> Hi Dan,
>=20
>     The boat I have in mind is indeed of the "unsinkable" type ... At =
first
> I thought of something like a Plexiglass barrel with a motor inside =
whose
> shaft would be connected to an off-center mass which would make the =
barrel
> rotate creating enough drag to get it moving in the water. That would =
be
> pretty much unsinkable but rather hard to steer. Also, it would =
require a
> large radius to allow for a sufficient number of solar cells around =
it.
>=20
>     So, the model I have in mind at this moment looks more like a =
sailboat.
> No mast, no propeller, no rudder and no keel either. I figure than =
anything
> protruding from the boat is at risk of getting broken by a ship, a =
rock or
> whatever and that a propeller or a rudder is doomed to get jammed in =
algae
> or floating trash. It will be made of 2 shells of 1/4" Lexan suction =
molded
> around a styrofoam shape containing a PIC, GPS, digital compass , =
batteries,
> motors and perhaps somekind of RF stage. Two turbines go through the =
boat
> from bow to stern, sucking in water from the front of the boat and =
spitting
> it out at the back. Instead of a rudder I plan on having a sideways
> propeller inside a cavity at the front of the boat. The weight =
(batteries,
> pumps,electronics) is distributed in the bottom of the ship while the =
top
> part is covered with solar cells under the Lexan shell with a window =
for the
> GPS receiver and eventually an antenna.

Nice with the propulsion...
Here's a better idea for the steering:

Use a single pump-system to suck in water, but then split the stream =
into 3 tubes.
These three tubes go out one go left, one center and the last to the =
right.  All at the back of the vesel.
Now you need some sort of shutter mechanism to open/close the 3 tubes.  =
There are about a thousend of these that require very little power.  =
These have a very low stopping ability, but you don't need much =
pressure.
Now the boat can steer :-)

So what do you think ?
This system allows for the cleaning solution of backwash, and a high =
efficiensy pump system would be quite possible to find.  Just select one =
that can handle salt water :-)

I must say:
Your project inspired me alot!  And if you allow I would like to try =
something similar myself.  Mabe see if I can find some of those shutters =
and alike :-)  This is just about the most interseting project I have =
come across :-)

But I don't see how you can get the GPS system cheap enough though...

    KreAture

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