With no trim adjustment, I am a bit concerned with how it will handle the CG moving around; say if someone is in the bow versus the stern. Watercraft pretty much restrict the CG to a small location so its not an issue.
You have an X axis to turn right and left, can you design in a Y axis for the nozzle to act as trim?
"place diverter"
In reply to NOHOME:
I imagine this could be accomplished by a hull mounted plate in the jet stream.
Trim could be a problem, but I think I can manage most of that with weight. The longer flat bottom hull should also help some. If it rides bow high, I can add a wedge to the bottom at the transom or a set of trim tabs. We'll just have to get it in the water and see.
No power trim on that one? On my Polaris, there is a trim ring that is power actuated, but I have seen plenty of folks remove the motor after it fails and just set the trim ring to where they want it. Perhaps you could add something from a junker ski?
In reply to pinchvalve:
I've been watching Ebay for a nozzle with reverse and trim. So far all I've found is they made a couple of different size nozzles for the 650 Yamaha. I've got a nice one that doesn't fit. 
Small update.
Yesterday I drilled two holes in the transom for drain plugs, one on either side of the pump tunnel. I packed them with epoxy and let them set overnight.
I got home early today and pulled the boat out of the shop to work on it. Finished up the drains and got the transom sanded and ready to fill the holes. Mixed up a batch of filler and, once again it starts raining. 
If I was trying to grow grass or a gargen, it wouldn't rain for months. Naturally since I need dry weather, it's raining every day. I'm pretty sure Mother Nature hates me.
I prevailed though. The transom is filled and will be ready for sanding and paint as soon as the epoxy sets.
Drains.
Transom filled, no more holes.
dammit this is awesome.
Been wanting to do something similar with a old starcraft v-hull and a ski for awhile now. Seems perfect for the oyster bars/mud flats around here.
Wooohooo!!
Finally a day of blue skies and no rain!!
Time to get the rest of the glass work done.
I started out this morning doing my favorite part of fiberglass work. Grinding. Lots and lots of grinding. This time I bought a Tyvek suit, hood, gloves, the works. For once I didn't end up covered in glass.
That done, it was time to figure out how to fill the huge crack where the motor mounts were. Filling them with epoxy and filler would be too expensive so I used a couple of pieces of walnut I had laying around. Run through the table saw to get the angle close, covered with epoxy and pushed into place.
Then I glued down another walnut wedge to taper the mounts back to the level of the hull.
Next it was time for glass cloth and epoxy. This side is getting a layer of 24 oz cloth and two layers of 6 oz. This is the layer that is going to do most of the work of keeping this thing together.
24 oz compared to the 6 oz I used on the bottom.
The finished product looks like this, complete with the damn may flies.
Hopefully by tomorrow I can sand the flies out and apply some paint. Then it will be time to mount the engine and get it running. 
Toyman, You're my hero. LOVE the build.
Are those mayflies or lovebugs?
In reply to moparman76_69:
Yes. May flies, love bugs, whatever you want to call them, they love wet epoxy.
Question not necessarily about your build. What would be bad or good about using two jet skis assuming the same models to make a twin jet jet boat? It looks like in theory they would fit in your boat.
I mean, if one is good, numerous is better right?
In reply to Thinkkker:
There are factory boats with twin jets and I've seen a build for one, but no videos of it running.
It could be done, maybe for the MK2.
Thinkkker wrote: Question not necessarily about your build. What would be bad or good about using two jet skis *assuming the same models* to make a twin jet jet boat? It looks like in theory they would fit in your boat. I mean, if one is good, numerous is better right?
There is such a build on Youtube.
Hey, guess what! It's still raining. I guess yesterday is the only break I get, as far as weather. It was raining cats and dogs when I got home and supposed to rain every day for the rest of the week.
Change of plans, I'll save the painting for another day.
I got my eldest son to help me set the engine in place so I could start planning the rest of the install. This afternoons project was exhaust. I wanted to use the factory muffler and through hull fitting because I'm cheap. Unfortunately the muffler is a really odd shape. Since it's a wet muffler, it has to stay right side up to work properly. Lots of shuffling of parts and hoses and I came up with this. This arrangement lets me use the factory hoses as well, I shouldn't have to buy anything. 
The muffler is about 4" above the bottom of the boat on one end and 6" on the other, so I needed to build a mount for it to sit in.
What I ended up with so far is this. The blue line is the steering cable, the black hose is the suction from the auto-bailer.
There is still a little construction to do, and it needs to be glassed into the hull, but it should get the job done and it keeps the muffler below the top of the seat.
More to come as it happens.
My hero! At least you will be when it runs and floats on its own. 
You should name this boat "Uncle Roman"
It's probably going to be called "Little Squirt".
I love it too! This will be fun.
I'm quite happy to see this build. I'd enjoy building something like this for cruising around the local creeks and rivers.
Now I wish I hadn't gone on YouTube.
Or Craigslist
https://pittsburgh.craigslist.org/boa/4681983968.html
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