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Old 24th March 2007, 12:10 AM   #1
Floyd
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Default Sail sizes + power

Must have been mentioned before but how can sail measurements (in area) be so different accross different manufacturers. (or even same in same cases)
Eg I have 2 five metre sails. An NP Combat (luff 420;boom 165) and a Gun MC wave (luff 422;boom 175) I do accept all arguments re cut ;shape etc but these two have virtually same plan shape and similar draught. In performance the MC is a lot more powerfull and guess what combat better in strong winds ! (By my calculation these two sails are about 5% different in area !)
I can actually use Combat to change down to !
Why is this done ????!
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Old 24th March 2007, 12:55 AM   #2
Roger
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Default RE: Sail sizes + power

Hi Floyd,
Do you rig the NP Combat and the Gun MC on the same mast?
It could be that one or the other of your sails "likes" the mast you use in both of them better than the other sail.
You've "not accepted" that the cut and panel depth that each sailmaker so painstakingly figures out for each sail to give the rig the desired amount of power and stability, but it's exactly that, and getting the right mast that can make your sailing balanced and effortless, or unbalanced and difficult.
Saying that the "draught is similar" may give you the idea that the power would be similar as well, but is the draft similar throughout the entire sail, top to bottom, with a similar amount of mast induced "twist" or is the more powerful GUN MC a little tighter in the leech whereas the NP Combat is slightly looser in the leech?
Subtle (possibly unmeasureable) difference in where the draft is placed, both fore/aft and higher/lower in the sail can affect the "feel" of the power a great deal.
If you have individual masts, try switching them and see if the power follows the mast or the sail.
Hope this helps,
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Old 24th March 2007, 06:07 PM   #3
Floyd
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Default RE: Sail sizes + power

Hi Roger
Thanks for reply. Yes I agree with all you say.Combat could perhaps work better on NP mast ; I use Tush 45 or Amex 100 (RDM) for either sail. (Both sails better on 100%)
There isn`t a problem with either sail; both great; but for whatever reason (be it cut ; size shape or draft (draught ???)) they can not both be viewed as 5 metre sails.
Is there is something of a marketing ploy going on.???
NP search renowned for power is a big sail for "its size???" the combat renowned for strong wind controlability is small for "its size".
In past we have all moaned about virtual board volumes being quoted(and its now stopped) but we accept it quite readily in sail sizes.
(For comparison within my quiver I multiply boom by luff (in cm) and divide by 1000. This is a very rough and ready (and simplistic) calculation but gives a better guide than the number quoted on the sails. (ie the Combat scores 69; the MC wave 74. This represents about what I would see subjectively as the difference in power rating of the 2 sails. (On same scale my sails score from 54 (for a 3.7) to 123 for an 8.5.
A sails area should be just that.
Good sailing
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Old 24th March 2007, 09:21 PM   #4
Roger
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Default RE: Sail sizes + power

Hi Floyd,
Ahhh... you've added another "dimension" to this discussion.
When you rig both sails on your "Amex 100 RDM" do they feel more
powerful?
My experience with RDM's is that when you use them in a sail that was not specifically designed for an RDM, you get some odd results.
If a sail is designed for a std. dia. mast (vs RDM) the luff sleeve pulls nice and tight (since we are talking small size wave/B&J type sails here) on the SDM as that's the way it was designed.
Put the same sail on an RDM, and you get more draft depth further forward in the sail because there's some extra material in the luff sleeve because it was designed to fit an SDM with a larger circumference.
Also, RDM's and SDM's bend a little differently due to the RDM being more of a "straight tube" where the SDM is a "thin wall tapered tube".
So, some of the difference could be due to the mast diameter and bend characteristics, not just the design of the sail.
Also, in the example you use (NP Search vs NP Combat) it seems you are overlooking the "design intent".
Per the NP web pages:
Combat 5.0 417 luff 168 clew length on a 400 mast
Search 5.0 431 luff 166 clew length on a 430 mast
Per the Gun web pages:
'06 Wave MC 5.0 423 luff 175 clew length (Mast not specified)
So, as you can see from the specs., the NP Search has a signifcantly higher aspect ratio (luff length/boom length) than the Combat.
If we check the aspect ratio of your Gun Wave MC 5.0, it's got a much lower aspect ratio than either the Search or the Combat.
If you read the mfg. hype, the Search is the most powerful in the NP line and designed for heavier sailors that want/need/can handle more power.
The Combat is the "mid range sail" that was designed to "do it all" for all size/weight sailors.
The NP Zone is NP's rig for smaller sailors and ideal conditions.
If we look at the Gun MC wave, with the much lower aspect ratio and longer boom I think it's pretty easy to tell that this would be a more powerful sail, but less maneuver oriented and without the quick "depowering" that the Zone and Combat provide.
So, I think that asking for "standardization" here isn't ever going to work as there are alot more "features" and "mixes of features" to give each type of sail it's own unique "feel" and performance characteritics to suit a vast range of conditions and sailors.
I guess it's necessary to select your sails very carefully (after trying them in your conditions if possible) as simply going by the size, or your estimate of the power available in a particular size, does not result in any consistency.
Hope this helps,
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Old 24th March 2007, 10:00 PM   #5
Floyd
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Default RE: Sail sizes + power

