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  #11  
Old 07-13-2013
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Re: Twist

Thanks again, Schnool and ShockT.

I can see the mast bend - mainly the top half. I had to measure it when ordering a new main-order mainsail a few years back.

I think I'm basically up-to-speed on the theory now, and need mileage to turn that into practice. Getting the crew "on-board" will require "firm but nuanced" skippering.

There's for sure an art to this as much as a science, and I know to pay attention to both.

Charles
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  #12  
Old 07-14-2013
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Re: Twist

I just wanted to give a general "Thanks" to the contributors of this thread - I've learned a lot by just reading it. Being boatless, it's hard to put the information into practice, but I enjoy learning the theory behind actions.

Also, SHNOOL, your tagline has me looking at C25's now
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  #13  
Old 07-14-2013
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Re: Twist

Resolute... check out Catalina - Capri - 25s International Association for more information on the Capri 25.

The Capri 25 was designed as direct competition to the J/24. It's arguable if Frank was successful with that premise, but it's really intended as a race boat first, and a day sailor second. I however, seem to have managed to turn it into a bit of both. If you can get a back copy (this years) of "Good Ole Boat" magazine... Jan/Feb issue, you'll see a great write-up on the Capri 25 starts page 24.

Plenty of sleeping space in the boat, NO headroom. It's a boat that you can still pick up with a trailer for well under 10k.
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  #14  
Old 07-14-2013
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Re: Twist

Unless you are One Design racing and there is a strong J24 fleet it is a no-brainer! I would take the Capri over the J boat every time!
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  #15  
Old 07-14-2013
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Re: Twist

Well, you can OD race, in one place in the world with the Capri 25.. Wayzata Yacht Club in Missouri. WYC Capri-25 Home/News I can't pull it off even in a long weekend, otherwise I'd try (yep I am little nuts).

So far I am liking how competitive the boat is boat on boat with the S2 7.9, J22, J/24... however, my own abilities.. are not there yet. It's a fun boat though. Maybe I'll give them a run for their money some day
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  #16  
Old 07-15-2013
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Re: Twist

Shnool, the Merit 25 is very similar to the Capri and the J/24. Tuning guides for the Merit say to keep max backstay tension at 1000 lbs or less. I'm using a 24:1 cascade on my boat and it does help. I have the stiffer of the two mast sections (MORC) on my boat.

ctlow - how old are your sails on the 33? looks like it's an old IOR design. You'll need lots of headsails...
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  #17  
Old 07-28-2013
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Re: Twist

Quote:
Originally Posted by Resolute_ZS View Post
I just wanted to give a general "Thanks" to the contributors of this thread - I've learned a lot by just reading it. Being boatless, it's hard to put the information into practice, but I enjoy learning the theory behind actions.

Also, SHNOOL, your tagline has me looking at C25's now
Yes, it has been very helpful, I agree. So I went out a week ago on my own, 33-footer, full main and a #2 in a bit under 10 knots of wind, and got the boat humming, close-hauled. I'm not sure it was fast - in the 5.0 to 5.5 knot range - but all of the ticklers were doing their thing, no backwinding, etc.

And fast does matter! (And bearing off a bit is fast! "If in doubt, let it out!" "Keep 'er full and footin', boys!")

But the problem is to get the crew to do it. With our short-leg races, it really means training them to make many adjustments quickly and with minimal supervision.

I obviously can't race alone because by the time I get the boat all set up I would be at the next mark.

Thanks again to all.

Charles
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  #18  
Old 07-28-2013
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Re: Twist

One thing that I might add is that instead of flagging your mainsail because you are trying to get the boom to the centerline, you might try really blading out the sail as suggested, minimizing twist, put on gobs of mainsheet, but lowering the traveler so the sail has a flatter angle of attack. You will get a little more drive, less drag and more style points. The other thing in a lot of breeze you can move your jib leads slightly aft and add twist to the genoa. This should reduce heeling and weather helm and may let you use your mainsail more effectively.
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  #19  
Old 07-28-2013
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Re: Twist

Quote:
Originally Posted by Jeff_H View Post
... instead of flagging your mainsail because you are trying to get the boom to the centerline, you might try really blading out the sail as suggested, minimizing twist, put on gobs of mainsheet, but lowering the traveler so the sail has a flatter angle of attack. You will get a little more drive, less drag and more style points. The other thing in a lot of breeze you can move your jib leads slightly aft and add twist to the genoa. This should reduce heeling and weather helm and may let you use your mainsail more effectively.
Thanks, Jeff. I've got a few dilemmas in there. Let's say "fairly flat seas but with a bit more wind than 'moderate' for the boat". You're suggesting twist in the foresail but not the main. Did I understand that correctly? The books say that usually both sails will have similar twist.

