# Outboard jet units?



## PSG-1 (Nov 27, 2011)

I've been thinking about this for a while, and the low tide out here yesterday has finally convinced me, I need to put a jet unit on my outboard! My jetboat has spoiled me, and I'd like to be able to run my Triton with the 50 merc in the same areas I can run with my jetboat.

I found a site where they sell aftermarket jet units (they ain't cheap, that's for sure) It will be a while before I'll have enough money to throw down for one of these things, but when I do, I believe I'm going to get one.

So, I'm wanting some feedback from some outboard jet owners. How do they perform in choppy water? Issues with cavitation? How do they handle as far as steering? Is the steering more or less responsive than with a prop, or is it about the same? (some of the areas I run are quite shallow, and require very sharp turns, and my outboard has a bad habit of cavitating in turns, losing momentum, and grounding in shallow water...I can run that 50 HP in fairly shallow water as long as I'm in a straight line, but if I have to take a sharp curve, that's it.)

Also, I leave my boat in the water (salt water) about 300 days out of the year. As long as I keep it trimmed up when not in use, how well do the components of the jet unit hold up as compared to a regular lower unit? 

How far under the edge of the boat does the unit protrude? Again, I have concerns about running over sandbars, etc. Also, how does it work with power trim? About like a prop, or different?

And finally, how difficult is it to convert from the regular lower unit to a jet unit? Do any of the cables have to be changed out or reconfigured?

Thanks in advance.


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## bulldog (Nov 27, 2011)

Alright, here goes.

Price - you are going to pay around $1000 for an outboard jet unit. 

Choppy waters - you will get some cavitation in chop that is 10" and up. If you slow down slightly, it goes away. If you run a semi V that will help with the cavitation. Also run a cavitation plate. That helps also.https://www.google.com/imgres?q=outboard+jet+cavitation+plate&hl=en&gbv=2&biw=1366&bih=599&tbm=isch&tbnid=iAV-4AO1xa4x_M:&imgrefurl=https://www.sschapterpsa.com/ramblings/outboard_jet_maintenance.htm&docid=eIQ_taEe2eE-zM&imgurl=https://www.sschapterpsa.com/ramblings/OB%252520images/Intake%252520Skirt.JPG&w=626&h=438&ei=A5LSTtG9Ds-4tweFpJ26DQ&zoom=1&iact=hc&vpx=865&vpy=224&dur=309&hovh=188&hovw=268&tx=156&ty=95&sig=105570616056199279209&page=2&tbnh=111&tbnw=148&start=23&ndsp=24&ved=1t:429,r:5,s:23

Handling - I have a flat bottom and i can whip donuts all day long. You have to get used to sliding around corners and drifting. It takes practice but once you get it you can scare your buddies. If you push it trying to take sharp corners it can and will get away from you. also taking very sharp corners causes cavitation. You can put these little wings on the side of the intake grate to help with this.https://www.google.com/imgres?q=outboard+jet&hl=en&biw=1366&bih=599&gbv=2&tbm=isch&tbnid=lAmYbOorbTqKdM:&imgrefurl=https://enduranceequipmentllc.com/outboard_jet_boats.html&docid=FCv-vHwheuntXM&imgurl=https://enduranceequipmentllc.com/uploads/OJ_001.jpg&w=1024&h=768&ei=dZHSTt-dOpG6tgf407ypDQ&zoom=1&iact=hc&vpx=424&vpy=289&dur=5512&hovh=194&hovw=259&tx=190&ty=142&sig=105570616056199279209&page=3&tbnh=113&tbnw=151&start=48&ndsp=24&ved=1t:429,r:18,s:48

Leaving it in salt water - Not sure, we have rivers and lakes up here, no slat water.

The jet unit sticks probably 1-2" below the bottom of the boat. You use the trim to get enough water in to the jet without cavitating at the same time keeping it trimmed as high as possible. 

Hope this helps.

You can switch from a prop to a let in about an hour. Depending on how you run your reverse gate, you may have to put a longer shift cable on.


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## Canoeman (Nov 27, 2011)

You talking 1K for a used unit. 

I payed $1700.00 (just the foot) for my 30 hp 2 years ago new and well over that for my 115.For a new one go to https://www.outboardjets.com (only place i know who has the patent, all other places and outboard manufacturers go through objet), Call and ask for Brian O'Leary, ive dealt with him with my last two purchases and he is a straight shooter.

With a 50 hp your looking at 35 hp after conversion.. As im sure you have been around jets enough to know to keep the weight to a min. 

Here is a load chart..

https://www.outboardjets.com/images/image_chartMTR.jpg

The intake fin's help enough in chop for cavitation but you still will get some, keep it trimmed in and ass heavy in big chop helps a lot and keep the sliding to a min.. as Bulldog said it will cav on ya if you slide to much and have it trimmed out.. i can keep mine trimmed in and slide all day with no cav.

