Jet outboard conversion

Scott Farris

Scott Farris

Well-known member
I want to float this by yous guys for your thoughts, cautions and other suggestions or words of wisdom

With only a few weeks left of our season my thoughts have turned to what would make next season a bit nicer. A jet outboard with electric start jumped to mind. I rarely hunt in weedy areas but rocks abound and props get beat. I watch a pair of brothers (friends of mine) get into places with their jet outboard equipped Jon that I would love to get to, but can’t. I read up on the “Outboard Jet” http://www.outboardjets.com/index.phpsite. I’m thinking of using the jet on my 14’ V-hull Starcraft, the 8 degree dead rise sounds perfect and speed is not critical. The boat’s max HP rating is 30-hp and looking at the major out board manufacturers web pages I’m not finding much. Anyone have some good alternatives?

Outboard Jet has a conversion for the Tohatsu 25. I’m presently running the Nissan 25-2-stroke that gets her going about 25mph. Absorbing the expected 20% loss in speed I should still get there :^) Does anyone have any experience with these conversions? The 10 year old Nissan 25 is a pull start, and as I get older my desire to yank the cord in single digit temperatures is disappearing. If I decide to put the jet foot on, I think adding an electric starter kit would make a lot of sense.


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Scott

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Only thing I'd add (and you know this) is that the jets can be tough to drive, in that they don't have a skeg and you need power on to turn. Reverse is worse. I've only driven them a couple times and it was less fun than I woudl like.

The way you hunt that boat, it probably wouldn't matter since you usually put the decoys out from shore.
 
Tod,

That's a brand new prop bought with the brand new boat in that picture. That picture was taken near the end of the deck project. I can't remember if I ever floated the boat before adding the deck, I don't think so but wouldn't swear to it.

River is down another foot, trying to decide if I'll hit the river or climb up a tree tomorrow W/ the charcoal burner.

Sat. was a ball. Got to love it when there are so many brant packed so closely that you can't shoot for fear of killing too many.

Scott

ps: How'd the pictures come out?
 
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Oh, I thought you took that picture today :).

Looked at the temps - 8 tonight.
 
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I didn't see your PS. I got a couple great ones of you with birds working, but they disclose too much scenery to put on the internet. I'll send them to you when I get a chance.

I headed out to check the launches.
 
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I have helped a couple of friends do the switch over. They had long shaft motors and had to build a riser for the transom to get the foot of the jet up to the bottom of the boat. Changing the lower units was simple.

As Todd says jet powered boats are differnt to run. And with that low of a HP motor it will not be very easy at low RPM.

Have you considered a hydraulic trim and tilt system? That could get you prop up higher in the lower water areas and still be brought down for deeper water. The units sold in Cabela's are pretty good, but without a console you would need to figure out how to mount the switches.

Your motor should already have the correct type of flywheel on it so that you just need the solinoid kit and the starter kit. My 7 year old Nissan came with the magneto built in to the flywheel so I would think that your Tohatsu would as well.
 
Scott,

I have installed and run literally hundreds of outboard jets over the years, and I have always strongly reccomended not running a jet on anything less than 40hp. The problem (as you probably already know) you loose about 30% of your power with an outboard jet, sometimes even more! With my experience a 25hp 2 stroke pump on a 14' Jon boat weighing 300 lbs, the boat will plane (sort of) with one person, fuel tank and a dog. Add anymore weight and the boat simply will not plane. I'm willing to bet your boat weighs at least that much judging by the picture.

The second thing is that if you start with a long shaft motor and add a jet, you will need a 25"-27" transom, so you would certainly have to add a significant amount of height to your transom.

The long and the short of it is if you arent running shallow rocky river beds, or consistently 6" of skinny water over mud flats where you are required to have a jet, you would be very disappointed with a jet in general.

Sean
 
Per an outboard/shallow running guru: 8" setback and hydraulic jack plate

Dialing that in, some guys run with only an inch or two of prop below the hull...but that's with 4-strokes and/or low water pickups, etc.
 
Scott, have you thought about putting a prop guard on your outboard. The rockhopper guard has saved mine more than i can count.

Bill, does a low water pick-up and jack-plate set-up give you any advantage when not on plane? Also, how much power is lost when running that set-up on a small outboard (20hp)?
 
I knew I could count on you guys to give me some thought provoking feedback. Sounds like the conversion on my 25-hp isn't practical. I didn't realize a few items like the overall length increase. Lack of power is also an issue, I do want to get up on plane. The chart has 30 to 35 hp at the head as the minimum HP with a 1000# boat. The 25 hp at prop has to equal 30 - 35 hp at the head but Sean, I certainly believe your experience.

The primary area I hunt is all ledge, and depending on river height most of the trip is in shallow drive and very low speed. Very low water and there is some walking involved. That's to get to the easy spots, the locations that can be reached with the 16-ft Jon and jet make me very jealous. A prop guard will certainly extend the life of my props but not add to the locations I can reach. I haven't looked at the hydraulic jacks in person, the catalog makes them sound way over sized for a little 105# 25 hp outboard. Does anyone make a practical low water intake for these little OBs?

