Jet drive outboards

Got a few pm’s regarding this on another thread about jack plates which i appreciate. I wanna know from those who have them if they love them/hate them and why. There arent many for sale used around here and i know of one somewhat locally that seems like a decent deal.

One thing you have to keep in mind is that you loose about 25 to 30% of the power with a jet drive as opposed to having a prop. More at lower speeds as they are not as efficient of transferring engine power into thrust as a prop is. They hate weeds that a prop driven boat will chop up to a certain degree but will clog up the impeller of a jet drive. On the upside, you can go real shallow . per mile you will use more fuel due to the lower efficiency.

There you have it , thats all I know about the basics of jet impeller propulsion.

I was looking to buy one too but haven't found anything used for sale around here.

If you have hard shallow bottom they are great, they will get you where you dont belong. Bad on gas.

Waggler uses them in the Tidal creeks A
- Alaska !

One other thing If you do get stuck and run out of water with a jet powered oat. Call a tow truck and not Sea Tow as a tow boat won't be able to get to you.

The couple rivers i would use this on get down to a foot or foot and a half deep this time every year, and its mainly sand/gravel where it does. I can get through with the prop, but i usually end up takin some paint off and having to try 3-4 different angles to get through. Im sick of having to nearly idle upstream at 2-3 mph, slightly more throtte and it drops the motor down against the current and i hit more stuff. It runs fairly shallow if i get up on plane but id rather not tear off my lower unit. Will the impeller suck up sand from a foot off the bottom or does this only happen in a couple inches of water? Ive read these things steer like crap unless ur runnin hard? Is it tough to slowly position your boat to fish a hole?

I spent way more time in a inboard jet than a out board. They will suck up sand and small gravel, even to the point of doing them in. They do not turn a boat at low RPMs near as well as a prop. They basically don't function at low RPM's.

That about says it.

Just a couple of other things; carry a screw driver to pry gravel out of the grate, and a couple of small box end wrenches (7/16 I think) to remove the shoe if you get a big piece of gravel in the pump that you can't get out of the shoe.

Someone above mentioned getting stuck after running out of water. What happens is, while you are planing along in shallow water the boat is riding high on a cushion of water. When the water get too shallow and stops you the boat will want to settle back to it's water line, however there is not enough water and you can be a long ways from water that is deep enough to float your boat. The solution to this situation is to carry a come-along, a lot of line, and a Danforth anchor and hope you never have to use the stuff.

Don't forget to lube the lower unit daily, and carry a spare impeller and woodruff key with you.

Have you considered a aggressive skeg guard on your prop driven engine ?
I've run a skeg guard for years , really helps prop protection.

I was launching my boat one day years ago and the fire department was at the ramp with a Zodiac they had just received and were training with. One of the firefighters noticed the weird looking thing on my outboard ( skeg guard ) and asked about it.
Now standard equipment on all FD rescue boats in my city.

May or may not fit your application , but just putting it out there to think about.

I have a hydraulic jack plate on my boat. I use it to switch between jet for rivers and prop for lakes and ocean. It works good, I can fine trim out either prop or jet.
Waggler is correct about lubing daily but I will add lube at the end of the day, it pushes any water out of the bearings and keeps from rusting. I learned the hard way. Seized up jet unit of course not at the landing!

Ive thought about it, but im not sure how thats going to help me get where i wanna go. When its so shallow, if i try planing out, its not that IF im gonna hit, its when, what and how hard. Might save my prop with a guard, but ill still be suckin in sand and crap and be diggin bottom. Ive watched guys with props just throttle down and blow through sandbars, i cant bring myself to treat my stuff that way. Kinda sounds like there isnt a whole lot of good owning one of these. Ive seen a lot of negatives on other sites as well. Maybe i need to skip fishin the river when its low and save up for a surface drive for a few years. Appreciate the feedback.

Surface drives aka mud motors still have a prop and suffer the same road rash in rock. There's no easy answer in shallow water short of a pirogue.
I've studied on this for awhile now and would go with a jet in skinny rocky, mud in, well, mud. If mostly deep with occasional bumps from solid bottoms I'd look at prop with guard or something called a pump jet which I'm not familiar with but want to study up on.
Whether jet or prop there's also tunnel hulls that will raise raise either foot mostly up and out of harm's way. But then you're talking foot specific tunnels, optimizing the hull for best feeding of water to foot, and accounting for the loss of buoyancy due to the tunnel with either pods or weight shifting. And of course you're already aware of the need for a jack plate.

