In reply to NOHOME:
I get lots of funny looks, questions, and even occasionally offers to buy it.
As far as draft. Sitting, it draws about 6". On a plane, it draws slightly less. If the bottom is soft it will slide across easily. Sand it doesn't particularly like. The pump sucks all the water out from under the boat and it stops rather suddenly.
I'll bet the sand trick was exciting when you discovered it.
In reply to Keith Tanner:
Yeah, it was quite a surprise. I expected it to slide, not stop. My eldest son came very close to going over the bow and into 4" of water.
I decided today was the day to change the impeller.
It started off perfect. All the bolts came out without any problems, no torch was required. The pump was out and apart in under 20 minutes.
Then it was time to remove the aluminum impeller from the stainless steel shaft. That took 4 hours. It immediately galled to the shaft. 
This is all that's left of the original impeller. I had to remove the blades and slit it to get it off. Tomorrow I'll clean and regrease the bearing and put it back together.
Empty drive tunnel.
The bearing are cleaned and re-lubed and the impeller is installed. Shiny.
Then, since there was a fair amount of corrosion showing, I cleaned it off, primed and painted it with a rubberized undercoating.
Now we are waiting on the paint to dry.
Looking good! I'm interested to see what kind of difference the stainless impeller makes.
In reply to java230:
Me too. The rubberized coating takes forever to dry though, so it's still in pieces. I should be able to get it back together tomorrow afternoon.
I went with the lower pitch, because it seemed to engine was lugging a little on top end. We will see if it helps. The reduced thickness of the blades should help some also.
Old impeller.
New impeller.
Wow thats a huge blade thickness reduction. Its much harder to see on boat props.
Goals: https://www.youtube.com/watch?v=LVr2Ptz4SvE
In reply to Enyar:
I watched that the other day. If there was a river like that around here, I'd be building a new boat. There are a couple of videos of Alaska jet boaters on Youtube as well. There are some very cool and beautiful places in this world.
How is the new impeller working out?
In reply to Fr3AkAzOiD:
The new impeller is significantly better than the old one. Unfortunately, when it hit the water the first day of vacation, it lost the stator or coil and shut down. I'm happy to report it is pretty easy to paddle. We were a half mile from the landing with it puked and rather than calling someone my youngest and I paddled it back to the ramp.
It's backed up in front of my shop now waiting on me to figure out exactly what died.
How did you arrest further galling?
I imagine a good wax or antiseize would help, even in salt water.
In reply to tuna55:
Tuna, it got a liberal application of anti-seize.
Ideally, I'll never have to change it again, so it should last a year or two before I need to get it back apart. 
In reply to Toyman01 :
i know am bringing this thread from the death .But first of all i want to admire your work .
and your engine choice was a spot on . these engines can live forever with little care .
i am planning for a similar build , because i basically hate outboards .
but i have a non mechanical questions .
first of all that engine on a pwc can give you a 3 +- hours on a full tank , so is that tank still ok for the boat or you carry extra fuel.
your load got shifted somewhere in the middle how does it effect the boat.
and i read that the boat see some salt water action . so how do consider its seaworthiness?
am planing for a 25ft with a 150hp engine .with a 20hp outboard spare .
In reply to someone :
Tankage is pretty decent. It will run 3-5 hours on a tank depending on how hard you run it. That's 80 to 100 miles of range which has been more than enough for my use. I do have room for a 2.5 gallon gas can under the back deck. If I know I'm going to be running a long way I carry some spare fuel.
The hull balances fairly well. If I do another one, I'll probably shift the engine and pump back a foot or so and let the pump hang out the back a little. That puts the intake farther under the water and makes it less likely to suck air in choppy water.
As far as seaworthiness, it's decent, but not a ocean going vessel by any means. See above where the pump sucks air in choppy water. This hull also doesn't have a lot of freeboard. I would start with something with higher gunnels to build a rough water rig.
