small jet ski engine?

I am a crazy 72 year old gear head and own a Mini with a turbocharged, 3 cylinder, 1.5 liter engine that produces 134 hp and more importantly, 162 ft lbs of torque. Surprisingly it has very little turbo lag so when you put the pedal down, she goes.


David

Steve91T said:

A 6BT in an S10? I have got to see that. I have a 6BT in a 99 F350 and absolutely love it.

I agree, no such thing as too much power.

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I have a rat rod 37 ford PU with a 700hp Caddy V8. This weekend it took 2nd place in a car show......

Nomad Willy said:

OK my bad. That was my oversight.
I’d like to hear from jimisbell and see what kind of boat he has.

I now know he is building a rowboat. That would assumably be FD so only a very small amount of power will be required.

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My dinghy will be about 10 foot because the beam of my boat is only 11'10" and I want to carry it on the davits and NOT snag the pier as I pull away. Not a fun occurrence....dont ask how I know....LOL


The reason for a jet is that its hard to steal without taking the entire boat.


I am thinking the jet unit, but not the engine from a jet ski and use a smaller upright engine with horizontal shaft to drive it.

djmarchand said:

I am a crazy 72 year old gear head and own a Mini with a turbocharged, 3 cylinder, 1.5 liter engine that produces 134 hp and more importantly, 162 ft lbs of torque. Surprisingly it has very little turbo lag so when you put the pedal down, she goes.


David

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I am only 82 and my ride is a Saturn Sky Roadster with a tune that gets 181 mph at top end. Dont want to go that fast in a ragtop. Really scarry..... The Sky has too much turbo lag but I am closing in on the problem. The tune does help some, down to less than 1/2 second. zero to 60 in 4 seconds........

Dont know how much you can get from small displacement but I had a Honda 50cc (rotary valve) bike that I modified to cruise at 60 mph. Dont know how much horsepower that takes. It was hell on spark plugs.. welded them shut in about 10 miles....LOL

I’ve been thinking about building an extremely shallow draft fishing skiff. I had a board boat with a 30 pound thrust trolling motor on it that was a lot of fun. The problem was that with the engine down it drew at least six inches. With an electric jet drive I bet I could get the draft down to about two inches. There are jet drive surf boards so I know the drives exists but I can’t find anyone just selling the drive.

Jet surf boards

https://youtu.be/5Xg7CIxBw-U

Seriously check these things out! They’d be perfect strapped to the back of a trawler! They need like an inch of water!

https://youtu.be/S0Ue-a8FWho

My son.. A charter member of the RNYC. Red Neck Yacht Club.
Just to show what is possible. All designed and fabricated by him..
Other vids of stuff he's built on YouTube search Ranchero50.

I still want a hovercraft. Wanted one since seeing ads in Popular Science as a kid. A Jet ski powered hoverdink would be a novelty.

Solly said:

My son.. A charter member of the RNYC. Red Neck Yacht Club.
Just to show what is possible. All designed and fabricated by him..
Other vids of stuff he's built on YouTube search Ranchero50.

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Well done!!

Kid has some skills!!

I too am a charter member of the redneck yacht club!!

jimisbell said:

Who or what is SBT

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https://www.shopsbt.com/

Williams builds a 9' RIB with a 50 hp Rotax jet engine. Total boat and engine weight 465 lbs. Engine weighs about 125 lbs.

I have a Nautica dinghy that size with a 90hp jet. It was novel to me, so I had to try it. Interesting little boat, but what I learned was that it would have been a somewhat difficult “add on”. The nautica has room integrated in the hull for the intake shoe and a partial tunnel for the jet and steering. It’s an old two stroke so it’s loud and it smokes. At first blush, fitting a jet ski would not be an easy thing to engineer, and I love to cobble things, just to try to make them work.

"I don't think he fits the Chevy 454 in the Nova profile."

I am past mid 70's and have a 79 Caddy Sevile, which is basically a Nova platform.

It has a 455 OLDS for power.

Top tossed , rear doors tossed and frame shortened. When GM built only 50 they were called Milan.

