Alumacraft MV1448 Seadoo IB jet, Still jetting

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PSG-1
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Post by PSG-1 »

That's pretty impressive!! This is the first one I have seen where someone actually fabricated their own impeller duct (scoop) I bet that was a PITA!

Most people just hack the glass hull out of the ski and splice it into the boat (which, IMO, is a substandard design) When I built mine, I used a pump from a Yamaha XL1200.
Jet Drive Assembly.jpg
I think the 1200 and the XL700 are the only pumps which use a bolt in aluminum scoop. All the other ones are part of the fiberglass hull, with threaded inserts on the back end, where the impeller vane/wear ring bolt up to it.

Pretty impressive throttle cable actuator, too! For mine, I took an easier route, and used a simple lever with a pivot point, and attached the cable directly to that, using a ball end fitting for the cable so it could pivot within a notch cut out in the lever.
Control Box.jpg
Anyhow, my boat started out as a 1997 DuraCraft 1648SV which someone nearly killed by painting it with copper paint and leaving it in salt water. I repaired the damage, a lot of it being on the center V of the hull, and then gave it a new lease on life by turning it into a jetboat. The first time with a 1998 Tigershark 1000 cc engine.

And this past summer, I put a Yamaha MR-1 engine in it....it's 160+ HP at 10K RPM's, as well as being a 4 stroke. So far, I'm loving the new engine. MUCH more power than the old TS1000.

My original inspiration for the idea came from the fact that I owned a Sea Doo Speedster jetboat (it had twin engines, just like the one you used in your boat, the 717 Rotax) It was a cool little boat, but it couldn't go in really shallow water, and that's what I wanted. And like the Sea Doo Speedster, my boat also incorporates the use of a 'stomp grate' on the pump intake, for clearing weeds or other debris.


Again, nice work, and I'm sure you will really enjoy being on the water with your project boat. I know I have enjoyed mine for the past 6 years. I've had more fun with this boat that any other boat I've owned.[youtube]ALUMA JET STUNT VIDEO[/youtube]
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ALUMA-JET project:
https://www.tinboats.net/forum/viewtopi ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

https://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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Ranchero50
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Post by Ranchero50 »

Good looking boat, I enjoyed the videos.

Can't wait to get back on the water once the water lowers enough and clears up. On a side note I got some side plates bent for the cockpit walls and they even fit once I was done with them.

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PSG-1
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Post by PSG-1 »

Yeah, I'm looking forward to fishing season this year, especially with the new 4 stroke. Quieter, no smoking at idle, no fouling of plugs when idling for long periods, it will be perfect for trolling at the jetties for trout.

Still doing some final mods myself (seems like with a project boat, we ALWAYS find something else to do, or another improvement to make!) I'm getting rid of that single swivel seat at the console, and putting in a fixed track wide enough for 2 seat to go side by side.

I also have a T-top that goes on this boat, right now the top part is 3 ft wide by 4 ft long, I'm going to increase it to a 4 ft by 5 ft, the 4 ft will be as wide as the bottom of the boat, and 5 ft will give enough rear overhang to go all the way back to the cowling. The top has clips where it can be unbolted from the frame, so, it's not a big issue to take it off and fabricate a larger one. I might even get some of those button snaps, and have the upholstery shop make some clear plastic curtain, then I could put a little space heater in there and stay toasty in the winter!

And at some point, I'd like to put in a set of prow lights (also called 'docking lights') to give me some illumination for running at night. But other than that, I'm really happy with the overall design of my boat, I've pretty much customized it for my specific purposes.

It would be cool to get into actually building boats like this....maybe even being like Orange County Choppers (hence, my youtube videos called "American Jetboat") but I doubt engine manufacturers are going to warranty engines that are used for applications not approved by them! And people aren't going to buy a boat without a warranty. So, while my friend and I had fun making our little series inspired by OCC, I doubt we'll be going into business building these anytime soon, much less being on TV doing it. But then again, I have been on TV before, when I took Larry The Cable Guy oyster harvesting (now THAT was funny!) So, I guess anything is possible!

We're not giving up on project boats, though. Next time, we're going to build one, using one of the Sea Doo 4 Tec Intercooled Supercharged 215 HP engines. That ought to be a fast boat. And after that, I guess the next logical step would be a true 'jet' boat, driven by twin turbines. But I digress.

The only factory built johnboat I've ever seen similar to mine or yours is made by Tracker, and it has a 175 HP Mercury jet drive. BUT, if you notice, they have their engine mounted vertically, not horizontally, like ours. As a result, they have a ridiculous looking cowling in the rear center of the boat that sticks up like 3 feet....LOL I prefer the flat deck look that we have with our custom boats.

I guess the old saying is true....if you want something done right, you have to do it yourself!!
ALUMA-JET project:
https://www.tinboats.net/forum/viewtopi ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

https://www.youtube.com/user/HKPSG1Shooter?feature=mhee

Ride_Klein
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Post by Ride_Klein »

Ranchero-

Thanks for your response in PSG's Alumajet thread. Great build here with lots of good information.

