Use pressurized water as manuevering thruster?

Of course !
Didn't changed my mind !
These belts are the best solution for home made devices.
Reduction ratio can be adjusted, no vibration transmitted and medium cost
Sorry if my first post wasn't clear enough

Almost all you dreamed to know about belts... is here
http://www.sdp-si.com/D260/D260cat.htm

 

Apologies for not reading the whole thread.

What about triple bilge pumps or similar?

 

The thread seems to have run out of steam. I would be interested to hear more about the results of the home made trials.

Great informed discussion - it has certainly helped me

What I took away from the discussion is that ideally we need a large diameter exit and ideally a reversable pump to reduce the valve and pipe work. For recreational yachts the answer is starting to look like a prop in a tunnel in the bow....

On large boats where there distance between the exits is large maybe there is some benefit from using a single pump instead of several thrusters.

 

Actually I witnessed the trial of water cannons on a tug recently. The system is designed to produce 1300Cu.m at 12bar to operate through 3 cannons. Do not know the bore but the throw with 30 degrees elevation was about 150m.

The 32m long vessel moved at 1 to 1.5 knots into a slight breeze. They have measured 2 kts in calm conditions.

It will take about 600kW to produce that flow and pressure so demonstrates the poor performance of a high speed jet as a slow speed thruster.

You are right about the large diameter. For slow speed maneuvering you ideally move a lot of water slowly if you want efficiency.


Rick W

 

Update from Willdo

If you haven't been to the Willdo site lately, check this out...

http://www.willdo.eu/index.php?subject=180

Here is exactly the configuration I was talking about. It simply sucks water from one side and pushes it out the other. The size seems limited at this point, hence the "Mini" name, but I think the principal is sound. I doesn't suprise me that they developed the pump themselves. After completing Par's "Pump Thrust 101 Course", I didn't find any off-the-shelf equipment that seemed to fit the bill.