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mewindsurf
Joined: 30 Jun 2000
Posts: 177
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 Posted: Tue Mar 02, 2010 11:01 pm Post subject: |
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damn! I've been spellingit as fut all these years. What's funny is I spelled "Leech" as "Leech" until I checked the mag and then changed the spelling in my post to "Leach."
See you in Hatteras Jerry! Gotta get back the Board Toss crown! |
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jingebritsen
Joined: 21 Aug 2002
Posts: 3371
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| Posted: Wed Mar 03, 2010 5:50 am Post subject: |
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When sailing a gale, or doing the flat water go fast thing, I tend to down haul more than when I'm doing the wave sailing thing. Free Stylers quite often do the less D/H thing. Depends on what's right for the sail/sailor. Yup, we went thru nearly 2 decades of telling most, "try a little more D/H," when asked for performance tips. Now with skinnies and lots of shaping in sails, thangs are a bit different.
D/H the piss out of nearly any sail with a skinny is bad news. Better to rig down sooner. Only sail that I've seen do well with tons of D/H with an RDM was one that had no luff curve from the top to the number 2 batten. That's something beyond the progressive luff curve design that's so popular right now. Worked for that sail alone, methinks since it was targeted for a very specific use.
Had the opp's to try the same sail with lots of masts on a steadyish day several times to validate that across several designers stuff.
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rschnur
Joined: 27 Mar 2003
Posts: 3
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| Posted: Wed Mar 03, 2010 11:57 am Post subject: |
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| jingebritsen wrote: | Yup, we went thru nearly 2 decades of telling most, "try a little more D/H," when asked for performance tips. Now with skinnies and lots of shaping in sails, thangs are a bit different.
D/H the piss out of nearly any sail with a skinny is bad news. Better to rig down sooner. Only sail that I've seen do well with tons of D/H with an RDM was one that had no luff curve from the top to the number 2 batten. That's something beyond the progressive luff curve design that's so popular right now. Worked for that sail alone, methinks since it was targeted for a very specific use. |
My experience using skinnies with a lot of downhaul when powered to overpowered is a bit different. I use skinnies on all my sails from a 340 on a 3.3 up to a 490 on my 8.5. I find that downhauling less than the "medium" manufacturer's setting is useless making the sail too top-heavy to be fun. For flat water, I use the "medium" setting for low wind. medium high to high setting for powered conditions and will go a bit beyond the max downhaul setting to avoid rerigging when the wind really increases. Going beyond the max setting gives acceptable performance. Rigging down would be better at that point for performance, but sometimes I'm lazy and or expecting the wind may drop again or only have a short time left to sail. For waves, I usually use just slightly more d/h than the medium setting, and I'll usually rig down if needed rather than extreme downhaul.
My skinnies are a variety of no limitz, powerex, and ezzy(made by powerex I think). I have three ezzy sails, two aerotechs and a sailworks. All wave sails except the 8.5. Last spring, I used a 5.8 Aerotech Charge on a 430 skinny in a local downwind slalom race run by Britt Viehman at nbwindsurfing.com . The wind was gusting well into the 30's. I rigged to be very overpowered, lots of downhaul and won every race.
Rick |
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jingebritsen
Joined: 21 Aug 2002
Posts: 3371
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| Posted: Wed Mar 03, 2010 4:42 pm Post subject: |
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Some people agree with me, some don't. I've done the head to head, done blind tests, practically. Some folks I sail with pay very little attention to what I hand them, I pump them with an array of telling questions, works nearly every time. No, I don't put words in their mouths.... Call it another form of entertainment, testing and testing thru others' eyes. Makes the flat water blasting a bit more interesting.
When a sail gets a heavy feeling for folks that just want to sail and not bother with the technicals, I'll do some tweaking for them, or hand 'em the same sail with a different mast. Invariably, in my world, the SDM always wins in stability but suffers from being too stiff if not down hauled enough, or taken out under powered. RDM's seldom offer top end stability and nearly always pump softer and whippier. Helps with low end.
SDM's won't allow a sail to flatten as completely as RDM's do. Once all the shape is pulled out of any sail, stability gets pulled out too. The ride suffers too when a RDM is pulled down too much. Like having the suspension set wrong on a mountain bike. Gets twitchy and sticktiony. The sail can't recover to optimal shape as quickly as a fully D/H'ed SDM does.
I got a lot of masts and access to even more. Glad to sail with you on any flat water day and prove it.
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DanWeiss
Joined: 24 Jun 2008
Posts: 2296
Location: Connecticut, USA
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| Posted: Wed Mar 03, 2010 5:16 pm Post subject: |
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| jingebritsen wrote: | Some people agree with me, some don't. I've done the head to head, done blind tests, practically. Some folks I sail with pay very little attention to what I hand them, I pump them with an array of telling questions, works nearly every time. No, I don't put words in their mouths.... Call it another form of entertainment, testing and testing thru others' eyes. Makes the flat water blasting a bit more interesting.
When a sail gets a heavy feeling for folks that just want to sail and not bother with the technicals, I'll do some tweaking for them, or hand 'em the same sail with a different mast. Invariably, in my world, the SDM always wins in stability but suffers from being too stiff if not down hauled enough, or taken out under powered. RDM's seldom offer top end stability and nearly always pump softer and whippier. Helps with low end.
