RE: [PSUBS-MAILIST] Minn Kota - Thrust

["Wade Carson" <wacarson@interchange.ubc.ca>]

Paul,

You're right, it is Mercedes or some subdivision thereof.  They are called
Daimler Benz or something like that.  The best way to go with fuel cells is
just having a tank of O2 and a tank of H2 and running that directly through
the cell with the only byproduct being pure water.  Unfortunately, they are
not able to market that because people seem to have an odd fear about
sitting on top of a large tank of hydrogen.  Go figure.  Anyways, I think
the idea with the water and the fuel is that the water is first divided into
it's component atoms and then passed through the cell.  I may be wrong on
this but I think if it is possible to find one you might be better off using
a pure cell in a sub because you are less likely to run into another sub and
blow up the neighborhood.  I've actually heard that the tanks are pretty
safe but that it's just a mental thing with people.  I think the pure cell
would be quite a bit smaller and lighter.
Just as a little tid bit, Ballard was originally funded by the Canadian
government to develop the fuel cell as an alternative power source for naval
submarines.  I think the main benefit was that they run almost silently.
NavCAD will not calculate optimal hull shapes for you.  You must input a
resistance based on the hull form characteristics.  It will then calculate
the powering required to achieve a desired speed or the maximum speed based
on a given powering.  It also does a few other neat things like giving a
propeller efficiency based on the parameters you put in for the propeller so
it is possible to get general information on an optimal propeller shape.
But it doesn't do any fairing for you.  You could mess around with inputting
different form coefficients for the hull until you got one with a low
resistance but still enough internal volume, but you could probably do a
better job sketching the thing on a napkin.  There are other programs out
there that will calculate optimal hull shapes but I haven't used them yet.
For the most part I think they use evil things like computational fluid
dynamics as I mentioned earlier.  Unless you really like very complicated
math you probably don't want to go there.  Napkins and windtunnels are still
better in my opinion.  There is no reason NavCAD shouldn't work for
submerged structures.  I would just set the surface interface resistances to
zero.  The program doesn't really care what the thing looks like.  It's
actually not really that complicated, I'm just not that good at explaining
things in this manner.

Wade