The Lightwind-Beast development

March 10, 2017
March 10, 2017 1D Sails
I get many emails on how to make catamarans more effective for lighter winds. We can see many sails which is not so efficient. It has power, but cannot go forward fast. I have seen several cases on different regattas that the boat is flying a hull in really low wind, , but was very very slow. It means it has too much drag.
This whole light wind passion started several years ago, when we bought our Tornado. We have lots of light wind days on Lake Balaton. I have started to think how to pimp her. Now let’s see what was done in the last two years.



The very first choice was the famous Chupacabra code0, which was the “original” one from Qingdao. The next choice was the superflyer code0, which goes to the top of the mast and to the rear crossbeam. This is strictly to max 3kts wind.

Finally I arrived to the mainsail and jib developments two years ago.
First I have made the head bigger, but with the same flying shape as our standard Tornado main. It was very very fast in very small breeze, like 1-3 knots, but as the wind picked up, started to make strange behaviours.  I have played a lot with the batten stiffnesses, but ended up that sail is great for max 8 knots, but ideal is max 6kts. So I moved forward.
The second version was different. Once, it was made of technora membrane. The design was a little changed, bigger luff curve, more additional camber, and different exit angles. I was waiting very much to test this sail, but it happened, before I could try it out, the sail left to the USA. Not exactly for a Tornado, but a 20 foot boat. Luckily I have got many pictures about the sail, so I had the possibility to analyse it.
The third version. I went to radial cut this time. It has two reasons, one, is I wanted to try out that material, and I thought in this case people doesn’t really want to buy it off from my boat right away on the first day. About the shape, some luffcurve changes, slightly different head width to be more easy to handle and a cut down for the head to be flush with the top of the mast. Bigger roach on the leech, trying to balance between the power and as less drag as possible. Finally I used this main a lot. On the first run, it came out that it is a very sensitive sail. Played some with the batten stiffnesses, but turned to be a really good setup. Early hull flying, but still fast. Combined with the new jib, it was awesome.
As each from our own sails, it left to a new owner, now to Chiemsee. In the last days  a sister sail was made, but from technora membrane, to Chiemsee as well.
V4. This version lives only in my SMAR Azure folder. Yet. I haven’t had time to build it, but within short time I have to do it as the season starts. I have reduced the head more, chose the radial cut again, more roach on the leech and a much better lift/drag ratio. I will write about this sail later in a different post.
I was working as much on this sail as on the mainsail. I was searching something different as our current class legal Tornado jibs, but I was not sure what I really want.
V1. I have added more are, positive leach, it was fine, but not the one I was searching for.
V2. Kept the positive leech, 4 battens, a slightly bigger head. It was significantly better than the previous one, and was faster. This sail went to the USA together with the mainsail.
V3. Same as V2 but different luff curve, different shape, and fat head. This was made for the black radial mainsail. This was really fast, especially in choppy conditions, I loved it very much, I thought I was looking for this sail. One day we were heading back to the marina from a nice session, the breeze picked up a little bit, and the negative sides came out. Now I know what I want. This sail landed in Chiemsee as well. Now just leaves a new membrane one there as well.
V4. I put all my knowledge into this sail, I have made it from Cuben Fiber, refined shape, many time on analysis, smaller head and a much manageable leech and head for our hectic wind conditions. We have tried it, and I loved it. I made a swap in the window panel, so the bigger part is afterwards. I was just curious how it feels on water. After some session it travelled to the Netherlands to the new owner.
V5. No it is in SMAR Azure only as well. Now I know it will be the jib of my dreams. We will see. I have kept the all the major characteristics of V4, just refining them, changed panel layout a little, and some movements on the batten positions. I write about this as well in another post.
Downwind(?) sails
We have an awesome Tornado kite design, I have made myself one from cube finer, which was fist like hell. I couldn’t believe the difference to a nylon or a polyester one. As always, it went to a new owner.
For the next I made an upgraded version of the Chupacabra. I have now much different tools for designing that was available in 2007-2008, nice, analytic tools, so I thought it is time to rework the masterpiece. I had some leftovers from a nice polyester material and just made one from the new version. Just to use something on a weekend session. We were just matching up with some F20s, and I couldn’t believed how fast we were downwind with this flat kite. Way, way faster and deeper than the others 4-8kts of wind. Of course the boat handling etc was in that as well, but after I opened my MacBook to look up again what I have done.
Haven’t tried it upwind, for that matter I use the a very flat code0, the superflyer. Perhaps this year I will work on the Chupacabra new generation. We will see. One thing is sure, that the evolution of the downwind sails for the flying boat made me to think on a different way for the “normal” catamaran downwind sails as well).
The Superflyer is great for downwind as well as there is area, but risky as the top of the mast is pretty weak.
As I have built the new sails, I will make a review on them as well.


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