Beldar..... I used a beam reach for most of my tests and calculations. While the numbers indicate that it is theoretically possible, the Lateen Sail is not the best design for that purpose.... and if you change to a taller rig, then you've gotten away from that which is essentially Sunfish.

The differences between the Laser and the Sunfish is that the Laser's rig is more efficient at higher boat speeds, while the Sunfish's rig provides it's best power at moderate boat speeds. It's a function of aspect ratio.... the Laser sail has a higher aspect ratio than the Sunfish. A good analogy would be a high RPM engine vs a lower RPM but more torque engine.... both show the same HP, but at different speeds.
Could you safely change the aspect ratio of the sail by adding more sail area to the top with a small sprit and increase available power without changing out the mast?
Obviously those interested in this thread are the adventurous tinkering type and realize that we are talking about putting a v8 in a Geo Metro, enjoy a challenge and just want to see if it can be done.
Don't give up! :)
If you are interested in the 3D model files of the parts I drew up and posted in this forum thread, PM me. It wouldn't take a lot of resources to have someone machine these out of wood on a cnc machine, waterproof them and mount them.
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Here is an alternative idea to having the parts machined.
I have access to a 3D printer, if someone can design and model the actual part(s) I could 3d print the parts and then using either carbon or fiberglass laminate the critical joining parts. For example here is a link to 3d printed bicycle where the builder made ABS plastic frame lugs and then glassed the parts with carbon fiber.

Using this same concept create a set of plastic molded with fiberglass reinforced joints (aka lugs) where the struts meet the foils. To me these joints are what are critical. Figuring out the strongest way to join the vertical strut with the horizontal foil. These connecting joints could be printed in different sizes for different boats. sunfishes, lasers etc.

I am a rookie at 3d printing/CAD but will try to come up with something. In my mind in the spirit of sailing, this should be an "open source" design project were people add and contribute freely and openly. I think we all would love to see a you tube video of a bunch of Sunfishes foiling. I know i would!

Maybe we/i should start a new thread.
Bill C
Hi Bill. are you a sunfish owner/experimenter?
If so, I can work on this project a little in my spare time, our of pure design curiosity. (As stated previously, I do not own a sunfish, but if I had one, i would want to make it jump out of the water!) I have solid modelling skills and ideas, but no shop and no 'fish. I want to bring foiling inexpensively to the sailing masses just to see what it does to the sailing industry. Maybe we could carve a little off the powerboat market share while we're at it, and make the water a cleaner place to play (in the summer.. I'm from Canada.. the water gets a little crusty here in the winter for sailing.)
I suspect that making a new thread would alienate other subscribed parties who are interested in this development. people drift in and out of this conversation. It will draw more eyes if the conversation accumulates here in one spot. Just my CAD$0.02

your turn :)
I'd be interested in fabricating and testing foils for a laser.

I have carbon fabrication experience. For a one-off prototype I'd probably use templates and hand shape the structure.

Geoff S.
I just found this forum and I have 2 Sunfishes. I would love to see what can be done to improve the proformance of a Sunfish. Love the idea of foiling a Sunfish. Any progress?


Well-Known Member
The Moth class is a developmental class, and has two very simple foils.

Maybe start there? They sure make foiling look easy!



Upside down?
Staff member
I just found this forum and I have 2 Sunfishes. I would love to see what can be done to improve the proformance of a Sunfish. Love the idea of foiling a Sunfish. Any progress?
Earlier posts in this thread indicate that the Sunfish rig isn't suitable for foiling.

For foiling at 'reasonable' cost, you will need to get a UFO!
What if you used the foiling systems as described above with a more powerful sail rig? I come from the world of windsurfing, going back to 1975 when the sails were basically dinghy sails (a rag on a mast) to more recently with full battens, exotic materials (carbon masts, high tech sail cloths) allowing for super powerful airfoil shapes. How difficult would it be to create a more powerful "windsurfer style" shaped sail to a Sunfish?


Active Member
May I purpose Gentleman that the experiment be carried out in two steps. First sailed
with the original Lanteen rig and then as a Cat rig. I believe the Lanteen rig will be the
most challenging with a narrow pointing ability in respect to wind direction. Ideally a
Super Sunfish rig would be used for the second part of the experiment.