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techno900
Joined: 28 Mar 2001
Posts: 4161
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 Posted: Tue Dec 02, 2014 9:34 am Post subject: |
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andywind said: | Quote: | | Thanks to cgoudie who correctly pointed out that this happens with big sails only -7.0 and up maybe -I think I'm starting to understend what actually happens . I don't remember this happening with my smaller sails, but I also don't remember anything like this when I was using a 8.5 -3 cambered semi racing sail with a 100% carbon and extremely stiff 490 racing mast. I just might have been lucky but I think the mast matters. |
You can be overpowered on ANY sail, all you need is enough wind. If you are powered correctly with a 5.0 in 25 knots and a 35 knot gust hits you, all the "overpowered" symptoms will be there. With correct tuning for modern sails, they tend to stay balanced over a wider wind range, but all will "slam" you with enough wind, and this includes cambered race sails. Larger boards and fins amplify the issue. |
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rigitrite
Joined: 19 Sep 2007
Posts: 520
Location: Kansas City
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| Posted: Tue Dec 02, 2014 11:15 am Post subject: |
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| Quote: | | Let's not be ridiculous please! Fins DO create lift , everybody knows that! |
No need to get mad. This is perhaps a worthy topic for a separate discussion, but no, fins in no way create lift. They're symetrical foils, so forces are always balanced as long as they're not canted (like sailboat rudder). I can come up with a simple diagram to explain if you want, but suffice to say, that if a fin created lift, the back of the board would be trying to swap ends with the front. It would be like spinning out, but in the opposite direction (to windward). Clearly this does not happen.
The sail is the driver for all the unpleasant effects of being overpowered.
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adywind
Joined: 08 Jan 2012
Posts: 665
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| Posted: Tue Dec 02, 2014 11:42 am Post subject: |
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| I agree with you tecno900, if I haven't experienced it wit smaller or racing sails it doesn't mean its not possible, it just means I didn't have strong enough wind. It also may mean that with the shorter masts and less "real estate" of the wave rigs and the stiffer mast of the racing rings and their more stable -cambers supported sails it will be more difficult to happen compared to big freeride rigs with softish masts and no cambers. |
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swchandler
Joined: 08 Nov 1993
Posts: 10588
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| Posted: Tue Dec 02, 2014 1:12 pm Post subject: |
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It wasn't my intention to divert the discussion, but it's important to note that the fin isn't passively along for the ride. For those that don't think that fins don't provide lift, try fully engaging a daggerboard at planing speeds on a fast reach and see how long you can keep the board on the water. While a daggerboard isn't exactly a fin, I've had the same experience with fins in the past, particularly overly stiff ones.
Overall, it's important to recognize that sails, boards and fins all work together. Too much fin can be as unsettling and difficult as too much sail. It's all about matching things up to create a proper balance and a sense of harmony. |
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ghost1
Joined: 11 Mar 2013
Posts: 56
Location: Burlington Ontario, Canada
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| Posted: Tue Dec 02, 2014 9:05 pm Post subject: |
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| jingebritsen wrote: | | could be time to down size. what about trimming your sails with the right tensions on down haul and out haul? are you following the guidelines on the sails? |
I think so. I am cranking the downhaul down as far as I can and getting the sail loose between batton #2 and #3 about half way across the sail. I've had a lot of rigging advice from some of the better sailors where I sail. I've also watched a ton of Ezzy sail tuning videos.
My outhaul is where I seem to do the most manipulation. For the Neil Pryde Fusion 6.7 it says "203cm". I set it to that and pull it right to the end of the boom for low to medium wind settings. So when I start to get overpowered I take it to 205cm. Can I take it to 207 or is that too far?
I've also got my battens tensioned correctly.
I guess I could also drop my boom a bit more too to get more out of the sail. Typically I keep my boom at neck height, so would I drop it to shoulder height? I use 28" lines as well.
But I'd say once I get to 25kt+ I need to drop down sail sizes because I'm totally out of control. |
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isobars
Joined: 12 Dec 1999
Posts: 20935
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| Posted: Tue Dec 02, 2014 9:56 pm Post subject: |
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UM, yeah ... 6.7 @ 25 kts is asking too much for most recreational sailors. Many of us CAN manage that for a few minutes with special techniques, but it sure as hell isn't fun or optimal if not racing other pros for real money in gusty wind. Most of us, including me and many guys 50 pounds heavier, would be very happy with a 4.5 (on 70 liters if they're used to it) when it's blowing 25 kts.
Mike \m/ |
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boardsurfr
Joined: 23 Aug 2001
Posts: 1266
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| Posted: Tue Dec 02, 2014 10:38 pm Post subject: |
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| rigitrite wrote: | | This is perhaps a worthy topic for a separate discussion, but no, fins in no way create lift. |
Ha ha, that's funny! You should have been on my old AHD with a 50 cm fin when the wind picked up and the fin threw me off by raising the windward rail faster than any racing centerboard ever would. Very memorable flight! Or check how one of the top windsurfing fin manufacturers characterizes the nose and tail lift on their fins at http://www.mxrwindsurfing.com/whale/
There's a basic explanation on how fins provide lift at http://www.windsport.com/gear_article?news_id=3. The part about the "over finned" board is actually relevant to this topic. |
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dllee
Joined: 03 Jul 2009
Posts: 5329
Location: East Bay
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| Posted: Tue Dec 02, 2014 10:48 pm Post subject: |
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Overpowered....
Couple years ago, Berkeley Marina, winds 28-46 mph, me waay beyond overpowered with a 4.2 downhauled ragged to the clew, and 78 liter board, Phil McGain rigs his 5.8 TR-8 prototype, goes out on a 50 cm slalom board, and proceeds to make 4 runs looking good.....until the explosion outside on the 5th convinced him he was quite OP'ed. He looked like he was beat up really good, after 8 minutes of windsurfing. |
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jingebritsen
Joined: 21 Aug 2002
Posts: 3371
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