Home grown Laser Hydrofoils

There's been the idea of having the controlling foil in the front of the boat with the "wand" controlling the angle of a forward bow foil, allowing the rudder to just be a rudder (Necessarily deeper than normal for a dingy that a foil has been added on to).

I'm going with the (1) layer of kevlar approach to provide a smooth top surface front to back, on my second version of foils, and applying the curved Mylar gap seals to the bottom of the foilfs. Thanks for the suggestion, and pointing me in the right direction on this.

 

I think your new foils should have 10 or 20 percent more span and chord, which I expect would make take offs happen at a significantly lower speed. While you're at it, you might taper the new foils. Maybe the tip chord should be about half tne root chord. This will help a little with induced drag and a lot with structural issues. You won't need as much carbon in the spar. As I recall, the Decavitator human powered hydrofoil had a big wing and a little wing. The big wing made take off easier and allowed the boat to pick up some speed. Then the big wing retracted and the little wing did the whole job. This was easier because only the canard chamged pitch, controlled by skimmers. I'm guessing the system on Moths might be more efficient, though.

I think your foils may have a lot of intersection drag. You might consider wing fillets, as on airplanes. Part of the fillets should extend downstream in a little "stinger".

BTW, I'm impressed that you could make this work.

 

Hi all,

I hope you’re all doing well! I’m currently engaged in a Design Technology project for my IB Diploma, focusing on designing a foil for a Laser sailboat. Having done some research, I’m quite fascinated by the possibilities and challenges associated with such a project.

I've been looking into existing designs and came across discussions here, especially those surrounding the innovative surface piercing foils and the various methods of creating altitude control. However, I would love to gather more insights from those of you who have experience or expertise in this area.

To help guide my project, here are some specific areas where I’d greatly appreciate your advice:

• Design Considerations: What are the critical parameters to consider when designing a foil? For instance, aspects such as foil shape, dimensions, and angle of incidence.
• Material Choices: What materials do you recommend for constructing durable yet effective foils for a Laser?
• Best Practices: Are there specific construction techniques that ensure both performance and durability?
• Challenges: What common challenges did you face during your design or building process, and how did you overcome them?
• Resources: Are there any reference materials, websites, or communities you recommend for ongoing research and support?

Any information or experiences you could share would be invaluable to me as I work on this project. Thank you so much in advance for your time and insights!

Looking forward to your responses!

Best regards,
Grace

 

Take a look at this one:
https://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=8938139&fileOId=8938140

 

Without wanting to be too much of a downer, it can be said that the possibilities are limited significantly by the physics of the Laser and the general lack of interest in foiling boats. Foiling is great, but the hype vastly over-plays the actual number of foiling boats; they just aren't all that popular even after many years of publicity.

The Glide Free Laser kit was created by a industrial designer (IIRC) and an engineer who was a world class dinghy sailor and created the first mono-foiler. Unless you are similar in experience to them, you will be very unlikely to create a superior package. One thing that could work better, perhaps, would be a bow-mounted wand but how do you actuate the flap? One could make smaller foils but at what cost? If you make expensive foils to reduce drag then why not put them on an inherently better foiling platform and rig?

The Laser has basic problems as a foiler, as do almost all boats. Foilers require a rig with very low aerodynamic drag, and yet they need to get moving fast enough to foil when they have to get over the extra low-speed drag of the foil. So foilers inherently need a big, low drag rig, but a big rig is not something that a Laser can carry because it is only a hiking boat and a skinny one at that. Low drag rigs tend to be very high tension and therefore expensive - look at the Moth's vang loads and the gear required to achieve it. That increases the inherent cost of the boat.

The aero drag is such an issue that the Glide Free guys often used the Radial rig because it has lower drag due to its smaller size, but of course that reduces speed in non-foiling conditions and increases the wind required to get on the foils. The only time I used a Glide Free setup it felt surprisingly small when on the foils, but I think even the creators admit that it's only for fun reaching back and forth - the aero drag of the rig is too great to allow it to go upwind, and the high apparent wind means that you run out of righting moment very quickly.

One can say that once you accept the inherent issues of a foiler, and its inherent strengths, then a dinghy doesn't make too much sense in many ways. In conditions in when foiling really works, a board works better at much less cost and a kite is vastly quicker at much less cost. In conditions when a conventional dinghy works well, no foiler works well. That doesn't mean that foiling dinghies are not great - they are - but it may indicate that they will always remain a small niche.

May I ask whether you currently own and sail a foiler? Do you see many foiling Lasers where you sail? If the answer aren't "yes" and "yes" then why assume that the potential is so high?

 

If its purely an academic exercise,don't be limited by the concept that Moths have to use within their rules and which has been adopted by the Waszp as an imitation of what the Moth has.I didn't see that there is a plan to flood the world with foiling Lasers or indeed any other variation but where to start?It needs to generate enough lift to get the weight of the boat and sailor out of the water and the main variables are foil section and area.The challenge is that with lift,there comes drag and the foiling appendages need to be strong enough to deal with the loads.I suggest making some assumptions about the weight of the sailor-say 85Kg and doing some preliminary calculations to see where it leads.

Would you be following the well worn path of a daggerboard with a full span foil?It might be the only practical route for a Laser hull but the pioneers used different approaches,see what Eric Tabarly,James Grogono and the Hydroptere team did for a bit of background.There is information online about the foiling Optimist project and lots of other student projects.Creating a design that would work is a big challenge and if you go on to actually produce the parts another range of skills will be called for.You can certainly do it without 3D modelling skills but it may score higher marks if you can demonstrate those too.

Good luck with the project.