The white roadster with red interior , is what mine looks like.

https://www.google.com/search?q=cadillac+milan&client=firefox-b-1&tbm=isch&source=iu&ictx=1&fir=dTwDe_Ltm0we5M%253A%252CdBBbwPLvFeDJ3M%252C_&usg=AI4_-kT-A4Gg5VaMdF_T093qeWX_3Od0kQ&sa=X&ved=2ahUKEwjO6d6uh_fdAhXNtlMKHdc6AoUQ9QEwAHoECAEQBA#imgrc=dTwDe_Ltm0we5M:

Here's an 8' jet drive RIB that has an amazing 6-person capacity. There's a nice video too. But this might only be sold in Europe.

Hydro-jet inflatable boat / rigid / 6-person max. / teak deck - 250 / 250X - AXA d.o.o. - Videos

mahal said:

Here's an 8' jet drive RIB that has an amazing 6-person capacity. There's a nice video too. But this might only be sold in Europe.

Hydro-jet inflatable boat / rigid / 6-person max. / teak deck - 250 / 250X - AXA d.o.o. - Videos

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Here is their complete line. The company is Aquanami.

aquanamihtml

Now, I see lots of interesting designs. What I don't know is if they've produced and sold any. I know they're looking for distributors but also for production partners, so something tells me they have the ideas and design but that's as far as they've been able to go.

I have a problem with the whole concept of a tender that cannot be steered unless it is under thrust. There are lots of jet boats on our western rivers and lakes and they all are a handful in the marina and at the docks.

Woodland Hills said:

I have a problem with the whole concept of a tender that cannot be steered unless it is under thrust. There are lots of jet boats on our western rivers and lakes and they all are a handful in the marina and at the docks.

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You cant steer ANYTHING that is not "under thrust." Canoes included.

Woodland Hills said:

I have a problem with the whole concept of a tender that cannot be steered unless it is under thrust. There are lots of jet boats on our western rivers and lakes and they all are a handful in the marina and at the docks.

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Wifey B: Clearly poorly designed or operator doesn't know what they're doing. Can do things with a jet that you couldn't possibly do with a prop drive if you know what you're doing.

And, yes, it requires thrust. Without thrust, nothing moves. Unless you're coasting down a hill maybe.

We saw several jet boats operated by a small fishing charter outfit out of Sandspit. They fish-tailed all over the place when leaving the marina at slow speed. Upon conferring with captains of the “other” charter boats, they indicated they were less than suitable for their intended purpose for fishing and high speed travel in the open ocean. Around here, jet boats are typically used in riverine situations.

Jim

JDCAVE said:

We saw several jet boats operated by a small fishing charter outfit out of Sandspit. They fish-tailed all over the place when leaving the marina at slow speed. Upon conferring with captains of the “other” charter boats, they indicated they were less than suitable for their intended purpose for fishing and high speed travel in the open ocean. Around here, jet boats are typically used in riverine situations.

Jim

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Sounds like a problem with drivers, not the boats. They are used in open water here on the South Coast...by drivers that know what they are doing. As to the steering without thrust. I defy anyone on this forum to steer their Trawler or Sailboat without thrust.


BTW, never knew that their "Intended Purpose" was Fishing and high speed travel. They are for fun in the water and dont know anyone that fishes from them or travels on them. That is a "straw man" argument. Doesnt exist!!!

ghost said:

I have a Nautica dinghy that size with a 90hp jet. It was novel to me, so I had to try it. Interesting little boat, but what I learned was that it would have been a somewhat difficult “add on”. The nautica has room integrated in the hull for the intake shoe and a partial tunnel for the jet and steering. It’s an old two stroke so it’s loud and it smokes. At first blush, fitting a jet ski would not be an easy thing to engineer, and I love to cobble things, just to try to make them work.

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I have a 15’ Nautica with a 95hp Mercury waterjet. Essentially an older 95hp 2stroke outboard motor flanged to a pump. Mercury no longer supports it with parts and three authorized factory service centers refused to service it. I had to remove the engine from the boat and send it to a third party shop in Miami for rebuild. It is noisy. It does smoke. It doesn’t steer well at idle. It is heavy. The whole boat comes in at 1400lb which is all that my crane can handle (1500lb capacity). Dealers don’t want it in trade in (I tried).

Upside is, it is fast, it is not a candidate for motor theft (especially in the islands), boarding is easy from the water at the stern. No dangerous prop and it even has a swim platform.