SDM's won't allow a sail to flatten as completely as RDM's do. Once all the shape is pulled out of any sail, stability gets pulled out too. The ride suffers too when a RDM is pulled down too much. Like having the suspension set wrong on a mountain bike. Gets twitchy and sticktiony. The sail can't recover to optimal shape as quickly as a fully D/H'ed SDM does.
I got a lot of masts and access to even more. Glad to sail with you on any flat water day and prove it. |
I totally agree, John, and I sail RDMs exclusively except for racing sails. SDMs are always going to give a sail designed for either only SDMs or both a much better punch and stability on the top end.
Observing this does not, however, speak only to the different effects of RDMs and SDMS because the luff sock of any sail designed to accommodate an SDM mast will always cause the sail to behave as if it had less luff curve when an RDM is used.
I believe some sails are made only for RDMs right from the beginning. In these sails the RDMs should perform ideally, but these dedicated sails might compare very differently to a more traditional sail when put side-by-side.
My general rules for RDMs are these: They often make a sail much easier to handle for smaller sailors. Pumping ease is greatly improved for lighter sailors.
RDMs take a thumping that no SDM mast (Ampro Gray Wave excepted) ever can.
RDMs are easier to handle in transitions as long as sailed with a bit more outhaul.
RDMs are easier for those with smaller hands to handle in the water.
Other than that, RDMs are not all that great. But I continue to use them in my wave sails. Maybe I just like the smaller packaging. |
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iceratz@comcast.net
Joined: 16 Feb 2009
Posts: 346
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| Posted: Wed Mar 03, 2010 7:58 pm Post subject: |
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| DanWeiss wrote: |
Observing this does not, however, speak only to the different effects of RDMs and SDMS because the luff sock of any sail designed to accommodate an SDM mast will always cause the sail to behave as if it had less luff curve when an RDM is used.
I believe some sails are made only for RDMs right from the beginning. In these sails the RDMs should perform ideally, but these dedicated sails might compare very differently to a more traditional sail when put side-by-side. |
This is a critical point to understand about sail cuts.
The SDM and RDM masts will affect the way each is matched to the luff curve, the luff sleeve size and the headcap fit.
Luff curves are very sensitive to the match of each, with improper fits resulting in, noticable increased or reduced draft, as well as batten rotation.
With fixed passive camber inducer designs; (the kind where batten tension does not compress the camber against the mast) the mast diameter becomes critical!
Adjustable active cambers (the kind where the batten tensions & compresses it against the mast) will not be affected as much with differing mast diameters, but may fall into compatability issues, with mast flex/luff curve considerations.
On sails with NO cambers, the perfomance of the sail's shape & stability completely relys on the exact fit of the mast diameter to the luff sleeve fit.
So, 2 things about mast fits:
1) sizes to match sleeve cuts
2)Flex stiffness and ratio to match sail luff curve.
You would be surprised with even a 1/4" of floppy play in a luff sleeve how much performance is compromised.
Use what the designer suggests.
Jeff |
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jingebritsen
Joined: 21 Aug 2002
Posts: 3371
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| Posted: Thu Mar 04, 2010 7:50 am Post subject: |
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Seam shaping and mast sleeve sizing certainly can work together, as well as luff curves and sleeve sizing. Not a designer, just seen lots of sails rigged on different masts and various tensions. Some designs have an intentional amount of sleeve size excesses for allowing a sail to inflate or luff for better transitions and dynamic shape. Sort of an art and science, sail design. Just like rigging and tuning.
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rschnur
Joined: 27 Mar 2003
Posts: 3
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| Posted: Fri Mar 05, 2010 11:17 am Post subject: |
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[quote="DanWeiss"][quote="jingebritsen"]
RDMs take a thumping that no SDM mast (Ampro Gray Wave excepted) ever can.
[quote]
Durability is by far the number one reason I use skinnies. I appreciate the info on the differences in performance between RDMs and SDMs. I've learned a few things. I guess that my point was that even though skinnies may have some performance drawbacks, they aren't dogs either. They will perform well enough in flats and wave, low wind or high. I've broken every other piece of equipment multiple times except for a skinny mast. Probably just jinxed that though. 
Rick |
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isobars
Joined: 12 Dec 1999
Posts: 20935
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| Posted: Fri Mar 05, 2010 1:03 pm Post subject: |
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| rschnur wrote: | | Durability is by far the number one reason I use skinnies. |
Well, sure, of course ... but don't overlook the next 3 reasons, all vital two miles west of Oregon anytime or a mile offshore in the Columbia in a December gale:
2. Durability.
3. Durability.
4. Durability.
Then there's #5: My sails are designed for Skinnies, NoLimitz to be specific. That's their optimal masts. Ditto many brands and models.
#6: Easier to rig.
Mike \m/ |
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Wildblue_
Joined: 12 May 2010
Posts: 6
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| Posted: Sun May 16, 2010 6:27 am Post subject: |
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I agree with Spenny's general point. There's truth the article's generalization though. Here's some more:
A tighter leech, flatter sail (less downhaul more outhaul) for pointing upwind.
A looser leech, baggy sail (more downhaul less outhaul) for downwind speed.
Just ask boat sailors, they adjust both on the fly all the time. Formula, the outhaul is adjusted for every point of sail.
Even a sail with no visible leech looseness will still twist, even at the stage were the battens are still poking the luff sleeve.
Downhaul for the wind speed and adjust outhaul for the general aim of your session, upwind, blasting, reaching, downwinder...ect. |
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