Air boat

JMO, but I would not shy away from jets. As a matter of fact if I ever do the river rat thing again I will build a jet rig with tunnel and pods.
In my reading there's much said of the negatives and there are a few but further research indicates jets run best on hulls specifically set up just for jets. Hanging a jet off a standard hull is going to give you almost all the possible problems one can have with a jet and it's my belief this is where much of the negative press comes from. Comments from those who have spent the time and money to fine tune their rigs indicate the main intrinsic downsides to be loss of top speed vs prop, loss of max payload vs prop, and lower mpg. All of this is a result of the impellers inability to convert engine hp to equal what a prop can.
So if you can live with those three items and are willing to tune your rig I don't see a problem with jets in the right water.

I was going to say this or a paddle is the only surefire way to avoid crunching an outboard foot.

But considering the best of them have baby's butt smooth bottoms, usually with something owl snot slick painted or attached, I'd cringe ever time it got near gravel or rock.

Would love the tunnel, just not in the budget. The particular setup im looking at is a 1548 G3 with a Yamaha 40/30 pump. Both the same year. It didnt appear to have a jack on it, and it looks as if G3 paired these up to sell new, at least according to their website from that time frame. Any idea if manufacturers fine tuned these when set up? Ive read that if youre off high by as little as 1/4 inch, you can cause cavitation or be more susceptible to hitting something if too low. Id be very leary of buying a mismatched boat/motor that someone just found used and threw it on a random flatbottom.

Exactly, I should have specified that.

How much of a pain is it to switch the foot with a lower unit?? Might make getting an 1860 with both the answer to all problems!

Don't lock your motor down and you probably won't tear off your lower unit. I've got 28 years running 40 hp Yamaha Jets. 2 strokes and 4 strokes. I've hit so much stuff over the years, I can't believe I haven't ripped the whole Jet off. Destroyed a foot once.

No the impeller will not suck up sand off the bottom in a foot of water. If you are moving good you can power thru 10/ 20 foot of sand pumping mud. Sand don't hurt things much other than your water pump impeller and plugging up the water jacket pee hole. Sometimes it will get rocks stuck in your thermostat and you have to clean it.

To steer you have to power thru a turn. There is no tiller effect. Slow down in a tight turn and increase power thru the turn. If you power down in a turn, you will not turn and likely crash. I'm a good crasher. Hunker down for them. Crap happens. Just don't sink the boat.

I have no idea what your last question means.

I owned a Valco flat bottom boat and it had a 115 jet on it, no tunnel and went all over the place and never had a problem. That was before any forums or tunnels,
I now have a Woolridge with a small tunnel just big enough to smooth the water to the jet foot. With the jack plate I can fine tune the jet for the load and change out for a prop for lakes and ocean.

I don't know that specific rig. I would assume they paired it to run well but probably not fine tuned, maybe the dealer did. That would be the question for me, was the dealer familiar enough with jets to set it up right or at least the original owner.
Next would be condition of the pump and impeller. Pull the grate and eyeball the impeller are the edges chewed up, check the clearance, check the bearings. This is the heart of the foot if has been sharpened and reset fine but has been done till there's no more life left. Next I'd look at the linkage for the clamshell. Not as prone to wear but it is exposed and can sustain damage.
Back to the rig, I wouldn't worry to much about misalignment unless it's obviously off. The leading edge of the grate should tuck just above the bottom of the hull. The main thing is it should not hang down below where it can get caught. Next check the hull. The transom weld should be smooth and perfectly flat to allow water to flow as one flat sheet to the grate.

We had some of the early tunnels back in '93. The tunnels were too wide. The boat squatted too much. Never hit the foot of the jet. Destroyed the back of the boats. Had boat plugs on both sides of the tunnel. They were destroyed first.

FYI That G3 probably has a the high transom and a short shaft jet. Pretty sure you will not be able to convert to a prop. The transom is too high for a short shaft prop. if you can find one.

Hovercraft
Dennis

How long does it take u to switch out the jet to the prop?

Couple of hours.
This is a early 90's tunnel on a Woolridge. Approximate size 16" wide X 12 inch taper.

I have the g3 1548 vbw with a 40/28 Johnson jet runs good as long as you don't overload it . I've run this setup shallower than I should.

I am more than willing to sacrifice fuel efficiency for the ability to run through shallow water. I have a Yamaha 70 jet and a 30/40 Evinrude. As long as you don't back off the throttle you can run through very shallow water. Without a jet you simply can't get through a lot of areas on the Allegheny River. I can't imagine having trouble in a foot of water!

I have a catfishing buddy who is a pretty big dude. Once we get all our crap in the boat for an all nighter, will this thing move along ok?

How big a ole boy are ya?

The thing with jets is not only do you lose about a third of hp at the pump but they dont have the torque of a prop but for running shallow rocky rivers they are hard to beat just go as big as you can far as hp.

Haha im not huge-225. My buddy has gastric bypass and is now around 280. When he was 440 he sat down a little quick one day in my old 16 footer and i did a back flip over the side into the river.

I'm around 250 and my dad is probably 220 it does pretty decent for us I would like to have a 60/40 or bigger, of course that means a bigger boat and that all means $$$$.