You mentioned you need 30" - 2 feet to get up before adding the tabs, but needed 20" before the tabs? Did I read this incorrectly, that with the tabs you need a little more water to get up on step?

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Ranchero50
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Post by Ranchero50 »

It's all relative. The bottom of my river isn't flat, it has boulders every couple feet so I like to have an extra foot under the hull before launching. Pre tabs and pods the boat launch would be be described as vision distorting. The rear would dig in and shoot the hull out of the water at around a 30` angle and cavitate the pump. Shutting down was like running into a gravel bar, the boat just slowed hard and sank in the rear. With the pods and tabs it launches flatter and comes off plane smooth and flat. The bad is I don't decellerate like I did before but I don't settle as much either.

My tabs are adjustable with bolts now and I'm either going to make them automatic via springs or manually adjustable from the console so I can tune them underweigh. The best part of this boat is I can do what I want. The goal is flat launch and stop with tabs flat and then run on the ride plate with the tabs up for speed and performance.

Check out my goofing off video, that was with the tabs adjusted up and the boat dug in a bit more than the earlier videos. Gives a pretty good show of goofing off but if I launch straight and smooth on the throttle it doesn't dig in nearly as much, just goes.

Jamie

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PSG-1
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Post by PSG-1 »

You could probably use a Teleflex push-pull cable if you wanted the trim tabs adjustable. Then a simple lever and pivot mechanism to operate it, possibly even rigged to a foot pedal.

Thought about doing this on my boat, too, as it did want to porpoise a little bit at WOT. I corrected that by removing my ride plate, and giving it a slight downward kick on the last inch or so, by using my metal brake and making a very slight bend. That eliminated the porpoising, but again, I'd like to have it adjustable, so, I may change the design again at some point, and have a push-pull cable like I mentioned.
ALUMA-JET project:
https://www.tinboats.net/forum/viewtopi ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

https://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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Cartman
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Post by Cartman »

As I am fairly new to the site, I have been cruising the mod section getting ideas when I came across your build. While there are many, many great builds, so far the fabrication level on this one is amazing. Awesome work. Will be checking back for any updates.

the hammer
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Post by the hammer »

Great thread!

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Ranchero50
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Post by Ranchero50 »

Thanks for the compliments fellas. The boat is still snug and waiting for warmer weather. I did open up the shed and made sure nothing was living in it. I even sniffed the seats since the smell of marine vinyl brings back memories for me. :)

Jamie

Ride_Klein
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Post by Ride_Klein »

Ranchero50 wrote:Thanks for the compliments fellas. The boat is still snug and waiting for warmer weather. I did open up the shed and made sure nothing was living in it. I even sniffed the seats since the smell of marine vinyl brings back memories for me. :)

Jamie
Soon the warm weather will return. Was 80 here in North Texas yesterday. I'll send some up your way.

RK

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Ranchero50
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Post by Ranchero50 »

Finally dug the boat out since the weather has conspired to make me perspire and the kids been bugging me to get it out.

Spent yesterday afternoon getting it water ready, washing the funk out and putting the exhaust back together. Once done the boat wouldn't run for long. Suspecting bad gas we drained the tank and took it to the river with a fresh full tank figuring it would eventually smooth out.

Didn't work out.

Today I pulled the carbs off and checked them out, put them back on and while it was barely running ran around back and checked the exhaust flow. No exhaust flow, some dumbass hooked the muffler up to the old hull exhaust port that's blocked off...

Runs much better with an open exhaust...
Jamie

PS, we are off to get it wet, us too.

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Ranchero50
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Post by Ranchero50 »

Hey folks, no real updates, boat keeps tooling along nicely. We've gotten pretty good at relaxing with it, horsing around on the trip up river and answering questions about it.

We did suck up a bird, fish or something the other week in the dark. Felt the thump and the pump cavitated pretty bad. Idled back to the dock and what ever it was fell out by the time I got it on the trailer.

I need to post up another video or maybe take the boat to some new water but it's just too nice to be on the water fifteen minutes from the house.

Jamie =D>

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Brine
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Post by Brine »

Good to see you're putting it to good use.

How's the fishing?

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Ranchero50
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Post by Ranchero50 »

Slow right now. The river is up a foot or so and there's tons of green grass trash floating. The bass aren't where they were when the river was lower and there's more prop guys out now. We did manage to catch an 8" channel cat two weeks ago. Smallest one I've ever seen and it took him 25 minutes to eat the liver off a #4 treble and hook himself.

Other than hooking the exhaust up wrong I haven't worked on the boat this year, just gassed and gone. I keep trying to talk the kid into trying the net a duck on the way up river. He's almost been pooped on a couple times when they rise in front of the boat. Fun times. :wink:

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Gramps50
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Post by Gramps50 »

Nice looking build from the video you would never guess that it was home built. From the 2 threads you and PSG-1 both have great fabrication skill when it comes to the conversions.

What's the advantage of using a jet ski motor as opposed to just using a jet outboard?
--- Gramps
1985 1651 Polar Kraft 20 hp Mercury
HB 597 ci HD DI