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teddillard
10 February 2012, 0328
Anybody ever done one of these?

http://images.craigslist.org/5L35G55F53L13M23Hdc29563418fa8f061dc4.jpg

It has no motor, and it's my favorite four-letter word. FREE. :D

I've never even seen the insides of one of these things... but email has been sent. :O

SplinterOz
10 February 2012, 0340
I have seen a youtube video of one .....
http://www.youtube.com/watch?v=6wK_R7ynkJU

SplinterOz
10 February 2012, 0350
Motor looks familiar too :)

teddillard
10 February 2012, 0408
Just what I was thinkin'. :D

larryrose11
10 February 2012, 0702
My expirence with these this suggestt that ducted water drives sucx compared to traditional exposed props.
I know, it defeats the safety aspect of them. Jet ski's usually have 100 HP engines in them! This is to ovdercome the total suckage of the jet drive.
Now, think about this, a 8 ft boat with a 100 HP outboard engine. it would be scary fast!!
Here is a video of a small race boat with 25 hp outboard:

http://www.youtube.com/watch?v=iETKA0R1Xr4&feature=related

Converting one to el drive will work, just dont expect on par performance. If you willing to ponny up and spend a lot of money on a AC-50, and Lipo bats to back it up, that is different.

Put in a stern drive!!

teddillard
10 February 2012, 0816
Holy crap I didn't believe you Larry. Those bitches are running some heavy cubes in there:
(Supercharged 1500cc? OMGOMGOMG)


Engine Type In-line
Cylinders 4
Engine Stroke 4-Stroke
Horsepower (bhp/kW) 300 / 223.9
Horsepower RPM 7750
Cooling Water (Open Loop)
Valves 16
Valves Per Cylinder 4
Valve Configuration DOHC
Bore (mm/in) 83 / 3.27
Stroke (mm/in) 69.2 / 2.73
Displacement (cc/ci) 1498 / 91.4
Compression Ratio 8.4:1
Starter Electric
Fuel Requirements Regular
Fuel Type Gas
Turbocharged No
Supercharged Yes
Fuel Injector Yes
Fuel Injector Size (mm) 60
Carburetor No
Carburetion Type Fuel Injected

Richard230
10 February 2012, 0837
Note that it needs the entire ocean to cool the motor. :eek:

larryrose11
10 February 2012, 0855
Ted, Pretty stupid differences huh? Thanks for keeping me honest and fact-checking. I was just going of the top of my head with the numbers.
1.5L? that is pretty big! that show ya why no one really uses the jet drive unless ua have to, the efficency is that bad, like 1/3 or less of a prop.

teddillard
10 February 2012, 0920
Yeah... as we say in Boston, that's "retaahhded". :rolleyes: No wonder they're so frikkin loud. Truth be told, I detest the things, and thought an electric one would be awesomely quiet and fast too.

Nuts & Volts
10 February 2012, 1001
Do it Ted, i double dog dare you

larryrose11
10 February 2012, 1154
You can make an electic one fast, just not with the stooopid water jet. make a stern drive, or a fixed drive. With an actual prop and a 30 HP motor, it will go like hell.

teddillard
10 February 2012, 1208
...AND have extra killing sauce. :O

Brutus
10 February 2012, 1213
This one includes a tranny :cool:

<iframe width="560" height="315" src="http://www.youtube.com/embed/mlZlQfYQDhs" frameborder="0" allowfullscreen></iframe>

mpipes
10 February 2012, 1255
stand-up skis typically use anywhere from 80hp to 120hp and the fast guys for racing are up around 160 to 220hp

Sit down models used to come with 120hp and were built light and nimble so that was enough power for fun around 50mph. Now they're all 900lbs and need 300hp to move 70mph.. Racers are bumping those 1200 and 1500 motors to 500 and 600hp for speeds nearing 90mph.

The 4 strokes straight from the factory are really quiet while running at speed. It's when the racers pull the water box/muffler out that they get gnarly.

elmoto.net user Ross Champion built a ski using an AC-18 or AC-20 kit for a proof of concept. It was powered by thunder sky cells though, and maybe pretty underpowered. Look up CW Eco Sport ES-1 on you tube. By the way he sold the electric package through elmoto.net, it was split up , think I ended up with some of those parts. :)

Anyway you need a ridiculous amount of power if using the jet pump, and you need to have a prop speed of 7000-8000 RPM to get higher speeds, which means either a transmission or a motor rated for high RPM.

teddillard
10 February 2012, 1318
Interesting. That search led me to this video as well. Pretty sad (due respect to the builder).

<iframe width="420" height="315" src="http://www.youtube.com/embed/lawYVI3HUIQ" frameborder="0" allowfullscreen></iframe>

SplinterOz
10 February 2012, 1453
Interesting. That search led me to this video as well. Pretty sad (due respect to the builder).

<iframe width="420" height="315" src="http://www.youtube.com/embed/lawYVI3HUIQ" frameborder="0" allowfullscreen></iframe>

Yea I found that one but decided you could do a better job.

liveforphysics
10 February 2012, 1527
I agree with everything Larryrose said, and would like to add a bit. Hulls have a given power/thrust requirement to work correctly. That jetski is an absolute dog until you get it up on a hydroplane, and it's riding at it's correct design height in the water. If you can't achieve this needed power level, it's going to be sitting low in the water, and it's going to feel like you're riding in a lake of oatmeal rather than water. Hulls that are short and fat like a jetski have massive drag and really poor handling until they reach design speed and get on a plane, and then they start to work well.

If you want to make an electric boat, you want it long and skinny and as light as possible, and like Larry said, you want a prop not a jet drive for any situation where you don't have tons of extra horsepower to burn.

larryrose11
10 February 2012, 1645
It can be done. There are plenty of fast electric boats out there, they are just radio controlled ones.
like this:

http://www.youtube.com/watch?v=iQ-5m5-0KHg&feature=related
it has 2 motors, probably 10 kw each