This is the company that we buy thrusters from:
http://www.tecnadyne.com/business.htm
They aren't cheap but they are easy to use and have magnetic coupling
from the motor to the prop, so there are no rotating seals to leak.
If you want cheap motors look at electric trolling motors.  For hobby
use, seals or connectors rated "IP 68" or "NEMA 6P" are usually good to
at least twenty feet.

There was a thread here about three weeks ago titled [EE}: Underwater RF
about controlling a submerged model sub.  Basically ultrasonics is the
only way to go long distances like 100's of yards, but echoes make it
hard to use at close ranges.  "RC" rf controls work for short ranges in
fresh water, but not sea water.  In a nonmetallic tank or swimming pool
I would try putting an induction coil around the pool, but I have never
actually done this.

I think there was a group called the "Sub Committee" that had a neat
model sub website.  Unfortunatly that name is a bit hard to search
for...

If I didn't do this for a living I would have more time to do it for
fun.

Douglas Butler (aka Sherpa Doug)
Senior Engineer
Imetrix Inc.
1235 Route 28A
P.O. Box 152
Cataumet, MA 02534-0152
tel. (508) 564-6460
Fax (508) 564-6860
dbutler@imetrix.com


> -----Original Message-----
> From: Scott Beatty [mailto:Scott.Beatty@ECLIPSEAVIATION.COM]
> Sent: Monday, July 30, 2001 4:20 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [OT]: Underwater robots
>
>
> Doug
>
>         I have some ideas for underwater robots that I would
> like to try.
> So now that I know that there is someone on the list that has
> experience
> with Underwater Robots, I have some questions.  What type of
> motors do you
> use for propulsion?  How do you seal motors or points where
> wires protrude
> from an enclosure from leakage or high water pressure or .
> Can ultrasonic
> signals be used to control robots underwater?
>
>
> Thanks
> Scott beatty
>
> --
> http://www.piclist.com hint: To leave the PICList
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>
>
>

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