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Cunningham #289028
12/17/18 10:02 AM
12/17/18 10:02 AM
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Leo Ambtman Offline OP
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I am sailing a Tornado catamaran and have checked by GPS that sailing upwind it is useless to use any cuningham at any windforce (except maybe force 6 and above but than you are in surviving mode). As soon as you use downhaul you will sail so much lower that VMG is worse. The cunningham will distort the main sail too much. Any comment?

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Re: Cunningham [Re: Leo Ambtman] #289029
12/17/18 12:11 PM
12/17/18 12:11 PM
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samc99us Offline
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Ummm, what Tornado? Solo or 2 up? Crew weight? How much mast rotation?

My experience is with the modern rigged tornado, carbon rig and square top main sailing at ~430lbs. In Force 5 we were definitely pulling Cunningham. In Force 4 it was getting played. My general experience is you are faster if you are playing the cunni and leaving the mainsheet tight, or an appopriate combination of the two (in the big gusts add cunni and ease on mainsheet). This is the same on the F18 or Inter 20 or F20carbon, basically any modern boat.

If you are finding you have to foot off drastically and need more power then sure, don't pull downhaul. That really depends on the crew weight and base sail shape. If your sail is older it may not respond well to cunnigham. Dacron mains stretch a lot and don't respond the same either.

Last edited by samc99us; 12/18/18 03:21 PM.

Scorpion F18
Re: Cunningham [Re: samc99us] #289030
12/17/18 01:39 PM
12/17/18 01:39 PM
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Hi Leo,
What does your race results show when not using cunningham? Do you have some photos of how your rig and sail looks in different wind conditions without cunningham used. This makes me really curious.

Last edited by reVintage; 12/17/18 01:44 PM.

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Re: Cunningham [Re: Leo Ambtman] #289031
12/18/18 12:44 AM
12/18/18 12:44 AM
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Long Beach, California
John Williams Offline
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i'm not a tornado sailor, but i have found the downhaul or cunningham to be a critical first adjustment to keep a catamaran in trim while racing. if the windward hull is popping or flying too high, you're just not making best speed... feathering up or travelling down are grosser adjustments that rob you of that fast-forward mode, in my experience. as crew, i give a touch of cunningham to help the skipper maintain heading, and it helps both of us if i'm not sawing through two feet of mainsheet every puff. once we've hit the bottom of the cunningham setting, it is time to wind up the diamond wires between races.

sam, how are you easing cunningham and main at the same time? i use both hands on the main, snatch a quick pull or ease on cunningham as needed, and right back to main trim.


John Williams

- The harder you practice, the luckier you get -
Gary Player, pro golfer

After watching Lionel Messi play, I realize I need to sail harder.
Re: Cunningham [Re: Leo Ambtman] #289032
12/18/18 11:18 AM
12/18/18 11:18 AM
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Leo Ambtman Offline OP
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It is a Tornado so we have good leverage. But as soon as you pull the downhaul the draft of the sail goes forward and the top bends open. This causes more induced drag. The shape of the sail is no longer optimal. The GPS shows the results. The big problem is that as soon as the gust is over you tend to sail lower to keep the windward hull up. I think that using downhaul gives the same result as opening the traveller a little bit. Still sailing somewhat lower upwind. A better solution might be more mastbend by more diamond tension. But than you loose speed and depth downwind.

Re: Cunningham [Re: Leo Ambtman] #289033
12/18/18 03:46 PM
12/18/18 03:46 PM
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samc99us Offline
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Leo,

Did you read my questions to yours above? Are we talking about the classically rigged Tornado or the modern rigged? They are pretty different beasts from what I understand, I've only sailed the modern one. Fitting out a classic T or aluminum rigged T with the modern sails and spinnaker is a very good way to get a fast boat, if you have a stiff set of hulls. Racing an aluminum masted but sports rig T vs. us in the all carbon wonder ship wasn't that different in terms of speed. Sailor ability and tactics made more of a difference.

