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blaze720
Really should get out more Joined: 28 Sep 05 Location: United Kingdom Online Status: Offline Posts: 1635 |
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Topic: Sail Sizes Posted: 22 Oct 09 at 4:07pm |
This was touched on in one of the threads recently - Are the claimed sizes reflected in the 'alleged' actual sizes as calculated by the software packages used by the major sailmakers ?.
The reason for this is that we have been working on the Halo rig. On North's package the latest itteration is 11.59m (and Hyde's latest development is a tad larger) and this might suggest that Halo was particularly large. The Blaze is thought by some to have a large sail and that proves to be nearly 10.4m apparently. However it is natural for some arond any club to lay one sail on top of another and make comment. They did this locally when several Phantom ones were laid over a Blaze main. They have very different outlines but by eye the Phant ones did look larger than a Blaze one - yet barside opinion is that it is only 9.75m - ie a fair bit smaller than the Blaze and that was my own impression previously as well The North package puts it the Phant one at a calculated 11.24m - so on a relative basis at least it is actually nearer to Halo than it is to Blaze. I was not sure about this except as a relative measure so also asked Mike Lennon of Hyde what his view was - he confirmed that the Phantom was over 11.0m on their package as well. We have no axe to grind either way frankly - we are just sizing and developing our own sails to do a particular job and not too worried what any package might say or the size of rigs in any other class. But it does suggest that Halo is hardly carrying a monster rig. It is tall for efficiency of course but it does have 2.5m wide wings to deal with it - and it works wonderfully ! So any other views on sail 'measurement' ? Mike L. |
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Steve411
Really should get out more Joined: 09 Sep 08 Location: Cheddar, Somerset, England Online Status: Offline Posts: 705 |
Post Options Quote Reply Posted: 22 Oct 09 at 4:33pm |
Interesting thread. I always wondered why the Phantom took weight better then an RS300 when the 300 main at 10m2 was supposedly bigger then the Phantom at 9.75. Now I know why (+ hull shapes and widths as well, obviously).
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G.R.F.
Really should get out more Joined: 10 Aug 08 Location: United Kingdom Online Status: Offline Posts: 4028 |
Post Options Quote Reply Posted: 22 Oct 09 at 5:04pm |
Obviously the laying one over the other in the boat park routine doesn't
take into account the depth of the foil and the Phantom has a deep belly, more so than the Blaze. It also from my very casual observation (My Pal has a Phantom)seems to have a tighter leech than the Blaze (given my Blaze is kitted with Elvstrom sails that someone told me were pants anyway). Now also it has been my observation of the more modern Dinghy sails which by their very nature are for the most part too big for humans to handle above force three, so seem to be cut with shallower foils and large amounts of negative luff than say a few years back this has the effect of a smaller actual area over a given plan shape and of course the more twist off up top once the wind puffs. Having said all that my experience has been limited to the Alto, Blaze, Musto, Phantom, L&V3000 and the RS600 which to me seemed the most tuneable of all the dinghy sails I've studied. Funny I was chatting away to one of the young 49er squad at Weymouth about sails, luff curve and mast bends since they all seemed to have astonishingly different Mast Bends, which he claimed seemed to make no difference at all to their performance. Now either he hasn't got a clue, or he thought telling me anything would just go straight over my head and couldn't be asked, or they have a series production issue with 49er masts.. But and I note the RS100 is at least dealing with it. In my world you dont make a sail until the mast bend is a given. I realise back in the day things were different, but now with the understanding gained thanks to us in windsurf world, the relationship between the mast and the luff of the sail are so key to any design, it surprises me how loose this arrangement seems to be in some classes. Edited by G.R.F. |
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jeffers
Really should get out more Joined: 29 Mar 04 Location: United Kingdom Online Status: Offline Posts: 3048 |
Post Options Quote Reply Posted: 22 Oct 09 at 5:22pm |
I think what we need to consider here is the difference between 'measured' and 'unmeasured' (or unmeasurable) sail area. A Phantom's 'measured' area is officialy 9.75 sq m. Now take in to account areas of the sail which may come outside of the given measurement criteria (such as depth of cut, loose foot, etc..) and it would be quite easy to believe that the actual sq m of cloth required for the sail is much higher.... The Blaze sails (because they are OD) do not have to be measured after manufacture to ensure they conform to the class rules. This is an interesting point though. I think someone quoted in another thread that a Standard Laser rig is acutally more like 7.9 sq m. Would be internesting to know what the 8.1 sail actually comes out as (might have to pick Mr Rooster's brain for that). Just my 2p..... |
