So I picked up a Tornado sail as a cruising sail/less area/easy experiment. When I staked it out to re-measure in the yard, it appeared like the luff has near zero curve to it. I need to repair it first so I can fully stretch it and likely release/ease the bolt rope, but is that normal for a Tornado sail to not have a curve to the luff? It doesn't make sense to me, but I know nothing of Tornados.
Found it odd. My other sail has something like an inch or 2 at it's maximum. The sail, otherwise is in great apparent shape, but need very little work and is mostly the right size and shape with a much smaller roach and 9" smaller foot. I could, relatively easily enough over a weekend remove the bolt rope and re-cut the luff, but, uh.....want to get early input. I sure wish detailed sail measurements were more readily available.
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Chuck C
NACRA 500 Mk2
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Not seeing a lot of luff curve in Tornado sail ????
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Posted: Aug 27, 2020 - 03:16 PM
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Posted: Aug 27, 2020 - 06:24 PM
It's all a matter of how the sail was cut; what mast was it made for, the crew weight, etc. etc. etc.
There's plenty of data out there for sail measurements, just need to check the class rules.
https://www.sailing.org/37473.php -
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Posted: Aug 27, 2020 - 10:46 PM
Indeed, I did drag that up and is why I selected the sail as its very close. The luff isn't given, nor the foot. I'm guessing that is inferred/specified in the mast and boom specs? Forgive my very elementary questions, but it seems to leave a lot out.
More so, I'm curious if a major sail maker would leave out the luff curve or if there's something about Tornados that one isn't required in the sail.
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Chuck C
NACRA 500 Mk2
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Posted: Aug 28, 2020 - 12:28 AM
You should look at the Tornado Measurement Guidebook. There are a lot of mandatory dimensions that must be followed and those are spelled out more clearly in the guide. I've had five or six T mainsails and you could lay two that looked similar on top of each other only to see that they were quite different. I had sails with more or less luff curve, it just meant that the mast needed to be tuned differently for each and that they would be different in how they performed in each condition.
https://www.google.com/ur…aw2PxpxeVkb5y0NY8ztmrazr
Like I mentioned before, the shape of the sail will be dictated by the mast that the sail was cut for (tapered or straight aluminum or carbon) and the sailors who will be using it (light vs. medium vs. heavy). Additionally, the aluminum masts weren't consistent and some teams would buy five or ten masts just to get one that they liked. Further, you could have sails with different cuts for different conditions.
You have to realize that those guys were working to squeeze the last two percent out of the boat and therefore they were MUCH higher performance than anything Hobie ever dreamed to make. As such, they are dramatically more optimized, customized and adjustable than what a normal sailor even realizes.
Why does that sail have a straighter luff? You would literally have to talk to the sailors who had it made and the loft and hope that they still had their notes about it, because that's the only way to know. It was likely made for a specific mast with a specific bend characteristic, for a specific weight team with a certain style/approach to tuning and sailing, for specific conditions. -
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Posted: Aug 28, 2020 - 08:39 AM
Awesome write-up. Thanks a ton; that's why I visit this site so much; it's active and there's a ton of knowledge to be had from good people.
Half a dozen masts??? Wow. That's serious about competition. I'm just wanting a good second cruise sail. As an experiment, I'm planning on repairing it (couple of 1 foot rips), releasing the bolt rope, re-measuring and MAYBE re-cutting the luff. I'll likely try it out first though jut to see what it does stock, for nothing else than reference. Could be it's enough for my needs; not going to race with it and I don't have a lot of guess where to go with the curve on a re-cut, because I've got no idea how/where the belly of the sail is, etc., and maybe maximum full shape is good for so much less sail area. If I had the time, I think I'd love to build my own sail from scratch/computer generated model. Only, I could see it taking like a year...
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Chuck C
NACRA 500 Mk2
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Posted: Aug 28, 2020 - 09:33 AM
My friend and I were measuring luff curves on our Prindle 19 sails just the other day. He had the tack staked down and a ratcheting cargo strap at the head. It was interesting to see the difference in curve when increasing tension which would effectively be a downhaul. We figured you try to get the cloth straight with the ratchet with the least amount of tension to get the luff curve, which was about 1 1/2 inches. But we could get over 3 inches with just a bit of tension.
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Bill Mattson
Prindle 19 "Gelli Bean"
Prindle 19 "Cat's Pajamas"
Nacra 5.2 (Will sail her a bit and let her name herself)
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Posted: Aug 28, 2020 - 09:42 AM
sailrite sells sail kits - precut sails you sew togther
not sure if they have catamaran sails in stock but probably -
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Posted: Aug 28, 2020 - 02:09 PM
I know, but their kit quote for my boat was equal to or very close to what Whirlwind charges. That would be the best way to build one yourself, but the $ doesn't make sense. I'm probably just going to repair and modify my own for now. My local loft was actually open to designing and cutting me out a kit, which is what I'd do if I made me one, just because they're awesome and I believe in supporting local brick-and-mortar where I can. Plus, working with a loft to design to my needs and then assembling would allow me to know and understand a whole lot more. He isn't too interested in building beach cat sails. The dude walked me around his loft, sold me some laminate to patch my jib and gave me some tips, etc. Very eager to share where he could; you could tell he is passionate about his craft.
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Chuck C
NACRA 500 Mk2
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Posted: Aug 28, 2020 - 02:57 PM
i think it was Sam who recently pointed out that most non cat sailmakers are not intune with the needs and variations of beach cats - makes sense - very different platfrom -
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Posted: Sep 01, 2020 - 10:34 PM
I haven't actually made anything with it yet, but sailcad has some pretty neat graphics.
http://www.sailcut.com/ -
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Posted: Sep 02, 2020 - 10:01 AM
I downloaded sailcut, but haven't really messed with it. Might have to give it a try in miniature and maybe make a jib out of cheaper cloth and thread (i.e. disposable) just to see if it works.
Now I just need time... Driving a desk all week stinks. You'd think working on something similar to an island would be great - but it just reminds you you could be sailing... I do get PC time, though, so might need to find a way to make breaks useful...
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Chuck C
NACRA 500 Mk2
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