Re: Waterjet Propulsion? [Not just AIP anymore <g>]

["Sean Walinga" <swalinga@telusplanet.net>]

>        Is waterjet propulsion for a relatively *slow* moving object like
>a personal submarine practical?  I know it's used on some speed
>boats, and on "jet ski" type watercraft.  Seems like I've read or heard
>that waterjet propulsion isn't practical for slower moving vehicles.

I have looked into this one a little. The air to fluid ratio in a jetski waterjet is
crucial. The air is mandatory in the vaccum created within the waterjet. Also; the
jet thrust creates a turbulence in the water located behind the jet. This is
difficult to design around if this trailing water is in contact with your sub. The
net effect is a craft that doesn't track properly and also shudders...

The air needed is also an issue in a sub...

>        It seems to me that a waterjet system would eliminate the
>problems [if any] associated with sealing a through-hull drive shaft
>turning a propeller.  It would also eliminate any dangers a spinning
>prop would have on anyone swimming near the sub.

The waterjet still needs the driving shaft. This means that you still have the
"problem".

If safety is an issue, you may consider a caged propellor. Like the air fan in your
home (except different).

ttfn
Sean