You may need to rotate the rig at the same time as you pull on more downhaul. There is a good explanation of this by Andrew Landenberger here and copied over for your reference: https://usaca.info/landenberger-tuning-tips-mast-setup/

"The typical example is that with increasing wind the sailor will pull the Cunningham hard but not adjust the mast rotation to go with it. The effect of the Cunningham is flattening the sail, but more in the top. This allows the leech to open. The boat may feel ok but often the leech is to open and you can’t point high enough. This setup can be good in big waves but on flat water the sailor would like to have the leech standing much straighter so they should rotate the mast further back. If you go back to our original points you can see that the mast becomes stiffer in the top and can bend more in the bottom. This is therefore powering up the top and flattening the bottom of the sail. With the Cunningham pressure you can sheet on hard and point high with good speed."

Another good reference for mast tuning is Stevie Brewin: https://usaca.info/brewin-sail-tuning-care-2-2018/

There are some good Tornado tuning guides around, to make sure you are at least within nominal parameters: https://www.youtube.com/watch?v=NkQ9uPykaLM
http://www.tornado-class.org/useful-info/tuning-guide/

Anyway, my take on your specific situation is you don't have a very good downhaul setup. You should be able to release the downhaul as soon as the gust is over or even a little before to avoid steering down too far. In the opposite situation, you should be able to quickly pull it on! We run 16:1 on the F18 and lately are running 32:1 downhauls on the A-Cat to aide with this in breeze. The crew has to be attentive on this trim setting especially in gusty conditions!

John,

I switched to a 12:1 mainsheet this year, it was 100% necessary with the boomless DS sail on the F18 but switching back to boomless it is still very nice as in up to 15kts of breeze I can do a good deal of sheeting with one hand, freeing up the other for other tasks such as downhaul. For many years I was told 12:1 wasn't necessary and resulted in a lot of extra mainsheet. Well, after using it, I couldn't disagree more as from a crewing perspective it makes a long day on the water that much easier and by day 5 of a World Championship you really come to appreciate the little things!! Anyway, releasing the downhaul with one hand is very possible, easier with the Spinlock cleats but my last two batches haven't held with 4mm downhaul line so for the moment I'm avoiding them. Once the downhaul is off you quickly have two hands to play the main if one hand isn't enough.

In tricky conditions/big breeze the helm plays the downhaul in conjunction with the crew working mainsheet trim. We use a French rigged downhaul copied from the Nacra 17. This is rigged from the mast aft of the daggerboard to a shock block then back forward and inside the beam. We went to this from the more conventional setup (mast->turning block on crews trap->forward beam) as on the new boat (eXploder Scorpion) the daggerboard moved forward a good bit and when the helm was playing the cunni the line was digging into the leading edge of the raised weather board.

Last edited by samc99us; 12/18/18 03:51 PM.

Scorpion F18
Re: Cunningham [Re: samc99us] #289034
12/19/18 03:51 PM
12/19/18 03:51 PM
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Leo Ambtman Offline OP
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An interesting article of Landeberger but rather confusing. As far as I understand he says: pulling cunningham is ok, but you need to rotate the mast more backwards to point high with good speed. Somewhat later he says with stronger wind people pull the cunningham and rotate the mast back in. This is not good as the sail will have a lot of twist. Rather contrary to the first statement.

In my opinion it is better to be overpowered so you have room to play the mainsheet and steer a bit higher. After the gust you are in optimal trim.

Playing the cunningham does not work. Loosening the cunningham will not work unless you give mainsheet. The end result is a worse vmg.

Re: Cunningham [Re: Leo Ambtman] #289035
12/19/18 05:06 PM
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samc99us Offline
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Well Leo, I can assure you that on a modern Tornado or any modern boat with Cunningham playing it is critical to upwind speed. You can check my race results if you don't believe me...

That being said I still don't know if you have a classic T or a modern T. How the rig behaves is also pretty critical as the modern rigs are stiff side to side and more flexible fore and aft so respond more effectively to cunnigham.

I can see how Landenbergers article is confusing. I would read it twice, but I think the key is basically to rotate the mast between the shroud and rear beam when you start pulling cunnigham on. Cunnigham moves draft forward, flattens the sail overall and increases twist. Mast rotation also controls sail twist, so the two need to be worked together to get an optimum trim setting.

