14ft jet boat build

[catmansteve]

I had another thread discussing whether my boat would be suitable for a jet, finally ran across a good deal on one and thought I'd give it a try. First off, the boat is a 1980 Fisher Marine 1438 mod-V, beam is about 60", rated for 20hp

The motor is an 87 Johnson 40/28 remote steer/electric start
I needed to build the transom up to 27", and since I'm not sure how well the boat and motor will do together, I decided to build a temporary riser/bracing rather than weld a new transom up. If it feels like a winning combo, I want to build a tall transom like you see on Blazers, Legends, etc., but we shall see... Anyway, I would rather go the brick outhouse route than have something fail, so I found a piece of 5/16"x5"x2" aluminum channel and split it down the middle so I had two pieces of 2 1/2" x 2" angle for my risers. I attached two pieces of 3/4" Advantech subfloor plywood for a motor mount, then used 1/2" EMT conduit for diagonal bracing. The pics were taken before I was finished, I added two more braces going from the riser to the top corners of the transom. I used $50 worth of 5/16" SS bolts to put it all together, plus 1/2" SS bolts to hang the motor





I have alot of work ahead of me building a console and setting up the controls and such, and I'm sure I'll have lots of questions, as I've never owned a boat with either a jet or remote steering...

The guy I bought it from, a Tinboats member, said the motor hasn't been run for a couple months, but everything was in good running order. What all steps should I take before running it the first time? I know the pump needs greased every use, would it be a good idea to pull the pump off and check the water pump, check clearance on impeller/liner, check torque on pump mounting bolts, etc.? Or do you think I would basically be spending alot of time and effort for nothing?

Also, the guy gave me an extra intake foot with the motor, but it's pretty beat up. I thought about running it with the old foot for awhile until I get used to it, just incase a rock jumps out when I'm still learning to run it 8) Thoughts?


Also, how sharp does my impeller need to be? It's in good shape as far as not having gouges or chunks out, but not exactly sharp...

I'm planning on gutting the whole boat and redoing all the decks and carpet with non skid painted aluminum vs. the plywood and carpet, and extending the front deck all the way back to the console, sort of a miniature side by side bass boat style to maximize storage space. I'll post my design idea when I get a chance to draw it up...

Well, thanks for reading and stay tuned, more to come. I'm open to all comments, suggestions, looks of disgust, etc. :mrgreen:

 

[catmansteve]

Here's my plan for the layout, comments welcome

 

[jasm2]

Id rig a console into that boat some how and see how it runs before you go all out if it were me.

 

[catmansteve]

Id rig a console into that boat some how and see how it runs before you go all out if it were me.

That's what I plan to do first before I go building a transom or decking it out. I'll probably run it til the end of the summer to make sure it runs the way I want and it doesn't scare the $@%& out of me lol

I figured on making a side console out of 2x2s and 1/4" plywood I have laying around, that will also give me a chance to experiment with console design before I go spending time and money fabbing a console out of aluminum

 

[semojetman]

Awesome build.
Can't wait to see it thru the build.

 

[hotshotinn]

should be a real ripper =D>

 

[catmansteve]

Thanks for the encouragement guys, I hope to test run the motor this week. I'm waiting on my steering helm to get here so I can build the console and get the steering all hooked up, in the meantime I think I'll leave the boat strapped to the trailer and back it into the neighbor's pond to make sure the motor runs ok and I don't have to fix anything with it.

As far as performance, I really have no clue what it's going to do. The 18hp prop put it on plane in 4-5 boat lengths and topped out at 24 mph with one person and a light load, so I'm expecting a top end speed between there and the low-30's

 

[catmansteve]

Backed her into the pond today. Pushed the key in to prime, first turn of the key she cranked and puttered, flipped the high idle lever and turned the key again and she purred like a kitten. Strong stream from the peehole, revs up in forward and reverse, I think I'm in business

While I'm waiting for my steering helm to get here, I decided to build bunks for the trailer, I don't like the idea of a roller trailer and a boat without a solid center keel...

Took a few more pictures on the trailer and in the water. She sits a little low in the rear, but not as bad as I expected with that 200lb motor, this was also with the gas and battery all in the back

 

[bulldog]

Nice. She does not sit too low. I've seen way worse. That thing is going to scoot if you have everything set up correct. Good luck.

 

[bretr]

https://www.outboardjets.com/catalog/ownersmanual/Owners%20Manual.pdf have you read this?

 

[catmansteve]

Yeah, I've read through it about 20 times haha

Bulldog, I keep forgetting to call you, this is the motor I want the decals made for. I wouldn't want anyone to think it was a Mercury :mrgreen:

 

[catmansteve]

Temporary console is finished, all steering and controls hooked up, everything is functioning. Drove it around the pond a bit, everything works as it should, so I think tomorrow will be it's maiden voyage on the river with the new setup! No fishing planned, just a test and tune as I'm sure I'll have to play with the motor height/angle

 

[catmansteve]

I've been having trouble with the motor, but I got it all straightened out and finally got to take the boat to the river yesterday. Determined I have to move everything possible forward, I'm going to tweak the layout a bit to move the console as far forward as the cables allow. Riding solo, it struggles to plane, but add a second person and it won't plane at all with both riding in the back. When I had my brother sit on the front deck, it got up ok, but I'm far from satisfied, and this was with the motor trimmed as far in as possible.

As far as speed, I used a gps speedo app on my phone and got up to 29 mph with two people. I'm going to wait until I get the weight balance straightened out before I adjust the motor height, the pump never cavitated at all so I'm sure it can go higher. Overall I'm satisfied with the starting point, I think 32-35 is realistic when everything is adjusted right

 

[catmansteve]

I moved the gas tank and deep cycle battery to the front, as well as moving the console and seats as far forward as possible. After another day at the river, I think I'm getting closer. It planes much faster now, and floats closer to level, maybe 3" lower in the back. Top speed was about the same, I'm going to try raising my motor an inch and see what happens. Went ahead and painted the console and transom riser, maybe it's lipstick on a pig but at least it looks a little more finished 8)

 

[reedjj]

Now you have room for a cooler or storage behind the seats. Pretty cool little rig. I bet it feels like alot faster than 29mph!

 

[catmansteve]

Now you have room for a cooler or storage behind the seats. Pretty cool little rig. I bet it feels like alot faster than 29mph!

Thanks, and you're right on the money with both points, I've been using the space for a drink cooler, big tackle box, and spare gas can. The layout serves the purpose for now, but come fall I plan on gutting it all, replacing the water logged foam, and starting from scratch with all aluminum decks and framing. And NO CARPET!

It's definitely a lot of fun to ride in, and it handles like it's on rails, I guess because of the mod v hull. My friend has a 500+ hp supercharged inboard jet boat that does over 80, and to me this thing is just as much fun to run around in!

 

[catmansteve]

Just a quick update, took 2 passengers in the boat with me Sunday and quickly found out the boat can't handle it. It was fine with two people, but add the third and it about doubles the time to plane, cut the top speed down to 25. Ran 31 with just me in it, here's a quick video
https://www.youtube.com/watch?v=qYICsx1ZOI0&feature=youtube_gdata_player