I thought it would be great in shallow water like in the vids. Wrong. It sucks up sand and engine cooling water comes from the jet drive and plugs up the cooling ports with sand. Thus the engine rebuild after an overheat situation. Lesson learned, keep in 12” of water or more. (I ran the bow on to a beach. Stern was in about 6” water. On the way back to my boat the engine overheated and died. Always keep a paddle on board)

jimisbell said:

Who or what is SBT

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Jetski re-maufacturer.
https://www.shopsbt.com/

After all this discussion I am narrowing my investigations to maybe a vertical.one cylinder engine direct coupled to a simple impeller type water pump. Hose to an intake and hose to a rotatable ejection port near the stern. Nothing fancy, just a gasoline driven water pump and two hoses.

Maybe something like this mounded in the center of the boat under the seat.





This pump is a powerful unit, great for flood water removal or gold-panning/processing operations

•KOHLER engine: Brand recognition, high quality, stable and reliable power output, durable product with commercial-like engine consistent stability,

•Longer life: Use silicon carbide as material for mechanical seal, reduced abrasion in working situation and extend pump life

•High Performance Spec.: improved design for impeller and volute, increased suction, delivery and flow of water pump

•Consistency: Through better process control, manufacturing equipment and finished product testing

SPECIFICATIONS:

Recoil Start

Cast iron impeller

6.5 hp /196CC

Low oil shutdown

3.6 Liter Fuel Tank


Cast-iron cylinder liner

Delivery capacity: 167 GPM

2 inch inlet and 2 in outlet

Mechanical Seal is Silicon Carbide

Suction Head 30 ft

Total head Lift 110 Ft

Dry weight is 60lbs

approximately 22 X 14 X 16 inches

Meets EPA

Comes with accessories- strainer, hose band, pipe connection, pipe joint.

Jim I think you should find a centrifical pump. That’s the road to high velocity discharge. You can identify high velocity pumps by their impeller that has a large peripheral dia and a not so wide or thick. A bit like an very old car tire. Large OD and skinny tire.

But that’s based on the assumption that high velocity low volume delivers the best thrust. I mention this because most over the counter pumps you’ll find will be low volume. I may be wrong so verify my theory.

Is the pump above 60lbs w or w/o the engine?
2” outlet sounds like low volume.

McGillicuddy said:

...It doesn’t steer well at idle...

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Exactly!

McGillicuddy said:

I have a 15’ Nautica with a 95hp Mercury waterjet. Essentially an older 95hp 2stroke outboard motor flanged to a pump. Mercury no longer supports it with parts and three authorized factory service centers refused to service it. I had to remove the engine from the boat and send it to a third party shop in Miami for rebuild. It is noisy. It does smoke. It doesn’t steer well at idle. It is heavy. The whole boat comes in at 1400lb which is all that my crane can handle (1500lb capacity). Dealers don’t want it in trade in (I tried).

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Interesting to note changes over time. Our 15' Williams weighs 957 pounds. Also, quieter engines. As to steering at idle, you use thrust. I don't know any boat that steers well at idle but you learn to steer a jet and use thrust properly. Your comment on shallow is very true. People equate shallow with zero or 6". I blame part of that on the builders who say can run in 8" of water and things like that. We set 2' as our minimum. That's still very shallow and plenty good. Wish the builders made it clear as to the risks of running under 1' or so. Sorry you had to find out the hard way.

Lightest jet I know is 9' and 465 lbs. Lightest diesel I know is 10'6" and 770 lbs.

The Williams Dieseljet 445 listed at 15’ length and spec said weight is 1825lb. That’s the smallest diesel they make I think and too much for my crane. Recommended for yachts 73’ and above.

Regarding thrust, I find a regular outboard at idle provides more than sufficient steering thrust when docking at my swim platform unless it’s really windy. Although I do use bursts of jet drive power to steer at low speeds I am not a fan of the technique. Much prefer a stabilized approach. Much like when landing the plane. To each his own I guess, have also been waved down in marinas for being perceived as moving to fast when running revs barely enough way to maintain steerage without having to turn the steering wheel lock to lock to keep it going straight.

Yup, learned the hard way about water depth. After viewing videos of jet boats running in very shallow streams and jumping over small islands I became inured to shallow water danger. Thought I could just run it on to a beach. Expensive lesson.

My boat model also comes as an outboard powered version. With a 40hp Yamaha it was 865lbs. Considered buying one as I like the hull but dealer would not take the jetboat in trade. Said there was no market for them, even with the 12 month warranty on the engine.
I could put it on Craigslist I guess but I don’t have the patience for the nonsense that comes with a CL listing and I don’t have a trailer.