Jerry,

My outhaul could not really be tensioned with Daniel on board, the system I was using then didn't really allow that. Still it was pretty tight. However the lower 1/3 of the sail still had a little draft in it. Middle and top parts where rather flat I can't really remember how flat. I weighted 85 kg then, Daniel was about 60 kg or slightly less and we were double trapping in wind swinging from 15 to 25 knots of wind.

One thing I also tend to do when it is really honking, is derotating my mast till the top of mast falls away to lee and inverts the top 2 to 3 battens. Meaning that the battens bend towards the luff side of the boat. This really depowers the rig and doesn't seem to hurt speed much. Try that on a boat with a different mast ? Point is that there are many things you can do with this rig to depower it. More than you can with a normal rig. Now I just have to find out which is the fastest method of depowering. Although I'm finding out that staying upright in such conditions is by far the best way to a good result no matter which method for depowering you choose. More and more I concentrate on making the boat calm first, choose proper lines and approaches second and fine-tuning third. That is in the really really strong stuff. When things are alot calmer then fine-tuning moves up. Here proper trim can make big differences in boatspeed and therefor in your final placing.

Wouter

Eric, did he say anything about what he was working towards more precisely? Straighter leech, draft distribution or something?

I am asking becouse there are many airfoils with very good L/D ratios, but there are so many variables when it comes to sails that I am wondering what he ment by that. Especially as sails have to adapt to so many different conditions as windstrength and seastate change.

Just curious..

I was asking him for a powerful sail. He said, sure it'll be powerful; but just as important, he said, is to be able to flatten the sail and make it very streamline for maximum speed as the wind picks up. The sail does work well and has been versatile.

The only tangible thing I can see is the mini battens at the top of the sail in betwee the regular batten. He said these prevent any leech flutter and enable the best/most perfect flattening.

hi eric,

the small battens to stabilize the leech flattering inbetween the big battens came up when most sailmakers in the A-class changed to the smoked pentex material, which has more stretch than the kevlar used before. actually the first Landenberger (done by Ashby in Landenbergers loft) did not had these battens and started flattering after the first windy race... so the small battens were an initial repair. the kevlar sails (as well as the dacron brewin sails) did not discover these problems before. in the same time sail shape changed and spreader rake was moved as far as 80mm by some guys... which also takes tension out of the leech, but more in the lower part. so I think it's a combination of both but when you start to have to fix those buttons on the sail yourself (I had one Landenberger with an even softer material requiring 2 small battens between each pair of the long battens) it does not really make you happy...but if such a sail than allows you to be really fast you also don't mind it to much...:-)

Thanks Eric and Dirk.
There is probably more to it (shape selection/draft placement and a carefully designed luff curve), but those small battens are common in windsurfing sails. Sounds like we are adopting more and more technology from windsurfers

What i've been able to find out by milking Greg Goodall and others for all they know is that in overpowerin conditions you are looking for shallow draft with a some twist in the leech in the upper 1/2 or 1/3 of the sail. Shallow draft improved lift the drag ratios, so when your max amount of lift is set by the max righting moment than increasing this ratio will reduce drag and thus make you faster. The twist is there to reduce the drive devellopped in the top of the sail which is trying hardest to push you over but also leads to a disproportionally big drag component because of the tip vortex. By reducing the pressure difference over the top part you both reduce the moment pushing you over as well as the size of this single drag component. But as always there is an optimal point somewhere and both "More" and "Less" maybe be slower. And here the dark art of sailmaking begins.

Wouter

Eric and Wouter,

Thanks for your comments.

Yes Eric, I know flat is fast, especially in high winds, but I still think that too flat is slow. On my monohull dinghy I added a 4:1 outhaul because I thought that would make it easy to fine tune the OH under load while hiking if I needed to and the result of that much purchase is that it's all to easy to make the foot of the sail flat as a pancake (ie, flat with horizontal creases). Now what I was saying is that when the foot of the sail was drum tight, I felt it was too flat and the boat felt slow. By adding some draft (ie, an inch or so from the boom) the boat seemed to heel less and accellerate. I'm not sure but I doubt when you say you want a flat sail you really mean having the foot of the sail drum tight (or do you)?

