it slips out of the tack while adjusting in water, it's quite difficult (or impossible) to thread back in. You don't have this problem if you use an Adjustable Outhaul or a Loop'n Go one. |
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techno900
Joined: 28 Mar 2001
Posts: 4161
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| Posted: Sat Jan 10, 2015 10:03 am Post subject: |
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Joe said: | Quote: | @techno900 - MauiSails 8.4 to 11.0 = cambered ??
if so, one better give sufficient downhaul or one breaks battens - as u say - rig to specs tight leech on my MS-2 8-oh busted many battens Embarassed |
I have TR race sails from 6.6 to 11.0 and I never downhaul less than recommended (except when new), but sometimes more. I have been with Barry Spanier's sails since the Neil Pryde days in the 80's, then Gaastra then Maui. Since the Gaastra and Maui days, never a broken batten. Most folks with cambered sails, especially those new to cambered sails, don't use enough downhaul, at least from what I have observed. Rig to specs and go.
2cm downhaul is 3/4 of an inch and can make a perceptible difference, both visually and performance wise on some sails, but generally, it's not a big deal, especially if it's only 1cm.
On Maui Sails, downhaul measuring is easy. Distance from bottom of sail pulley to bottom of mast. http://www.mauisails.com/sail.php?id=154 |
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