No-Boat Water Skis

Background

The Aquaskipper has proven that human power can propel a person above the water using hydro foils. People have attempted self-propelled water skis in the past, but the designs were all horrible. The Mythbusters' Adam Savage tried a typical approach of floating pontoons with flaps for propulsion. They turned out to be unstable and not mobile. What we need a good, functional design.

The Idea

I need to sit down and determine the physics required to keep a person on top of the water using a combination of buoyancy and propulsion. Then I need to explore the design space around these two factors and design water skis that operate similar to the principals used in the Aquaskipper. In my mind I envision something like cross-country skis for water. Cross-water skis?

Progress

11/27/2014:

A Purely Buoyant Solution - Archimedes' Principle

Put simply, the buoyant force on a submerged object is equal to the weight of displaced water. For a purely buoyant design this means displacing enough water to hold up a person. Assuming a weight of 80 kg (roughly the average American male) at standard temperature and pressure, this means displacing approximately 80 liters of water. Sounds like a large volume, but that equates to two skis that are 25 cm wide, 10 cm deep and 160 cm long. So I guess Adam Savage had it about right with his big dorky skis (for the record I was rooting FOR him).

In my opinion this is the worst way to design these skis. This is the maximum footprint of a workable design, so we should be able to stay well below that size by requiring the person to move to stay afloat. More like the Auqaskipper which uses little buoyant force.

A Purely Dynamic Solution - Barefoot Skiing

A rule of thumb for barefoot skiing speeds says take your weight in pounds, divide by two and add 20 miles per hour. This gives around 37.5 mph or 60 kph. That's really fast. The Aquaskipper obviously goes much slower than that. I found a paper on water skiing biomechanics that showed a chart of rope load that was half the skier's weight while going 15 kph.