on the wings of a Sunfish

I found a woodworking and sailing creator named Mark on Instagram that has been experimenting with building a wing foil for his Sunfish.

photo by Mark Palmquist

The wing is designed to skim over the water like a horizontal water ski. If it dives, the wing will still have a lifting force due to its curved upper trailing edge. The speed record for a sunfish is around 11 knots in 20 knots of wind. Beyond that bow gets too bouncy and your live ballast can no long keep the hull flat. The wing creates lift on the leeward side forward of the center of effort lifting the hull. Hopefully the wing won’t come loose. It’s basically clamped on.

photo by Mark Palmquist

Mark has two videos posted with the wing foil attached to his Sunfish – the first was very light winds, so not really a good test, but the video below was higher wind. (click thru to watch the video on Instagram…)

Results: a hydroplaning wing works much better on a skinnier, faster hull. The current wing shape is not ideal. Fluid separated on the upper surface. It needs to be optimized for underwater lift, which means having the foil lower and changing the profile shape. Hydroplaning only works well at speeds above 11 knots and that’s the speed limit of the sunfish. Therefore a sunfish would benefit more from a hydrofoil since they work at 8 knots.

sounds like mixed results, so I’ll be curious to see if Mark goes back to the drawing board to tweak the foil shape… or if he maybe has moved on to tweaking his ideas on a sailboat that is a little sleeker than an ol’ Sunfish.


4 Responses to “on the wings of a Sunfish”

  1. 1 Clyde Osterhout March 18, 2021 at 9:23 am

    Interesting! I have a sailing canoe with a high performance rig. It would be interesting to see if a hydroplane set up could be combined with outriggers.


  2. 2 my2fish March 18, 2021 at 10:29 am

    Clyde, from the various comments about this setup over on the Sunfish Forum, I’m not sure it’s worth bothering with….


  3. 3 Max March 22, 2021 at 11:29 am

    I get the impression that the wing might be better used to mount foils from , but of course need rudder foils also, and then it’s not really a Sunfish so wouldn’t it be better to just get a purpose made foiling dinghy?

    Liked by 1 person

  4. 4 my2fish March 22, 2021 at 11:36 am

    Max, yeah I’m not sure what he was going for with the wing. Seems like it would mostly create drag.


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