The design has progressed a little further again and I must say the performance specs look encouraging. One way to show this is to compare it to a Laser-1 (Laser standard).

Wetted surface area calcs show an interesting picture but before we continue I provide the specs of both boats first :

Used specs :

Laser

Weight skipper 80 kg
weight craft 65 kg
waterline length : 3.81 mtr (overall length 4.08 mtr)
surface area daggerboard : 0.2319 sq. mtr
Full draft : 0.787 mtr

sail area : 7.06 sq. mtr
luff length : 5.13 mtr
mast height : 6.160 mtr

F12

Weight skipper 80 kg
weight craft 65 kg
waterline length : 3.75 mtr
No daggerboards but the hulls present between 1.00 and 1.42 sq mtr. "plate area" against drift. depending whether only one or two hulls are in the water. (a factor 4 to 6 more)

sail area : 7.00 sq. mtr.
luff length : 5.15 mtr
mast height : 5.85 mtr


I had also never realized that the waterline lengths and weights of both boats were so close to eachother. I remind everyone that the rig is very comparable in



Especially note how the rig specs are basically identical. The F12 will have a more modern rig and will create more power while having less drag. But for our purposes here lets assume we just use the Laser-1 rig on the F12, so they have exactly the same engine.

The laser-1 has a total displacement wetted surface area of 2.49 sq. mtr. This will reduce when the laser-1 goes planing.

The F12 has 2.84 sq. mtr. wetted surface area when flat in the water and 2.00 sq. mtr. when lifting the luff hull clear.

Because everything else as as good as identical this means that the F12 will be about 7% slower in no wind, the same speed when only partially lifting the luff hull and be 12% faster when fully lifting the luff hull. This all assumes the laser has no got onto a plane yet.

If the F12 is allowed to use it own sail design then it will have more power up high and lift the hull sooner then with the standard laser-1 rig. This helps improve its performance in lighter winds.

If the laser goes onto plane, then wetted surface area reduces proportionally with speed. The F12 as it is designed will not be able to do that (Deep V-ed hulls) but it has a far better wapon on its side, width ! I don't exactly know when the laser can be put consistantly into planing, but its design and greater width allow it maintain over 2 times more sail drive then the laser-1, assuming the winds are sufficiently strong. At full throttle the laser-1 has to reduces its wetted surface area to AT LEAST 44% of its non planing state to match the F12 power to drag ratio under these conditions. Probably more because I didn't include the induced drag of the daggerboard in the comparison or the loses due to planing spray etc. Lasers do create a significant wake when planing and that all saps energy (=increased drag). Below 40% is a more accurate estimate. And that is high planing.

More elaborate calculations put the F12 at the same speed as the old planing moth which was found to be 8% faster then the laser-1 over a wide range of conditions. It should be noted that the moth was both lighter and wider and had more sail area then the laser-1. It is shorter in it waterline length but that doesn't make much difference when planing.

Again I remind the reader that these comparison are with the F12 rigged with the laser-1 rig and not with its own more efficient rig. The squaretop head will especially improve light air performance while the large F12 width will keep it controllable in strong winds.

It is my estimate now that this deep V-ed hull F12 will be at least as fast as the laser-1 in all conditions, faster in a good portion of these. The F12 strong point will be upwind beating while the laser will still be a beam and broad reaching waterski.

On the race course the upwind leg will determine the winner and that will be the F12 in no unmistakable terms. The "drive to drag" ratio being twice as large then that of the laser will garantee it.

Put women and young teenagers on the boats (laser radial and laser 4.7) and the F12 will be faster again as it can keep its full size rig without control issues. The 80 kg skipper will be underpowered most of the time while 45-65 kg will be nicely powered up with 7.00 sq. mtr. rig.

I think these preliminary results show the F12 promising as a show case for (racing) catamarans.

Wouter

Wouter,

I like the idea of an interchangable rig. I would be able to swap my rig between one platform and another. Again, I would be happy to get involved in this project on the US side of the pond. So let me know when you are ready.

Tom,




There is another US sailor already involved and I would love to receive more help. I can do everything on my own but it is both quicker and more enjoyable to work on the project with several others. Currently I'm also being helped by a UK sailing enthousiast and I have access to an Australian boat designer. I'm especially thankful that they are willing to take care of some of the less glorious work.

My strong points are designing the concept and the underlaying structure and marketing angles. I'm however without any financial resources or workspace to do much physical testing and prototyping. I won't get more financial breathing room for a while yet.

I would love to make use of your skills (strong points) if you tell me what they are.

Again I really do believe that this concept has merit and I have made the choice of getting it done now or forgot about all together. Mostly because I expect to be totally occupied by other things some 2 years down the road.

Thank you plenty for offering your help, it is highly appreciated.

Wouter