Dyanfoil's were probably the most high tech water toy ever built. Our tax dollars developed them for the military. ( I did not look at the web site yet) They were released for civilian use in the late 70's and are awsome. You can ride them 45 mph to Catalina in the worst conditions. The way the upper foil on the front reads the water surface and controls the lower foil to keep them stable. They can haul ass, stop and turn on a dime. I used to ride for Kawasaki in the development of the jet ski, and was fortunate enough to get a chance to ride the dynafoil's for about two years. The prop looks scary, but you would never get close to it. The lower unit is engaged with a dead man foot pedal in the right foot well. You have to have weight on it for the prop to spin. If you fell off the dynafoil the prop stops immediately, kind of like the blade on a miter saw.
They would never tell us what the intended use was, but we assumed it was for Navy seals or something like that. I think the technology may be in use on some of the navy large hydrofoil boats.
I found two abandoned ones about 5 years ago in the storage yard at Aha Quin, but couldn't locate the owner. If you could buy a new one I would get one.