I own a Mokai. It's basically a motorized kayak. It uses an inboard 7 HP Subaru Robins 4 cycle engine to turn a turbine pump (jet). I stand up in it to fish all the time, but it is best at just getting you to a spot to wade. It will go upstream on the Cumberland at 3000 cfs with no problems. The website is Mokai.com.

Here is review I wrote about it for another site:
Now that I have about 20 hours on my Mokai I would like to give a brief review.

First the bad:

I received the boat about four weeks after my initial 4 week deliver date. Thatís a 100% error in their ability to estimate a delivery date. Unbelievable!

Iím a lightweight and can only get the boat up to 14.5 mph. I was expecting 18-19 mph. For me this is not an issue, but again they over promised and under delivered.

The noise issue is still there. I never heard the Honda, so I donít know how bad it is, but I need ear plugs if Iím going to run the Subaru over 5 mph. Why they didnít even bother to point the exhaust to the rear, I donít know. Instead the exhaust points straight up and ends flush with the engine cover.

The boat is direct drive, so it starts moving as soon as the engine starts. Mine idles at about 3-4 mph. Many times I want to go much slower. I think it needs a centrifugal clutch. This would eliminate a lot of stops and starts of the engine and give much better control of the speed.

To stop the engine you have to pull a plastic clip from under the kill switch. To restart the clip must first be manually replaced. The clip can be attached to the operator so if he fall overboard the engine stops. What is needed is the addition of a thumb actuated kill switch located at the end of the steering/accelerator bar. This would eliminate a lot of fiddling with the plastic clip.

The cockpit is a little small if you want to carry tackle box, lunch, extra clothes, etc. Not much room to move around with extra gear.

High speed maneuverability is very poor. Itís impossible to make sharp turns at full or even moderate throttle. If you are expecting jet ski performance....donít.

The boat is a little heavier than I expected. One hundred pounds is heavier than it use to be. No way I could ever put it on a car top carrier. I haul it in the back of my Ford Ranger pickup. Lifting one end at a time to only waist high is no problem.

Now the good:

That Subaru engine ALWAYS starts on the second pull when cold and on the first pull when hot. It doesnít take much pull force either. I am really impressed with that motor.

The motor and gas tank can be removed or installed in 2-3 minutes. Itís well engineered.

The engine is VERY economical on gas. I have been out for 5-6 hours and have never even use 1/2 of a tank. Iím sure this will vary with speed, but still, Iím impressed.

The boat is very stable. I frequently stand up while fly fishing with no undue concern. Trying to move around or turn around while standing is another matter.

With only a few exceptions the boat is well thought out and built with quality craftsmanship.

The boatís hull is very rugged. Iím sure it can take a beating.

To me the Mokai is the perfect river/stream boat for the guy who travels alone, getting to remote locations. It is OK to fish out of, but is best at exploring or getting you to that remote fishing or hunting location. Of course it works on lakes too, but that is a waste of the jet propulsion unless the lake has a lot of prop busting rocks.

Just my opinion.