On the water we have found the following:

1) Trimming the mast rotation using the rotation trim telltales a foot or so above the spreaders and a few inches aft of the luff is pretty good. Often you can let the mast float and get reasonable performance, but upwind that isn't always the case.
2) Sometimes you need more diamond wire tension, even without maxing out downhaul. In lighter stuff this isn't the case and can hurt downwind, but in single and double trap conditions where you are thinking about downhaul, you probably should be thinking about diamond wire tension as well.
3) There are modes where you can get the top to blade out instead of twist off (combination of rotation and downhaul) which can be really fast in certain conditions.

Its all time on the water and tuning next to other boats and/or with a coach boat. GPS data helps but doesn't necessarily show the complete picture.


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Re: Cunningham [Re: Leo Ambtman] #289036
12/19/18 05:08 PM
12/19/18 05:08 PM
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samc99us Offline
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You may also want to read this thread, some top T sailors chiming in with their experience: https://www.catsailor.com/forum/ubbthreads.php/topics/65187/re-mast-rotation#Post65187


Scorpion F18
Re: Cunningham [Re: samc99us] #289037
12/20/18 06:11 AM
12/20/18 06:11 AM
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Leo Ambtman Offline OP
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I have a modern Tornado with a carbon mast for a long time. I do not agree that mastrotation has any effect on sail twist. It opens the slot and that is ok in a strong wind. That may be the reason better not to use the traveller as this closes the slot. Twist is not good for pointing because of induced drag. More diamond tension flattens the sail but does not open the top. That might be a good option in a strong wind, but using the cunningham causes twist. Of course this depowers the sail, but the same happens with loosening the main. In the latter case you have the option to power up to the max after the gust. Playing the cunningham does not work properly as the front of the sail will not move up.

I sail a lot of regattas so I know what works. Testing by GPS proofs even more as in a regatta there are too many disturbing elements (different boat types, etc.). To me it looks there is a maximum speed when sailing upwind. The only thing that matters is your course.

The thread applies to sail trim when sailing downwind.

Re: Cunningham [Re: Leo Ambtman] #289038
12/20/18 08:56 AM
12/20/18 08:56 AM
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samc99us Offline
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Leo,

There are details and notes on sail trim that apply to upwind sailing as well in that thread, specifically how mast rotation works. It is a critical adjustment on a racing boat which you probably know, but the T doesn't have a wing mast so its less sensitive to this than the F18, F16 or A-Cat.

If your sail isn't moving after releasing the cunnigham, you may want to try to lubricate the bottom of the sail track.

Have you taken a look at your mainsail trim from a coach boat or at the very least on land with different cunnigham tensions and mast rotation angles? We played with this plus board height adjustments and found an extra 1kt average, 2 kts burst speed at the same upwind angle as before. I won't share exactly what are settings are for this mode as they are confidential and mostly wouldn't apply to your case as the Tornado boards are much smaller than the F18 boards and are somewhat limiting upwind.

Personally I would take a look at your spreader rake as well, Brewin has some good notes on this. I suspect your spreader rake may be too far forward if you are getting a lot of twist, or the opposite if not getting enough: From there (baseline spreader rake), if you move your spreaders back it will put more pre-bend in the bottom off the mast and start the bending lower down the mast. This will flatten the lower part of the sail and move the twist of the sail down lower. Moving the spreaders forward will reduce the pre-bend in the mast and will tighten the lower leech; this will force the sail to twist up higher, earlier. Normally if I have height upwind but want more speed, it is time to rake the spreaders back. If you are low and fast then you will gain height by moving the spreaders forward.

One interesting note is I use almost as much cunnigham in light air as in lots of breeze, in order to force the leech to open. This allows us to run increased mainsheet for additional height at the same speed upwind. Its sensitive as at about 7-8 kts it has to come off completely (often requires a mainsheet ease to get the wrinkles back into the sail), then as the breeze builds closer to 15 kts we end up back near max cunnigham.

Most of my notes are from F18 and A-Cat sailing as my T time is limited to about 4 days. On the T we were running Ullman gear and sailing over 400 lbs so didn't pull cunnigham until approximately 17 kts of breeze, but there it allows you to keep a nice upwind and scoot forward in the gusts rather than keep flying the hull. The other trick I've found in practice is you want enough cunnigham so you are playing with about 1' of mainsheet; if you keep making bigger eases or feel you need to drop the traveller then you need more cunnigham, and if that is already maxed more diamond tension. On the F18 we adjust the diamonds between races if the conditions have changed and I have marks on the mast for this.