I'm not sure what "blading out" is. But strangely - and I've come across this in several places and confirmed it with some high-level racing sailors - easing the mainsheet, letting the boom rise and freeing the leech (opening, even though the tack and head are on a shorter line to each other) adds twist but flattens the main. This of course means raising the traveller to restore angle of attack with the boom near centre, whereas you say lower it. I can't quite visualize why that flattens, although I can see how it adds twist. But so be it. It also means having a very tight backstay.

That was one of my original points about "twist": one can flatten and twist at the same time (they say!).

Stronger winds need flatter sails (all other things being equal), and twist. Flatter sails allow more of the sail to be closely aligned with the wind, giving more propulsion and less heel. At least, that's what the books say and how I conceptualize it.

Then there's draft position - we haven't got into that yet.

Can you clarify any of the foregoing?

Thank you.

Charles
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  #20  
Old 07-29-2013
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Re: Twist

Quote:
Originally Posted by ctlow View Post
Thanks, Jeff. I've got a few dilemmas in there. Let's say "fairly flat seas but with a bit more wind than 'moderate' for the boat". You're suggesting twist in the foresail but not the main. Did I understand that correctly? The books say that usually both sails will have similar twist.
Ideally, yes you want to match the twist of each sail and keep the slot consistent, but when you are over-powered you might want to break that rule.
Quote:
I'm not sure what "blading out" is. But strangely - and I've come across this in several places and confirmed it with some high-level racing sailors - easing the mainsheet, letting the boom rise and freeing the leech (opening, even though the tack and head are on a shorter line to each other) adds twist but flattens the main. This of course means raising the traveller to restore angle of attack with the boom near centre, whereas you say lower it. I can't quite visualize why that flattens, although I can see how it adds twist. But so be it. It also means having a very tight backstay.

That was one of my original points about "twist": one can flatten and twist at the same time (they say!).
"blading out" is just racer-speak for flattening your sails as much as you can. That means cranking on the outhaul, the backstay and probably the cunningham. Once the sheet is set in upwind trim, increasing backstay tension will flatten the sail and increase twist because the curve of the bent mast stretches the material between the mast and the leech. At the same time the mast tip comes aft, reducing the distance between the clew and the head, reducing leech tension and therefore increasing twist. That is why you will find that after you make a backstay adjustment, you will need to make a sheet adjustment as well.

Quote:
Stronger winds need flatter sails (all other things being equal), and twist. Flatter sails allow more of the sail to be closely aligned with the wind, giving more propulsion and less heel. At least, that's what the books say and how I conceptualize it.
Twisting the sails off in stronger winds is somewhat of a last resort when you have used all of the other de-powering tools and you are still over powered. High performance fractional rigs are "self-twisting" to a certain extent; when a gust hits the unsupported mast tip will allow the mast to bend and temporarily twist the main off at the top.) Flat sails actually give you less propulsion (and less drag) than fuller sails, but flat is good when you have more wind power than you need. Keep in mind that in this context when I say "full sails" I am not referring to baggy old cruising sails, but good sails that haven't been "bladed"!

Quote:
Then there's draft position - we haven't got into that yet.
Draft position is fairly straight forward. Cunningham and halyard tension are draft controls. Typically you want to start with the draft at about 50%. That gives you a nice smooth rounded entry at the luff. Increasing luff tension pulls the draft further forward which will open up the leech. You will find that as you pull on backstay and bend the mast you will have to pull on cunningham to maintain draft position where it should be, hence, the "blading out" procedure will likely include grabbing a big handful of cunningham too!
Older sails usually need quite a bit of cunningham because as sails age, the draft moves aft. If the draft is too far aft, you end up with a very flat entry on the sail which is very hard to steer to, and at the same time the leech is excessively rounded.

It is difficult to get used to visualizing draft position, which is why many racing sails have "draft stripes" on them as a visual aid. Sighting up the sail from under the boom helps too.
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