I have thoughts about building a larger version using the engine and pump out of a Yamaha FX Cruiser HO and a large aluminum boat. 180 hp would be nice.
to start with your mileage is very good , and thank you for your feedback its highly appreciated .
my plan is a bit different because i want AC for the cabin, more electric power , more reliability , i already sourced a super low mileage kia-mazada dohc fe engine and rebuild it just to make sure its ok (i actually bought the car rather than the engine alone). which i will use with a jet out of gpr1300 .
the engine should in theory live at least a trouble free 1000 hours in a closed loop system .
The AC is very important because it gets over 120 around here and its easy to do (just buy a custom longer low & high side pipes and stick the blower unit in the cabin ) .
newer pwc engines are not as reliable as they used to be , because older designs were simple and under stressed.
a gpr1300 or even a couple of 700 might be a better choice if you ask me and way cheaper.
also i think a fiber hull is better , at least for me . for better satiability in rough waters.
i think you should totally build it , it will be better than anything out there .
at least i don't have to deal with the outboard drama since i cant and not even willing to buy a new one .for something i will use for a 50 or so hours per year .
someone said:my plan is a bit different because i want AC for the cabin, more electric power , more reliability , i already sourced a super low mileage kia-mazada dohc fe engine and rebuild it just to make sure its ok (i actually bought the car rather than the engine alone). which i will use with a jet out of gpr1300 .
the engine should in theory live at least a trouble free 1000 hours in a closed loop system .
You're new, so you get a pass on the board expectations. Let me fill you in:
That sounds AWESOME,. You can't post something like that and then not have a build thread (with pictures) on the board. 
In reply to someone :
I'm intrigued, but I can't help but think of how the salt water is going to react to the motor. Have anything planned to mitigate it?
In reply to Brett_Murphy (Forum Patrón) :
don't worry i will build it and i will post bucket load of pictures , the only problem right now is getting a decent priced hull, i don't want to deal with the hull restorations so am looking for a new or at least newish hull. but since covid and the fact of me living on an island .prices had tripled the past few months and there is a waiting list for everything .just for inspection the process takes 1 to 2 months .so i think i will get the hull in November.
in the mean time iam building an opencpd unit and purchasing stuff of aliexpress (sensors , lights , etc).
In reply to Mr_Asa :
my mechanical experience is limited to cars , motorcycles and pwc . so i will use a dry exhaust and a closed loop cooling with a heat exchanger .
In theory the heat exchanger should cool the coolant, condenser and oil coolers with using sea water driven by the jet or electric pump or both .
As for engine engine marinization or the lack of it . a couple of blowers with good venting should do the trick . a gas alarm is also a good thing to have .
the fact of maintenance is reduced at least by half .and the engine is waaay cheaper (less than 200 usd ) than any outboard .is very appealing.
and i know car engines are not meant to run a high rpm for long time .but the engine is 160 hp stock and with a tiny turbo you will get an easy 200 -250 hp,500 or more is even possible , google fe dohc.
so the rpm range will be limited to 4000 rpm .after all its not a speed boat .
so with at cost of 1000 usd to have a 200- 250 engine with cabin (ac and heating) and 50 amp of power which can be converted to 110/220 , is nothing.
Toyman01 said:Jet Boat doing jet-boaty things.
Wouldn't a jet boaty thing be a high speed rip upstream?
TMan, is the throttle on the starboard gunnel?
In reply to 914Driver :
Rocks and a fiberglass hull means slow speed for me. That area of the river is 10 miles from the landing and in the middle of nowhere. It would be a 5-6 mile hike through a alligator infested swamp to reach the nearest house. It would be less than fun.
The throttle is on the starboard gunnel. It's just a cheap marine throttle lever. The box it's mounted in, I built.
I still love this thread. Its what made me sign up here in the first place :)
Thanks Toyman, I was thinking motorcycle twist grip on the steering stick. Leaves one hand for hanging the hell on!
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