Can we talk about this single control line rule? It seems to me that this will work well upwind, but on initial view it seems we may end up with quite a bit of twist off downwind. If that were correct, this would mean that we are no longer sailing to VMG downwind.

What am I missing? what is your plan?

You are correct.

But while this issue has not been discussed publically yet (except for the traveller setup) as solution is worked out anyway.

There are two versions : one uses a kicking strap (non-adjustable) and the other uses a ram vang (non-adjustable)

These have a use upwind as well. By preventing the mast from bending back too far when the mainsheet is released the sail should tack better in lighter winds. Additionally this limiter prevents the boom from rising beyond a certain level and thus reduces twist when the sail is fully boomed out.

But for most course John is right the F12 will have a traveller system, one that only costs 37 Euro's in DE-LUXE version and 4.5 Euro's in the cheap but effective setup. this will take of most needs All the way up to reaching a little deeper then a beam reach.

It is many more things but I'm not going into detail on this here and now.

But I can assure the readers here that teh basic idea is to give the F12 significantly more performance then the alternatives out there (like the wave) by providing much better sail control. The only limit to this is cost but even the DELUXE version costs less then 200 bucks overall. While providing full control in light, medium and heavy winds with draft control devided in lower halve and top halve and twist control for both the light and heavy winds.

Pretty much the design goal I had was this :



Light winds :

relatively shallow draft in the sail with alot of twist along the leech.

medium winds :

10-15 % draft in the sail with a tight leach. Here the mainsheet mostly controls draft in the sail and very little twist.

heavy winds :

shallow draft in bottom part of sail with almost no draft in the top and a leech that is twisting off. But with the behaviour that releasing mainsheet first increases twist and hardly any draft. If possible releasing the mainsheet should first increase draft then allow the boom to swing out and only in the later stages allow the draft to increase.


I think I got that worked out to a large extend.

Wouter

Is a windsurfing rig still in consideration for the F12? If you take a modern windsurfing rig and pop it into that welded bracket as shown on the land sailor...all the tweaking is done when you rig up the sail at the beach...other than maybe a traveler...and the main sheet what else is there left to do? I am really excited to see what a modern windsurf rig could do on the F12...IMHO the windsurfing rigs (sails/mast/boom) are light years ahead of the sails the catamaran community has in use.

The interplay between the sail cut/mast flex/boom stiffness
makes the windsurf rig feel alive. I would go so far as to say that most boat sailors would wet themselves if there boat had the 1/2 the gust response a well tuned windsurfing rig has. A gust hits and its just pure forward acceleration.

...ask anyone who windsurfs at a near expert level (short board) who is also a cat sailor... they will confirm this.

Regards,
Bob

Hi Wouter

“1- What do windsurfer do when the wind changes in strength?”

They use to have to change sails every 6 mph or so…now you can go out with a top quality sail and hold it down in wind that would have required 3 or 4 sail changes 15 years ago.

“-2- How many suit of sails do windsurfers have to be able to sail whenever they want ?”
I use to have an 8.0/7.0/5.7/5.0/4.5/4.0/3.5/3.0 in the late 80’s that would let me sail from 5mph to 40 mph winds. But the 5.7-3.0 were for surf sailing…where it is much more important to be dialed in with the perfect size. Back then just for recreational flat water it would be more like 8.0 6.0 4.5 Today you could easily hold down a good race 8.0 from drifting conditions to well over 25 MPH wind on flat water and the proper board. Basically all the conditions that catamarans are regularly sailed in.

The cut of the sails and the way they have tweaked and tweaked the sails and sail mast interaction is just amazing.

3- How well does a windsurfer transition from pure upwind work to downwind with high vmg ?

That’s a function of the board shape (rocker/bottom shape/rails) and fin being used as well as the sail itself. Dead down wind is not its fastest point of sail but sailing powered up on a deep broad reach will get you downwind at break neck speeds for sure.

“Sailboat rigs can sometimes have amazing flexibility in flying shapes produced by adjusting a few control lines while racing on the water. I haven't seen surf board rigs do anything like that.”

My Friend Mike Gephardt three…(or was it four?) time Olympic sailboard campaigner (one silver, one bronze) has had adjustable outhaul and downhaul on some of his race boards that I have seen to address just the things you are proposing…

Please don’t take my enthusiasm for windsurfing as a knock on catamaran sailing…I love them both…it just that windsurfers has been so much more open to new development than boat sailors. So to have a chance to take what I feel is a vastly more developed rig and apply it to a catamaran gets me all excited.

One lesson that windsurfing surfing seemed to grasp right away it that everything is interdependent…and although that sail design might not have worked last year, it works great this year because the board is been refined to capitalize on the sails strength or the fins improved which allowed the sails to be cut flatter and still have the power to plan out quick…or that setting on a softer constant curve carbon mast allow the sail to breath with every puff but reset to its static shape much more quickly. Large square head sails with tons of downhaul that allowed sails to triple there designed wind range. Its not that Cat sailors are unaware of this, it just that the windsurfing community has put more a lot more energy into R&D . Every variable affecting every piece of gear was/is on the fast track so that it just keeps getting better and better at an accelerated pace.

On the other hand most Cat sailors seem to put “protecting their investment” over any desire to propel the sport to the next performance level. Every possible improvement is seen as a threat of making their cat obsolete.

Shake loose some of the cobwebs and fire up some cat sailors to consider something beyond the status quo…LOL..push the limits till they squeal like little girls. I can’t wait to see were we end up.

Best Regards,
Bob

I'm not ruling out windsurf rigs and that has been my personal opinion from the beginning.

As the situation stands a windsurf rig can be fitted to the F12. I see no need to forbid it.

Still the designing I've done so far does not enclose optimizing a windsurf style rig. The reasons for this decision are as follows :



-1- Cost limitations

A class 5 mast can be homebuild by an absolute amatuer.


-2- Sail efficiency.

A sailboat rig at this time can have a significantly higher aspect ratio then the windsurf rig.

I'm not sure that the current lower aspect surfer sails can easily be scaled up while retaining their excellent behavior.


-3- A cat is significantly different from a surfboard

In my experience a catamaran has a much lower need for gust response then both skiffs and sailboards. Having the sail respond to a gust while it is not necessary means losing performance. At this time I feel a more conventional catamaran rig is more suited to getting optimal performance over the full range of conditions from light to strong. It not about holding a sail down in all conditions, it is also about getting maximal performance in all of these conditions.


-4- Windsurf sails don't really have a mainsheet system that affects the leech tension.

In affect with a more conventional rig you have one extra tuning control. With f12 you have two more as the traveller setup can be set to windward (something normal cat traveller systems can't do).


-5- I'm personally not experienced in windsurfer sails.

I understand catamaran sails to a large extend and surf sails to a much lesser extend. In effect I do what I know best. Maybe somebody else needs to do the design work involved with F12 windsurfer sails ?



But again these are not reason why the surf rig is disguarded (it is not), they are only reasons why I'm not developping it further as opposed to the class 5 landyacht based rig.

But if anybody else wants to spend some time on this I'll be very interested to hear the results.

Wouter

I am trying to persuade a windsurfing school and a holiday company to test my current boat, which has a biplane windsurfing rig setup, both these companies have experienced dinghy and windsurfing sailors on their staff. The feedback should also apply to F12 windsurfing rig setup. I am hoping to get a better understanding of which sails work best. I will share the results with group.

Gareth