This Jetlev is a great concept and looks like FUN!!
Perhaps Painless and Fireman have built something similar and used it on a lake or river? I did some years ago - it didn't take off but it was a means of getting around on water......
As a crew at work, we took 2 fire engines to the local lake, in fact a disused quarry. We took 6 sections of short ladder and lashed four together in a square, then used the other 2 sections as bracing and a 'floor'. We then 'waterproofed' it and gave it buoyancy by placing the structure on a large plastic salvage sheet, folded up the sides and lashed it onto the ladders using a line. A portable fire pump was placed onto the floor and the suction hose and filter was placed and submerged in the water to the rear (similar to the Jetlev). We finally took 2 angled couplings off the hydrant standpipe, connected these to the water deliveries on either side of the pump and connected a controllable nozzle in each. The pump was started, water sucked up and discharged through the rearward facing nozzles. Opening and closing the nozzles gave us direction, but not much speed. Still, it worked and showed that the reaction from the jet of water was enough to provide forward motion.Great fun at the time and a good application of ingenuity and adaptability. Wish I had some photos.
We did this a couple of times but lost interest when we realised that the lake was 30ft deep and that if it capsized we would loose the lot...in fact, another crew tried it on a shallower lake at Hewell Grange, a local prison, and did sink. Fortunately they were able to retrieve the gear. As an aside, Hewell Grange was used by US Forces during WW2 and it was rumoured that when they finally left, Jeeps and other equipment were dumped in the lake there. This has fascinated me for years and it was only recently that I found out that the kit wasn't dumped in the lake - it was buried in the grounds and forms part of the dam wall for the ornamental lake. Not much chance of recovering that really!!
Cheerzen