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GURGLETROUSERS
Joined: 30 Dec 2009 Posts: 2643
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Posted: Tue Nov 11, 2014 4:24 am Post subject: |
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Appreciate your problem ittiandro, but as Dan says, too big a sail on the Bic will 'bog it down' in sub planing conditions. (i.e. it will feel 'sticky', as though it would rather not get up and float.)
As said, if sub planing glide, and lack of arm yanking out (and back) is a prime concern, the Kona will feel less like a wrestling match than the Bic, in light wind bigger sail conditions, because it 'wants' to get going.
Again, as others say, the Kona is a 'charming' do it all single board, but not the best for glide in lighter winds compared to racing boards such as Cats or Phantoms. On balance though, it would seem to be the best bet for your needs, over the Bic, and you can be reasonably sure you won't want to part with it once used to its ways. (And planing performance.) |
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Sailboarder
Joined: 10 Apr 2011 Posts: 656
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Posted: Tue Nov 11, 2014 4:03 pm Post subject: |
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Ittiandro,
I own a K1 and it's the board I use the most. I'm about 95 kg. I use it with sails from 5.2 to 9.5, and it works for the kids with a 2.0 too!
In superlight wind, I use an old 6.0 sail made of Dacron with the original soft and light boom, and modern mast. Super light, and probably as fast as a larger sail. Who cares if you are not racing since you are going slow anyway?
In maybe 10 kts, I will use the K1 9.0. Light sail, huge tuning range, early planing too. As soon as there is enough wind to rely on the harness lines, it feels light even with with aluminium boom and 75% mast.
If I expect to be always planing, I use a Ezzy Lion 2 cam 9.5 that is great and stable with the board. I like it better than K1 in typical gusty winds we have here. From there, I can go down to 7.5 and 6.0. The 5.2 can even be used in comfort in high wind, it the chop is not too bad. (Champlain lake was great).
To accomodate this, fins have to be used:
2.0 = 25 cm wave fin
old 6.0 = whatever fin
5.2 = 28 onshore wave
6.0 = 28 or 40 freeride
7.5 = 40 or 46 freeride
9.0 = 46 freeride
9.5 = 46 freeride
I would eventually like to get a more powerfull fin, maybe 50 or 52.
Dan, what would you suggest exactly?
I'm convinced that for me, the Kona is the best allround board. It's higher volume and lenght are a big benefit. Is it for you Ittiandro? I cannot tell exactly, but if you live in Montreal, I could show it to you and let you try if you want. |
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DanWeiss
Joined: 24 Jun 2008 Posts: 2296 Location: Connecticut, USA
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Posted: Wed Nov 12, 2014 5:01 pm Post subject: |
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Ideal fin size and shape varies a surprising amount on the particular sail used. Generally, a larger sail will produce more mast base pressure and call for a more powerful fin to compensate -unless the mast foot can move back and the board still balance at the desired point of sail.
I tested a 54 cm Tectonics Mirage fin with an older 11.0 FW sail with terrific results found while planing as one might expect. We know the common, stock fin is 48cm but it is swept and not especially stiff. It also can be overpowered by very heavy guys on moderate plane. The Mirage helped plane the board earlier -but obviously the huge sail helped a lot. That combo was very balanced while going upwind in displacement mode, but the centerboard simply was too small for the sail size. Too much leeway in displacement mode upwind, and a ton of rig pull in displacement downwind. The downwind solution was too head up and pump to a plane, taking shallow angles downwind while planing. Doing this lit a fire under the Kona One. Even better performance is available on the CarbOne and it's much larger centerboard and sliding mast track. _________________ Support Your Sport. Join US Windsurfing!
www.USWindsurfing.org |
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ittiandro
Joined: 22 Nov 2009 Posts: 294
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Posted: Thu Nov 13, 2014 7:47 pm Post subject: Why do boards have a maximum sail size limit |
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In connection with my previous posts I keep hearing that boards like mine ( a Bic Core 293) may not support too large a sail and " bog down".( I assume this term means something like stalling..) There is something I don't understand.
Perhaps there are some fine hydrodynamics principles behind the idea that a large sail may become too large ( even in light winds) for a given board's design and stall the board, but the Bic is quite floaty ( 220 lt) and stable. Furthermore, at almost 3 mt length it it approaches a longboard. Why should an 8.5 be too large for it and have it " bog down" even in light winds. ? For sure, from my experience, with anything smaller ( even a 7.5!) the board won't even move!
If there is an engineer or a physics expert among the windsurfers of this forum, I'd love to hear ( in general lay words) the principles behind this idea, because I am a "theory" guy and I always want to know the "whys" of things..
Thanks
Ittiandro
Thanks
Ittiandro |
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jingebritsen
Joined: 21 Aug 2002 Posts: 3371
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Posted: Fri Nov 14, 2014 5:48 am Post subject: |
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bog down is a very apt term. put a very large sail on a fairly small board anf the mast foot pressure one has to use to make the whole kit sailing off the wind is greatly increased. the board and fin will be overwhelmed with a downward feeling. as though the hand of god was pressing the tip of the mast straight down into the water. same feeling B T W, when one does not apply enough down haul. _________________ www.aerotechsails.com
www.exocet-original.com
www.iwindsurf.com
http://www.epicgearusa.com/ |
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Sailboarder
Joined: 10 Apr 2011 Posts: 656
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Posted: Fri Nov 14, 2014 9:06 am Post subject: |
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To expand on jinge's reply. With a sail too large for a board, when the wind pick's up, it's difficult to get on a plane. You feel the extra wind pull, but the nose of the board digs a bit in the water, instead of having the nose go up slightly to allow starting to plane. Lot of pull, not much fun. If you manage to plane, the board will be too flat on the water, creating extra drag yielding slow speed and a lot of pull again.
The tricky thing to understand is that a large sail has a higher COE than a small one. The boom being a pivot point, this gives a good fullcrum to the large sail, and it presses harder down than a small one. A big sail therefore provides more mast foot pressure than a small one.
If you look on Bic site, they seem to state that a 8.5 would be ok. If you have the 40 cm fin, you might want to increase to a 46 (like the OD version). This will allow to plane earlier.
For subplaning, it's a different story. I would not expect the board to bog down with a large sail. However, the extra fun factor of a large sail is limited. In these conditions, a thin long board adds more to the fun factor than a large sail. |
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