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Paul
---------------------- D-Zero GBR 74 |
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iansmithofotley
Far too distracted from work Joined: 16 Mar 04 Location: Otley, West Yorkshire Online Status: Offline Posts: 209 |
Post Options Quote Reply Posted: 22 Oct 09 at 7:48pm |
Hi Paul,
Funnily enough, I can’t find anywhere in the Phantom’s Class measurement forms, for the sail, or spars, that states that the sail area should not exceed 9.75 sq. mtrs. However, this is the sail area quoted in most publications. What the rules do say is that the maximum distance between the two measuring bands on the mast should not exceed 5626mm, and from the aft of the mast to the outer boom band should not exceed 2820mm. Keeping things simple, imagining a simple triangle and the area of it (base times height divided by two) gives a figure of 7.93 sq.mtrs. Obviously luff curve, foot drop, roach and sail shape has to be included on top of that figure but I would be surprised if it all adds up to more than the approximate 1.8 sq. mtrs difference. I have no idea how these things (outside the basic triangle) can be measured. It would be interesting to know where the figure of 9.75 sq. mtrs originated and why. Ian (Yorkshire Dales SC.) Edited by iansmithofotley |
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blaze720
Really should get out more Joined: 28 Sep 05 Location: United Kingdom Online Status: Offline Posts: 1635 |
Post Options Quote Reply Posted: 23 Oct 09 at 12:13am |
From memory it was based on a Fireball main.... What is the 'sailmakers take' on that today and what does the Fireball main 'measure' today. Has it's 'offspring' grown over time then ?
The key thing is to compare class sails on a like for like basis surely - the relative differences being more interesting than the absolute areas quoted perhaps. So a Phantom sail is in fact 8.17% larger than a Blaze one and a Halo one is 5.78% larger than the Phant one in reality. Should not be too tough for the larger helms as is being proved ! Mike L. |
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jeffers
Really should get out more Joined: 29 Mar 04 Location: United Kingdom Online Status: Offline Posts: 3048 |
Post Options Quote Reply Posted: 23 Oct 09 at 7:51am |
Hi Ian, I think you have hit the nail on the head there mate! There are things that cannot be measured when it comes to sails because they are not designed to be a flat triangle (which is how I believe the sail measuring system works). I did hear a rumour some time back that one of the ways to measure a Phantom main was to lay it over Simon Childs main, as long at it was no bigger it measured (this could be bar speak but it did come from a Phantom sailor)! Other classes have much more involved measurements that make you fold the sail and take various measurements but that the end of the day you are still going to come up against the same issue. Perhaps the classes who measure sails whould bring in a rule that you should not be allowed to use more than x sq m of sailcloth...... |
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Paul
---------------------- D-Zero GBR 74 |
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JimC
Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6649 |
Post Options Quote Reply Posted: 23 Oct 09 at 8:48am |
There's a reasonable and repeatable method of measuring sail area already established. The IYRU (as was) designed in many years ago and its used by at least some of the development classes, one and two hulled. It seems awfully complicated, but in practice its straightforward enough when you've done two or three, especially if you have a spreadsheetto feed the numbers into. With square headed sails you have to do a little tweaking, which is allowed for in the full rule set but this section as listed is all you need for things like Phantoms.
Here you are...
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Scooby_simon
Really should get out more Joined: 02 Apr 04 Location: United Kingdom Online Status: Offline Posts: 2415 |
Post Options Quote Reply Posted: 23 Oct 09 at 11:26am |
SCHRS and most Formula Cat classes use the ISAF model.
Main Sail MeasurementsCM - Area of Main Sail + Mast + Boom
* intermediate calculation if other conditions apply
http://www.schrs.com/measurements.php Works well for us!
Edited by Scooby_simon |
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Guest
Newbie Joined: 21 May 04 Location: United Kingdom Online Status: Offline Posts: 0 |
Post Options Quote Reply Posted: 23 Oct 09 at 11:38am |
Funny that a metric in which people put so much faith can have such variance. I suggest there is a similar issue with manufaturers claimed hull weights ... There is often a significal difference between what it says on the marketing materials & the reality of what the boat weighs. I have always weighed my new boats and one or two showed up quite different to my expectations based on the marketing materials only to be told "they all weigh that ..." http://www.mustoskiff.com/sub-pages/weight-breakdown.htm But as an ISAF class all boat got weighed at the Worlds and everyone was happy so Ovis are making very consistant boats. Edited by Guest#260 |
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