Kayak appendages

[nemo]

A friend of mine asked me to help him improving kayaks' surfing attitude, and I' thinking about lateral foils near the stern zone, since the forward part of the boat is out of water when surfing waves. Reynolds number is low, is it worth giving the appendages a foil shape or a flat shape is enough?

what kind of kyack and what waves kind of waves, hallow barriely waves or somthing flater and slower?

[nemo]

The Kayak is short, about 1.6 metres, flat bottom, big volume. The waves are hollow, not flat.

[Willallison]

If you're talking about a Kayak in the traditional sense, I'm not sure that I'd agree with your ideas on foil location. Most sea-kayaks have 'foils' - more like a very pronounced flare at the bow to prevent it from nosediving. In surf this problem would be even more critical as burying the bow could result in pitch-poling. Placing foils at the stern would increase the lift at the back, making the problem even worse.

[gonzo]

With a rather flat bottom a surfboard type skeg would work.