The leading edge of the jet has to sit flush with the bottom of the hull.. use trim to go from there.. the heel of the foot may be 1.5" below..

https://www.outboardjets.com/images/outJetDiagram.jpg

As with bulldog.. im 2000 miles from any form of saltwater.. no idea, maybe one of the coastal guys will chime in.

First time i did the conversion it took me 2 hours, i took my time and made sure i did it correctly, from there it is an hour or so depending on ability.. which looks like you have a skillset for that.


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## Lennyg3 (Nov 27, 2011)

PSG-1 said:


> I've been thinking about this for a while, and the low tide out here yesterday has finally convinced me, I need to put a jet unit on my outboard! My jetboat has spoiled me, and I'd like to be able to run my Triton with the 50 merc in the same areas I can run with my jetboat.
> 
> I found a site where they sell aftermarket jet units (they ain't cheap, that's for sure) It will be a while before I'll have enough money to throw down for one of these things, but when I do, I believe I'm going to get one.
> 
> ...



It may infact be cheaper to sell the 50hp that is on your boat currently, and find a 60/40 jet. 

As far as salt goes, i would think that the oxidation plate would take care of most of it, but maybe consider hosing the impeller and foot out after use? You would absolutely have to make sure you lubed up the jet after every use.


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## Lil' Blue Rude (Nov 27, 2011)

Personally wouldn't waste the money converting the merc to a jet. If it's one of the 59cu t 3 cyl. it would be fine but if it's one of the inline 4's there dogs when you put a pump on them. They just don't have the low end torque needed.


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## PSG-1 (Nov 27, 2011)

Lil' Blue Rude said:


> Personally wouldn't waste the money converting the merc to a jet. If it's one of the 59cu t 3 cyl. it would be fine but if it's one of the inline 4's there dogs when you put a pump on them. They just don't have the low end torque needed.




It's a 3 cylinder, 2007 model.


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## Lil' Blue Rude (Nov 28, 2011)

Not real well versed on mercs after 05 but if it's 2 stroke you should be able to bolt on a set of 60hp carbs. Guys swear by lightening the flywheel on them to get the quicker throttle response and beter holes shot. If it's 4 stroke I personally don't know of any mods, just know they won't out run a healthy 2 stroke.


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## PSG-1 (Nov 28, 2011)

It's a 2 stroke engine.


Thanks for the input so far, guys. I'm still a little ways off from doing this modification, but definitely looking forward to being able to run that Triton where I can run my Aluma-Jet, or at least, having a lot less draft than what I'm currently running with that lower unit.


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## Canoeman (Nov 30, 2011)

Just out of curiosity.. why are you jetting this rig? You already have the ib jet.. Cant handle props no more?


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## PSG-1 (Nov 30, 2011)

Canoeman said:


> Just out of curiosity.. why are you jetting this rig? You already have the ib jet.. Cant handle props no more?




The jetboat has spoiled me, allowing me to run in areas as shallow as 4 inches. When I get out here with the outboard, I'm not able to access a lot of areas at low tide like I can with my jetboat. 

And because this 50 HP has power trim, instead of manual tilt like my old 25 HP, I'm not able to gun it right before a shoal, lift the motor, slide over the shoal, and drop the motor like I could with manual tilt. 

I'm constantly grinding props going in and out of my channel at low tide, as I have to idle, I'm not able to just jump up on plane like I can with the jet. I have to have well over 2 feet of water to get on plane with the outboard, where I only need half that much to plane off with the jetboat. So, in a lot of ways, I'm very limited with where I can go and what I can do with the outboard.


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## Darkside (Nov 30, 2011)

I can add a few items of value. 

*1.* Outboard Jets (Specialty MFG) supply ALL the outboard jet units found on Yamaha, Honda and Mercury jet ready outboard. They also supply units for Evinrude, Suzuki, Tohatsu and Nissan. If there is a jet unit on an outboard, it was made there. The cost of these units will range from $1400 to $2800 depending on the size of the pumps. 

*2. *When a boat is equiped with a Prop Drive, the engine will have to be raised 6-7" on the transom to operate correctly. In most instances, the transom will have to be rased.

*3. *Stainless Steel hardware will bond with cast aluminum when subjected to salt water. The best way to prevent this is to coat the bolts and hardware with Bostic Never Seez. This is the 5 bolts that hold the jet unit onto the outboard, the 4 bolts that hold the bearing carrier in place, the 4 bolts that hold the water pump on and the nuts and studs that hold the intake shoe in place. DO THIS and you'll save yourself a tom of machine and tooling work later.


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## PSG-1 (Nov 30, 2011)

Thanks for the info.

As far as raising the transom, definitely not a problem for me to do, and it would be nice to have a little more freeboard above the water line anyhow, as low transoms are easier to be swamped in rough water.


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