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Old 7th August 2012, 09:48 PM   #1
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Default camber induced question

Hello, I have a question about cams. Let say we have a 5.5 m sail with two cams and a 6.5 m sail without cams. Assuming the wind conditions are exactly the same and unchanging. Which one will give me more speed? power? or control? I understand that many variables can go into answering this question, however, I am just looking for a ball park generalized answer to help me grasp this camber induced thing. Thanks, Take Care
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Old 8th August 2012, 01:30 AM   #2
Roger
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Still too many variables......
Sailor size/weight....?
Windspeed more suitable for a 5.5 m2 or a 6.5m2......?
Board width........
Surface conditions....different in 5.5 m2 conditions than in 6.5 conditions....which will also
affect board width/type.
Camber inducers simply add shape and stability to a really well tuned sail.
If the sail is too large or too small for the conditions camber inducers will be more helpful
in maintaining the optimum shape when overpowered on the "too large" sail.
More speed..... if the sail is well tuned and the correct size (m2) for the sailor's weight the cambers
would tend to be a little faster.
Not well tuned, wrong size for conditions or sailor weight... not so much!
More power.... depends if it's on the low end, or the top end.
The added shape of camber inducers can add power on the low end, but the downside is that the
inducers also create additional drag in up and down gusty winds when the wind is ebbing.
Well tuned RAF free race sails can provide similar low wind power... in fact sometimes better low wind power that multi-cambered race sails.
If not well tuned....not so much.
More control..... absolutely.... camber inducers add stabiltiy to the foils shape and increase the range of use substantially in fully powered to overpowered conditions.
If you are racing....slalom racing...etc. camber induced sails are what it takes to get to the front of the fleet in most cases.
If you are free riding...cambers can be good, but the rig will be heavier, and rigging will be more difficult/complex when compared to a non-cambered RAF sail
Roger

Last edited by Roger; 8th August 2012 at 04:51 AM.
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Old 8th August 2012, 05:30 PM   #3
Ken
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Roger is right, but here is a simplified view assuming a skilled sailor (75-80 kg) on a 105 liter board in 20-25 knots on flat water.

Power - 6.5 (it's bigger than the 5.5)
Faster - 6.5 (if you can maintain control)
Control - 5.5 (it's smaller and has cams)

If both sails were the same size then it's different

Power - about equal
Faster - cambered
Control - cambered

With that said, I have non-cam sails from 4.0 - 6.0 and cammed race sails from 6.6 - 11.0.

For me, the non cam sails on a bump and jump board are more fun than the larger sails on slalom, and formula boards.

Speed wise (I always carry a GPS), my 5.2 on my bump and jump board has the same top speed as my 6.6 on my slalom board (different wind conditions).
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Old 9th August 2012, 03:16 PM   #4
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Forget the cams, a 1 meter sail difference in exactly the same wind? 5.5 gives you better speed/control in the gusts, 6.5 gives you better power. You would be better off comparing two sails of the same size, or maybe you made a typo on one of the sail sizes? I think Roger & Ken answered the cam issue very nicely.

Other than people who do very high speed sailing or racers who sail in 25+ wind speeds, not very many people will use a 5.5 cambered sail.

Coachg
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Old 9th August 2012, 10:07 PM   #5
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The major difference between a no cam sail and a multi-cambered sail is sail stability when sailing overpowered.

Full-on cambered slalom or formula sails are sailed well- to over-powered. Cambers help a lot to maintain foil stability under load and power within the first 1/3 draft of the sail.

With no cam sails such as wave or freemove sails, draft and foil stability do wander a lot back and forth while being sailed overpowered and you do have to counter such variation with more traction/force with your front or back hands. You will have to fight more with your sail, loose more energy, control and speed. However, a no cam freerace sail such as the Severne NCX is well known to be pretty stable while being sailed overpowered, so it depends on which type of no cam sails we are talking about.

In sum, a cambered sail is used in more wind than a no cam sail of same surface and is more stable, more control-oriented and faster while sailing overpowered. Cambered sails are heavier, pricier, more sensitive to mast requirement (especially bend curve) and require more tuning skills than no cam sails.

So to answer your question about 5.5 versus 6.5 m2 sail surface, board type choice is critical as well. It is always best to match the board type with same sail type, e.g., a wave sail with a wave board or a slalom sail on a speed/slalom board. I'm overpowered with a camber 6.6 sail in 20 knots wind whereas I'm barely well powered with a no cam wave 5.4 sail in same wind.

It's very easy to answer your question about large no cam sail versus small cam sail comparison as following:

1) I have 2 combos that I'm using in the same 12-18 knots wind range.
a) For flat water, I'm using a multi cam Code Red 7.7 m2 sail on an iSonic53 speed board + 30 cm slalom fin.
b) For heavy choppy/wavy water, I'm using a no cam NP RAF Jet 6.9 m2 sail on a Kombat 86 freewave board + 30 cm freeride fin.
The first combo is way faster and powerfull than the second combo, no question. The second combo is just more playfull and easy-going in rough water for bump and jump.

2) So, if I use a cam 6.6 sail with the speed board in 12-18 knots, I'm clearly under to well powered and the second combo is therefore faster and more powerfull most of the time. So, a small cam sail is not always better than a larger no cam sail with the same wind force.

The bottom line and take home message is as follows:

Cam sail are used in more wind and in a wider wind range than no cam sail of same surface.

Cheers !

JM
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