Thanks guys, still open for additional alternatives,

Scott

PS: Tod, can't you simply blur or paste something over the statue of liberty so no one will know where we where?
 
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Scott,

I ran a jet on my jon boat for several years. My motor came set up as a jet. 25hp Johnson power head, rated 18hp at the pump. Boat was a 1442 alumacraft. Similar conditions as you stated, shallow rocky river bed with very little weed growth. I loved it for fishing. It would handle two guys and fishing gear. Hunting was a different story. Avery quickset blind, decoys, gun, dog and one hunter was a full load. I could haul another hunter but needed shallow water to get up on plane.

Power wise, I got the performance of a 15hp prop outboard with the fuel consumption of a 30. Like I said I loved it for fishing especially since I usually went alone. I had to raise the transom to around 22inches for this motor which was a short shaft housing.

Prior to the jet rig I was running a 25hp prop motor on a 15ft tunnel hull jon boat. The tunnel hull set up could go almost as shallow as the jet and I never had any prop damage to speak of.
 
Well, I'm not sure a low water pickup does much but enable you to lifet the motor higher when under power....I've never heard of any drawbacks, but I am not an expert on such things. I have been in some rigs setup that way and know some guys on some forums around are very knowledgable about it. A hydraulic jack allows trim adjustment on the fly. Generally, you could splurge on one of the larger models in a light' version so that you only add 30-40#. If it were me, I'd lean towards what I do know: a mudmotor. Preferably a lightweight shorttail in the 23-27hp range...maybe even up to 35hp. I'd throw on a rock guard and proceed to make gravel or metal shavings.LOL That requires $ and a new motor-type. Another option might be to soup up that 25hp to 35 or even 50hp, depending on the model, and then run a jet? Just pontificating, but 25 outboards can be hopped up somewhat and you get the advantage of keeping the same weight as a 25, while having more horses to spare. On smaller boats, you may be able to run a fixed jackplate, with a prescribed setback and reach good water to idle and get on pad in, while still lifting the motor enough on pad to gain rpms and some good hull clearance.....the setback acts like a tunnel, keeping the motor back in the area where the stern wave rises with clean water to feed the prop.
 
Scott,

Definitely do the electric start. My new boat has it. Don't know how I did without it.

Jim
 
Scott,

Keep that boat just the way it is...maybe put a prop guard on a manual jackplate. Get yourself another boat with a jet-drive outboard. Aluminum works great with jets because the ability to drive in shallow rocky areas has inherent issues with rocks and stump hits. I can't think of one steelhead guide in Michigan that hasn't made a run to the welder after a gig at least once to patch a tear or gash. It happens because normally in shallow water situations you are going to be near or at full throttle on step. You do that in a that nice boat of yours and you know that it's gonna be ugly! It helps to have a high output bilge and you definately need a hand bilge in case you fry one. Been there...done that with a gash in the bottom. At minimum a bag of rags and wedges if you can get to the hull from the inside.

I regularly run a welded 1860 semi-vee with a Merc factory 65 jet which is a 2 stroke 90 head in less than 8 inches of water on the St Joe River in Indiana and the Muskegon in Michigan. I'd say 4 inches but nobody believes me. If you come off plane the boat will literally sit down and beach itself so don't be shy....it's ramrod time! As far as driving them goes, that is by far and away my favorite boat to drive. It's more like a snowmobile than a keeled boat.

As metioned above....undergunning a boat with a weak jet-drive doesn't work too well. In my opinion you need oodles of power and the ability to blast out of sketchy situations. Once in a while you will clog the intake grate with cobble and weeds etc. I always have long screw drivers, little pry bars as well as hammers available to work the rocks out and occasionally peen the grate back into place.

Lots of 2 stroke 50's have the same head and therefore weight as a 40. I lean towards a jon-boat with a 50 head and a pump coversion which should bring the output in somewhere around the low 40's or high 30's at the pump which should be okay for pushing a loaded jon. If you're talking ledges and not boulders I'd go with a traditional flat bottom. If noise bugs you then go with a 4 stroke because the jets are usually loud and proud.

I'm not an expert but I've "beaten dog piss out of a few" as we say in Indiana.

Jay
 
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If you come off plane the boat will literally sit down and beach itself so don't be shy....it's ramrod time!
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Hehehehe,,,,,,,, been there done that. Just like going thru a snow drift. If you decide to go for it,,,,,,,,,,,, DON'T STOP!!
 
I had a 90 horse power head jet drive that equaled 65 horses. Underpowered loud screaming sun of a gun. It was always getting stopped up with leaves sand weeds you name it. It would over heat in the sandy bottoms. Never broke a lower unit off the jet drive is about all I can say good about my rig. Could of been a Monday or Friday motor??

Just like anything you get used to driving it. Just a little different kind a like a air boat,but not as loud.

James Roberts
 
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