Wouter - interesting that Goodall's comments included having twist 1/3-1/2 down the sail with narrow draft in overpowered conditions. As I said earlier that is exactly how windsurfing sails are designed. You get a flat sail with twist at the top. The twist does dramatically reduce drag, but I think it has to do with more than tip vortex drag. There's lots of info on that in the windsurfing literature. The ability to get that shape does result both from a combination of the mast stiffnes/bend profile, how the sail is rigged (tensioned), as well as from how the sail is cut. Each person's experience on the best way to trim their boat may vary significantly not only if they have a different mast section but also becuase the cut of their sail will effect how it flattens and what it's drag/lift characteristics are as the mast bends. In windsufing, the stiffness and bend profile of the mast massively effects sail shape as the rig is tensioned and that's obviously true of catamarns as well. Interestingly, whereas windsurfing masts have a fixed stiffness and bend profile one of the things that's so great about the super wing mast is that the stiffness and bend profile are dynamically configurable. I used to think of the super wing mast as softer (in comparison to Hobie or Nacra masts) but after reading your posts Wouter I've concluded that the super wing mast can be stiff or bendy depending on how you rotate it in relation to the apparent wind (spreader rake and diamond wire tension notwithstanding). No need for on the fly adjustable diamond wire tensioners!

Jerry

Hi all!

I know, sportive sailing pics would be better (specially as typhoon talin left us 15-20 knots of breeze) but as a start...

the sail is a brand new F16 sail with a 900 mm square top designed by Andrew Landenberger in close relation to current A-Class sails and after a first test in those windy conditions I am very happy with it. It is easy to trim that the square top opens nicely in the gusts...

actually only two of the boats are constantly sailing, one is still waiting for its owners to return from france and the one covered seems to be jinxed as it has its second owner since the boats arrived who also might be selling it again. anyhow we always have plenty of company, large dragonflys accompany the sailors and the site!

Hi Dirk

Cool you made it back on to the water!
I wish you good winds and waters to enjoy your new craft!

Greetings from Switzerland

hi andi,

yes, at least some sailing again, although I miss racing the A quite a lot... No serious racing here at all yet :-(

Team Ost let me think of Poland ;-)
so you switched to Javelin? Is it a faster boat than the Ventilo was? Can you still use you wided beams? Any Texel ambitions next year?

dirk

Hi Dirk

The Project with my wider beams has died. The reason why, is that the 18HT class in Switzerland and in Italy, really took off.
Plus 30 Boats sold only in this year here in Alinghi-Land. Not all of them are racing, but at the next regatta we expect 20 18HT boats!

Also in Germany, Niels Bunkenburg has designed a new boat for Eagle-Catamarans.
I think that Heiner from Eagle-Cat has already sold plus minus 10 Boats.

My old Ventilo was slow, compared with the Javelin.
Bu the new Ventilo 18HT looks very promising and is designed from Martin Fischer.

Texel ambitions? Of course! We were there this year and will be there next year! Just to much fun!
But I have to admit we didn't made it around the island this year.
We were there a whole week and sailed the Dutch open. On the race day, the surf was to bad for us.
After a first attempt, getting through the surf, we returned to the beach.
Picture

Polen? well allmost.....
the guys west of zurich think that everything east of them, is russian related.

Dirk,

can you send me the original high resolution copies of these 3 foto's. Send them to formula16class(at)hotmail.com . I think I will use one of these for an F16 article in a catamaran book.

Yes, guys you heard it right. After being invited to have an article in a Dutch catsailing magazine, we have received an invitation to be discussed in a new book about catamaran sailing, together with the other formula classes.

I think that our little beach head in china is just a great tangent.

Wouter

wouter, these are the only pics i have.

on sunday we will have the first regatta,

a long distance race with all boats ...

that might bring some nice 4.9/F16 pictures,

if you can wait some more days...

Dirk,

I have some time and I don't believe in rushing to get a good picture

Wouter