Jump to content

The Sportfoil returns...


MikeStevenson
 Share

Recommended Posts

Hi,

I had some time over the holidays and was motivated to scan the old Sportfoil plans and post them on the free plans page. They're up now, so you can download them if you're curious. The plans were the second set Peter drew up (not second boat design though) so they're not int he style he settled on eventually. They're still interesting though.

http://www.stevproj.com/Planlets.html

I'm going to start work on another free plan in the next week or so. This one is for a sailboat Peter did quite a long time ago (over thirty years), but it's not very big. I had lots of fun playing with it though, and still do! (no more hints...)

Mike

Link to comment
Share on other sites


Mike, how fast did the boat run when it came up on the foils. Do you know how fast you went with the motor that you show in the picture? Do you still have the boat and when was the last time you took it out?

Do you have any more pictures? :roll:

:lol: Ok I ask to many questions. But it looks like a good winter project.

Link to comment
Share on other sites

I'm afraid this is a pretty old project (the second one Peter did plans for!)

I was six or seven when he did the Sportfoil, so I never got to go on it (maybe I did-I have a very vague memory of going out on it.) I think it was about seven or eight knots to get on foil, depending on weight load. Don't use these as definitive figures: We're all going to have to wait until someone (Konrad?) makes one and gets some new numbers.

I do know that the Hydroflier was built with the idea of being able to fly in a five-knot-zone. The Sportfoil couldn't do this, thus the assisted-lift design for the Hydroflier. This gives us a sort of low-end idea of speed for the Sportfoil, and the upper end I would guess around 20 maybe?

Now that I know more about hydrofoil concepts, I can tell that the Sportfoil and Hydroflier could both use a variable-pitch prop system. Unfortunately outboards don't have this feature! You're going to be limited by the pitch of your prop: A hydrofoil on foil (flying) has very much less drag than a boat shoving water out of the way (I don't know how it compares to a planing boat, but at the relatively low speed of 15-20knots, I suspect the hydrofoil will have less drag. At higher speeds the planing boat would begin to get the edge, thus Unlimited Hydros run as planing boats.) The foils down in the water are a big drag at first, and you need a fair amount of power, then as the boat rises, suddenly the drag goes down and the boat accelerates. If you could "shift gears", you could take advantage of the low drag and go pretty fast. As it is, you're going to run out of prop (your speed will be high enough that the prop will be less effective and will run out of thrust at some point: your top speed.)

If someone with a Sportfoil gets bored with just playing with it, a series of tests with different props would be interesting. If you have too high pitch initially, it's going to be hard to get the boat up on foil quickly, but that may not be an issue. Putting a larger motor on to go faster is not really the solution in the case of a hydrofoil, though larger motors will have props designed to go slightly faster. Ten to fifteen horsepower will be fine for the Sportfoil. It's very light and simple. Remember that the Hydroflier was working fine with a Honda 5hp. 4-stroke w/stock prop, but that was with assited-lift; the Sportfoil is pure hydrofoil lift so it will need to go faster to fly, and need more power.

I'll look for more shots, but we don't have much from that period of time. There's a nice Sportfoil builder pic in the Builder Pics Section of our website. The original Sportfoil was scrapped around 1976 or so, as it was damaged in storage and we were busy with other stuff then.

Mike

Link to comment
Share on other sites

To bad she had to be scrapped, but I would like to see some more pics if you have them. I'm not much of a power boater but in my younger days I used to race Hydroplanes. But once I took to sailing I have never turned back. But as a toy the Hydrofoil looks like fun. One of my friends would like to build one. And maybe I will to. You never know. :P

Link to comment
Share on other sites

  • 17 years later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share



×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.