Building a "Aquascooter"

Hello friends of "boatdesign.net",

i am from germany and i have a very exotic hobby.

Three years ago, i bought me an "Aquascooter" (link: OLX South Africa is no longer available http://images02.olx.co.za/ui/18/42/63/1329055137_314593963_1-Pictures-of--Aquascooter.jpg).

Its a machine where you can hold your hands on it and it will turn you through the water when you push the throttle (of the carburetor of the two stroke engine). It has a fuel tank (circa 1 litre) and a air tank, that it can swim on the water surface.
A capped propeller is used to power the machine and the person.

A long time later, i tinkered with the idea of doing a selfmade aquascooter with more power.
I used a lawnmower engine with 6 hp and "developed" a own aqua jet with pvc tubes (escape pipes).
A pump impeller should suck the water from the underground and push it out on the rear hole of the pump case.
You can show a lot of pictures of the project in the following link:

boote-forum.de - Das Forum rund um Boote http://www.boote-forum.de/showthread.php?t=90512&page=6


I used a bodyboard as "body" of the whole aquascooter and two stabilizer to compensate the high balance point of the lawnmower engine.

After 4 month developing and handicraft work, i tested the scooter on a lake.
And the result was: too less power

The problem was the pump impeller i think...it didnt transport water with the required pressure.


Now i am ready to build a new Aquascooter. The Aquascooter "version 2" with a (hopefully) better efficiency/power on water.


So i really need your help....
I thought about very different drives....a model aquajet is too small.
A jetski jet is too big.
A lower unit of a outboard engine is to difficult to mounting it (rough surface: rabbets...)
A propeller shaft is too long and now i have a idea.

I wanna use a propeller of an outboard engine (5 hp) and put it in a metal case (like the picture of the link: http://www.boatdesign.net/forums/at...ngine-conversion-outboard-rangajamman-009.jpg).

this is (from my view) the best engine solution, if the shaft of the lawnmower engine goes vertical through the board.


The name of this kind of power unit is named "Veth-Jet".


Now my question:
What dou you think about my idea and what can you give me as "idea of improvement"?


Thank you very much!

Greets from Germany,
Johannes

 

Too much water friction everywhere is what I see, you may have reached the speed limit? Dragging a semi submerged human body through water has a lot of friction, so doubling power may only increase speed by 10%? Outboard motor props will be very inefficient (water turbulence within the cage) compared to the inside impeller of a jet drive in the drawing. Maybe try a design like that used by scuba divers in their electric scooters?

Porta

 

use the impeller off a large truck engine water pump, cheap and more efficient than a propeller for this application. a regular prop is actually more efficient, but in this application would be a very large hazard to the user and everyone around him.

 

Hello,

The problem is to clogging up the electric engine (like a diving scooter).
The other problem is, that i wanna drive how long i want.
And charging batteries is very annoying...
..and of course, i love gas engines!


Can you give me a example picture of the truck water pump impeller?
I searched and it gives a lot of different designs of the impeller.

The question is: What is the difference between my pump impeller in the link of my first aquascooter and a truck water pump impeller?

Here is another link frommercury from a jet device on a outboard lower unit:
http://www.mercurymarine.com/_media/images/engines/jetdrives/jet_drive_illustration.gif

thanks

 

others name these "Pump Jet"...
http://www.schottel.de/marine-propulsion/spj-pump-jet/
has been done and is already there for years... look at the function principle and you get an idea of how the casing should look like...
you need to press the water in and accelerate it via a sort of jet nozzle like thingy (for no better word)...

edit:
so petros suggestion to use a pump impeller is spot on because these apparatus are way closer to a pump than anything else...
why not trying to find one fluid pump the right size and modifying it?

 

Comments Below:

Hope this helps.

Porta

 

There are plenty of pumps you can use for that particular purpose, but most are sold with a 5 hp (or more) engine attached to it. They are used to fill, clean and empty swimming pools, supply water to large gardens or fire fighting.

Just an impeller , a well designed cover and a bottom plate. Attach a piece of pipe to the radial output port and you're in business.
Such pumps you may find wherever they service small agricultural machines. Not in the shop but probably in the yard behind it, waiting for the "Sperrmüll" collector.

 

here is a rebuild kit for a truck water pump. the impeller is on the left. You can find a junk one and use the parts, when the seal goes on the pump assembly they usually throw out the pump. As CDK notes, there are lots of pumps that use a similar impeller, I just thought a used water pump out of large truck engine would be cheap, about the right size, and easy to find almost anywhere there are trucks. it sucks in the center and the high pressure end is the perimeter of the vanes. a simple housing will work, or you can use the truck water pump housing. all you need is a coarse screen over the inlet to prevent fouling.

www.hh-autoparts.com/wp-content/uploads/2013/05/DAF-Truck-Water-Pump-Repair-Kit-8-DF017702-.jpg

 

Hamilton Water jet started out with the same idea and it did actually work well
even though the pump was not designed for the purpose it was used for. For a more efficient propulsion effect it was found that the intake water needed to be discharged into the lower pressure of the atmosphere, similar to the effect of surface propulsion which a water jet is.
The only requirement to push a boat forward is to move as much water rearward from the boat at the highest velocity possible.

 

Doesn't the intake direction contribute?

 

Exactly my idea too Tom Kane. Outlet water jet above the water line. Than again i learn a jet is a jet, in water, air or space action gives reaction. Thought it had to do with slamming what Hamilton jets found. Imagined pulse slamming but was told a jet is a jet, one of Newtons laws. do have to read up on that. Doenst seem to rhime

 

Building an "Aquascooter"

Everything you can do to improve the design to work better contributes.
Such improvements as screens to keep out debris will lower efficiency and help block the intake flow and finally all flow. The speed of the boat moving forward defines where the water flow will come from but generally from all directions.

 

Hi, i'm from Italy and i'm a design student. I'm building a 3D Model of an hybrid aquascooter (both for sea and ground). For now i'm creating a prototype of this vehicle but i need more informations and tips about the materials to use and its functioning. Thank you very much.

 

@holocope I think you will get a better response to your request for information if you start a new thread about your aquascooter, rather than asking questions on other existing threads.

When you start your new thread, please provide as much information as possible about the aquascooter, including any drawings / sketches that you have produced so far.

 

Okay thanks, I'm going to start a new thread