Last edited by samc99us; 12/20/18 09:10 AM.

Scorpion F18
Re: Cunningham [Re: samc99us] #289039
12/20/18 10:57 AM
12/20/18 10:57 AM
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Leo Ambtman Offline OP
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Useful information, but known to me. If there is no wind and on land you can pull the cunningham and see how the top of the main opens. You also see that the tension in the mainsheet goes off. So far so good. But this twist is no good. See the books of Marchaj and of Bethwaite (High performance sailing). A flatter sail in a strong wind is better, but still twist is not good for pointing. Also the wind is not strong all the time . It comes with gusts. What after the gust. You may be underpowered. Loosening cunningham has no effect unless you drop mainsheet. Mastrotation on the T can open the slot for sure. I think your experiende with the T is not enough. Because of the relatively small boards it is easy to loose height. Maybe that is why I have a different view. Also the T can have a lot of wind before really overpowered.

Re: Cunningham [Re: Leo Ambtman] #289040
12/20/18 05:26 PM
12/20/18 05:26 PM
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Memphis, Tennessee
Damon Linkous Offline

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Originally Posted by Leo Ambtman
sailing upwind it is useless to use any cuningham at any windforce.... any comment?


Nice discussion!

Leo, on your original statement, could you define what you mean by "any cuningham"? How tight do you keep the downhaul upwind on your Tornado?

Re: Cunningham [Re: Leo Ambtman] #289041
12/22/18 12:39 PM
12/22/18 12:39 PM
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No cunningham at all. Even with windforce 5. After the gust you get at most windforce 4. For a Tornado easy to handle. More wind: more mastrotation to open the slot. Still more wind: go on shore as it is no fun any longer.

Re: Cunningham [Re: Leo Ambtman] #289047
12/31/18 03:31 PM
12/31/18 03:31 PM
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samc99us Offline
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Hey Leo,

Perhaps you can ask Konstantin Trigonis at the next Tornado worlds? What did Xander Pols have to say on the subject back when you did the Heineken Regatta in 2002?

My experience with the T probably isn't enough but the boat is not dissimilar to others I have hundreds of hours on, all of which including the T have a cunnigham that makes a big difference in your ability to sail the boat in big breeze and even in light air. Like Mischa I run 50% and on some mains 70% cunnigham in Force 1-2 to get the leech to open up and the sail flowing. Much faster, but to each there own.

https://www.youtube.com/watch?v=3ydpO5aPltk&feature=youtu.be

-Sam


Scorpion F18
Re: Cunningham [Re: Leo Ambtman] #289049
01/03/19 04:50 AM
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Leo Ambtman Offline OP
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Interesting link. I knew already. How do I contact Konstatin Trigonis?

Cunningham may be ok in light air and big breeze, but normally I do not sail above force 5. In light air a little bit of traveller works good.

Re: Cunningham [Re: Leo Ambtman] #289055
01/15/19 05:01 PM
01/15/19 05:01 PM
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One big factor to consider when gauging speed is how old the sails are. I'm assuming you are using a classic T with dacron sails. There is an age of sails where the draft is so far gone that they are more of a drag than a benefit. Yea, they hold air, but they are not very efficient. The main thing you will want to monitor is your VMG to windward. You can go faster, but it may not be productive. In the 90s, I've seen a couple of teams that would benefit upwind by footing. When I was racing P-19s competitively, we removed the cleats off the downhaul and the crew played the downhaul aggressively. A properly played downhaul is golden with dacron sails. With a scrim sail, it will not change much. On my carbon main, I adjust the downhaul about 4" and that is that. When working the downhaul, you must adjust the main sheet as well. I would suggest setting up the boat in light air. Lay underneath the main and pull different levels of downhaul tension. With each level, take a picture from mid-boom to the mast tip. You can print these out and monitor the draft of the sail. It may be that you are not pulling enough downhaul. How much purchase do you have and how much are you pulling?


Cheers...
Scott Tuma
P 18-2 Mod Turbo "FrankenKitty"
Tornado Classic "Fast Furniture"

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