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Old 17th August 2011, 05:51 PM   #1
Floyd
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Cool Objectivity ?? Measurements ???

I know its an old topic and has been moaned about loads but isnt it high time manufacturers got their acts together with the SIMPLE measurements.. I know its hard to determine subjective isues like board performance/gybing characteristics and handling of sails etc etc ..

Went out other day with my 6.5 Maui Pursuit. Its a great sail ;plenty of range, light and stable and quite fast... Mate was on an Ezzy 6.3.. Wind picked up and we decided rather than change down take the lazy option and downhaul more !!! (we`ve all been there)

We both coped but my sail was seriously on limit if not over it at times.. (I was fastest mind)

He looked and insisted (as sailors always do) that he was fine... Was beginning to think I need to get an Ezzy but after session I checked out his sail stats..

Ezzy 6.3 .,(as set) 458 luff.. 190 boom

And mine

Maui Pusuit (as set) 470 luff... 198 boom ..

Thats 12cm on luff and 8cm on boom !!!.

My sail was bigger??? Supposedly by 0.2 m. Its way more than that !!!

Its like buying a 2 litre car; having it measured and it been 1800cc and somebody elses 2200cc !!

Crazy !!!!! And why ?????

Last edited by Floyd; 17th August 2011 at 05:53 PM.
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Old 17th August 2011, 07:10 PM   #2
nakaniko
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I'm not an expert so sorry if things I say are not correct, but...
They seems to be different sails with totally different shapes so this could be the reason. Note that my old Gaastra GTR 6,5 from Barry Spanier has 463 mast and 203 or 205 boom, my newer HSM Speed Demon 6,5 has SAME mast lenght and 193-195 boom. Both 7 battens nocam, imho no relevant difference in power (but meanwhile I changed board), only SD is more direct but also more easy to rig over the FS 4600 (suggested GTR mast...).
Looking at both sails pheraphs Pursuit is a FR-FC nocam (like all my big sail, so less prone to be used owerpowered, but I suppose with more low end. Ezzy has his classic exposed head and comes from the ten years old classic shape of all ezzy wave sails.
But yes, some obiectivity would be appreciated, none is checking as I know the real sail dimension when testing, could it be with an engineer device? I don't know.
But the thing I could be mostly interested is about the REAL weight of a board, so pricy and you don't know if the specs are about a fully naked board (without pads - absurd), or with pads straps and fin (abdusrd on the other side, imho fin is underwater so weight changes a lot). There isn't a common rule. Finally a wet-straps test could be useful, as some board has heavy 4 sponges... Some tests show big differences from declared to real weights.
All imho
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Old 17th August 2011, 11:08 PM   #3
davide
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I noticed that different sailmakers measure sail surface differently many years ago, it might have to do with the fact that a sail is three-dimensional, not flat. But whatever the reason I only buy sails from the same sailmaker effectively solving the problem.
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Old 18th August 2011, 01:27 AM   #4
Floyd
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Agree with what you are saying Nako but even taking (slightly) different plan shape of sails into account there is still no way the two sails mentioned are only 0.2 m different in size !!!

IMO manufacturers build different styles of sails and then "manage" the sizes to accomodate the desired outcome. (Eg Power wave sails are always bigger than normal wave sails) Ezzy are designed to be good in strong winds so they build them small !!!

Davide

Sails are not flat but all sails require a certain amount of material to build them; I`ll guarantee manufacturers know exactly to (high degree of accuracy) how much material goes into the sails ! ie when they pay for materials) Anyhow its still not an argument for not measuring sail area correctly;its not difficult !!

Last edited by Floyd; 18th August 2011 at 01:31 AM.
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Old 18th August 2011, 02:09 AM   #5
BelSkorpio
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The approximate surface area of modern race sails follows a little bit this formula:

Luff size x Real Boom size (you need to add the extra length to the reduced boom size) / 1.4

Floyd, for your sail examples, perhaps not real race sails but I don't care, and I presume no reduced boom length it sums up to:

4.58x1.90/1.4= 6.22 m2
4.70x1.98/1.4= 6.65 m2


So, for sure not 0.2 difference but rather 0.4 difference which is not that far away.
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Old 18th August 2011, 03:52 AM   #6
Floyd
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Like the Formula..

You are right, its not that far off (closer than I`d imagined)but far enough to produce significant differences in power /stability especially at sail`s limits.

Seems a shame that we cant rely on measurements when we are involved in a sport with many things that cant be quantified..

Volumes/Weights/Sail area / mast stiffness and others all seem to produce anomolies... Things which in industry would be specific and measured accurately..

As customers we just accept it ???

Might just buy the Ezzy`s ???!!!
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Old 18th August 2011, 11:28 AM   #7
pxlwz
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I assume, you rigged your pursuit on the correct MS mast to specs (measured from the top of extension ring to bottom of the furthest pulley), you weigh the same as your mate, used the same board and fin as your mate, and are at about the same level as your mate. If any of the above does not apply, that could explain why you felt at the limit, and your buddy did not.
Did you switch boards with your buddy?

I weigh about 160lbs, and always have to over downhaul my TR race sails by at least 1 cm, for them to feel light.
I also have a buddy (about the same weight as me) that has iSonics, and he is always 0.6 to 1 m bigger than me. I could not handle it (Exocet boards), but I plane earlier than him on the smaller sails.
Numbers are just that: A number to start from.
Good luck !

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Old 18th August 2011, 05:38 PM   #8
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Question Original poister spot on !

Cant believe folk would argue against a post which so obviuosly true..

Irrelevant to differences in rigging;skills;conditions ;fins the two sails mentioned are clearly not correctly measured in their area...(or one of them isnt.)

And Davide`s point is also irrelevant.. So what if you only use one manufacturer that does not make it ok to measure area wrongly and besides points made apply within a manufacturer. (Eg compare NP Search and Combats) NP obviously do not use same process for arriving at area for their different ranges..

Weights are invariably out.. Weigh your board..

Volumes are always wrong/out/adjusted.

Compare stiffness of a Tush C45 with a Tush 100%.. Both same IMCS rating !! No way are they same stiffness !

Compare an RDM with an SDM of equal IMCS... Loads different..

Manufacturers print what suits them on specs.. (Many sails dont even rig to spec written on them !!)

Measure your boom ..

Mine says 160 - 220 on it... Its 163 to 223.. Not much I know but why ??? Bought it thinking it would be fine for a sail needing 158cm... Thats 1cm short and boom 3 long; Gap of 4cm !!! Sails fine but it just shouldn`t happen !!!

Or perhaps I cant use a tape measure !!!
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Old 18th August 2011, 10:35 PM   #9
davide
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Quote:
Originally Posted by BelSkorpio View Post
Davide

Sails are not flat but all sails require a certain amount of material to build them; I`ll guarantee manufacturers know exactly to (high degree of accuracy) how much material goes into the sails ! ie when they pay for materials) Anyhow its still not an argument for not measuring sail area correctly;its not difficult !!
Oh yes, I agree, but what I was hinting at is that "we users" cannot really measure the surface of a sail by simply considering its luff/boom dimensions.
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Old 19th August 2011, 11:28 AM   #10
pxlwz
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Wink Mauisails measured the sail

Floyd,

According to Mauisails (the remeasured the sail), it is 6.52m

You can check their forum.

I have to give it to you: Feeling, that the sail is .02 meter bigger, than it should be:
I am impressed!

Pxlwz
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