These guys with apparently small means have been developing a very interesting project based on a small trimaran on foils driven by a kite. The control problems should be huge since the forces and speed involved are big but they seem to have done a great work on taming those forces: The maneuverability seems great, not mentioning the speed that is awesome (35K).
They are working on new foils and looking for an experienced specialized carbon worker. Based in S. Francisco they are working on this project since 1997....that's a long time. They seem persistent and solid to me: http://project.kiteboat.com/team/
Their goal is :
".... to evolve waterborne transportation to use kites as propulsion. To date, kite propulsion has primarily been used for kitesurﬁng and in single-person traction kiting. In small-scale kiting, the force of the kite can be controlled by an individual holding on to the kite directly, but as the kite gets larger, harnessing its power becomes more difficult. The challenge is to develop winches, controls, and launch and recovery systems for larger kites, boat-specific kites for different conditions, and kite-specific boats and foil systems. Our mission is to design a purpose-built vessel that is specifically designed to harness kite power and to advance kite design and kite controls to the point that power-assisted or autonomously controlled kites can be used by a broad audience."