Hi Roger
Again all perfectly correct and very well put/researched.
In many ways we are saying same thing. Sail desugn is extremely complicated and has lots more variables than simply area,,,, but we chose to use area as our "guide". My point being that it is a very unreliable parameter to use to compare sails and becomes even less reliable if measured "inaccurately".
Your arguments re search; Zone; combat (and MC wave are spot on) but neverthe less; lay a 5 combat ontop of a 5 metre search and you will see one of them can not be 5 square metres. Its not rocket science (even if sail designers would like us to believe so) that the bigger is also the most powerful.(in this case)
I have yet to change down to a "bigger" sail when overpowered.
Surely its not much to ask for manufacturers to quote an actual "area" for the sail in question.
We agree that sail area in isolation is of limited use to quantify a sails performance;but an inaccurate measurement only compounds the problem.
Whilst we do not insist on accurate objective measurements iof products (not just in sail area) there is a the possibility of manufacturers manipulatring figures for marketing purposes.
Yes I agree the search is a damned good sail; powrful and stable through its design . It is also powerful because its "big".

As an industry and as consumers we should be insisting on far more objectivity.

Parameters capable of being measured should be done so accurately.

Good sailing.
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Old 24th March 2007, 10:22 PM   #6
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Default RE: Sail sizes + power

Floyd, you are supporting one of the reasons why I try to buy sails from one manufacturer, and when possible, the same sail model. It helps at least get a consistent measurement.

At least with Sailworks, you can trust that measurements are accurate and consistent. On top of that, you know that your mast quiver will work in a consistent manner.
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Old 26th March 2007, 12:24 AM   #7
Floyd
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Default RE: Sail sizes + power

Fair point Roger but it probably means we both think there should be some sort of "industry standard" for measuring area of sails.
Even within the same manufacturer there are discrepencies (accross models)
Checked daughters 4.7 expression against combat 5.0.
If anything exp is bigger ! (in measuring Exp is 1.9% shorter in luff but 1.7% longer in boom) Plan shape identical.Combat slighly higher aspect ratio.
Then again exp is supposed to give good bottom end power; it does again because it measures big.
I`d bet there just isn`t a sail renowned for good bottom end power which measures "small". (ie smaller than quoted area)!
!
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Old 26th March 2007, 02:51 AM   #8
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Default RE: Sail sizes + power

Roger,

Since we are talking about masts, here's one for you. I posted this today on windsurfing.rec. Maybe you can help.

I was bored to tears today so I decided to play around and rig my new
Hucker in the driveway today. Although I own a Backbone mast, I
decided to try it on an old Sailworks Blue label 410cm super epoxy
comp. It may be old but it is bomb proof.

I noticed that the shape was pretty close to when it is rigged on the
Backbone. The main difference is the rig tension. When downhauled,
the epoxy comp bends easier. I could notice it because of the tension
on the downhaul line. My question is, what effects should I expect
when sailing? Will it be a softer mast and thus spill wind easier? Also, will the draft travel because the rig tension is less? Or, am I just wrong?


Peter
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Old 26th March 2007, 12:44 PM   #9
Roger
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Default RE: Sail sizes + power

Hi Peter,
Bruce P. gave you a very detailed explanation of the difference between your older Blue Label 410 Super Comp Epoxy mast ( A 410 EPX actually) and the Backbone 400.
According to Bruce the 400 EPX mast has the exact "spot on" bend characteristics, so you will get very similar shaping, but you won't get the panel tension that you will with the significantly stiffer Backbone
400.
Bruce suggests that your 410 EPX mast will work, but it will be better for lightweight sailors (< 150 lbs.) who do not have the weight to load the mast heavily.
The draft won&#39;t travel, unless you are heavier and can exert the force to bend the mast more.
Interested sailors can find Bruce P.&#39;s answer on rec. windsurfing
Hope this helps,
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Old 26th March 2007, 07:21 PM   #10
o2bnme
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Default RE: Sail sizes + power

Roger, thanks for showing up at the race yesterday. Glad you got out to sail a bit. I have never seen an iSonic 122 before. I&#39;m so used to recognizing the shape of my iS105 and your iS101. I hope to give it a spin with my 8.0 Retro at Windfest.

I was very happy with how the iSonic 105 performed in the races. I have been sailing it for a year now, and still each time I go out I get more comfortable sailing it. Usually, in conditions like Sunday, I finish 2nd or 3rd. This time, I tied for 1st, and on a technicality won the tie!

And to get more on topic...

I was using my Hucker 5.6 with the Backbone 460. That sail was great rigged on a zFree 430 and 460. It is absolutely amazing with the Backbone 460.

I am 5&#39; 10", 145 pounds (178 cm, 65 kg). I think this set up worked better than any other for me.

Erik (6&#39; 2", 190 pounds) took my board/sail for a spin after we finished racing. I&#39;m glad he doesn&#39;t have an iSonic. He&#39;s fast enough on his HyperSonic 105! With the iSonic, he seemed much faster than on the HyperSonic (with an old Gaastra 5.8). He actually remarked that he didn&#39;t think he tapped the full potential of the iSonic... he called it &#39;scary fast.&#39;

What do you think the wind conditions were when you were on the water with us? ~20mph? It felt perfect with my 5.6 the way I had it tuned.
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