Hello,

     Today i had an idea for a battery/motive power concept.
I would like to get some feedback and also see if anyone would like to experiment with the idea.  As I was researching the idea I came across something very similar called a "flow battery".  The idea is to put a group of dissimilar metal plates parallel to each other  creating a galvanic cell into the sea.  Thereby powering the cell with an inexhaustible source of ions from the sea water.  Then  use said cell to power a dc boat motor creating forward motion and also a flow past the plates without having to use a pump to create laminar flow.  With the flow passing by the plates there should be minimal oxidation accumulation on the plates due to the constant flow washing the plates clean and renewing the electrolyte in the cell.  I have drawn a  of a proof of concept to get peoples minds wrapped around the principle that I described above, but with a twist... turning a batter/motor using the lorentz force to turn the shaft. 

Sounds really interesting.
Use what mother nature already has to offer, in abundance even.
There's enough to go around for everyone, including big oil et al.
Me likes :-D

if an iron nail is dropped into an aluminium boat , dissimilar metal eats the other  ..... the iron eats a hole .
 steel hull ships have zinc anodes bolted on the sides for the same reason , the zinc gets eaten .
steel structure wharf has a DC / transformer to stop the steel rusting in the sea .

so if your looking for a large surface area plate , the hull is 1 option ....but  make sure its ot the sacrificial plate :0)

If you used the boat hull as a plate that would be suicidal and also inefficient.  You would need a multi plate system where all the plates are parallel to the flow of water maybe at the stern that can be raised and lowered as needed to replace the sacrificial parts and also to stop the cell from eating itself when not in use.

A small scale boat should be a good proof of concept. How about a catamaran?You could lower the plates down to the water level in between the two floats.You could use it in conjunction with a sail when there is no wind you can lower the plates.

You'll need to understand electrochemistry also. Michael Faraday attempted the same thing by putting electrodes into the Thames river thinking that the river's flow was cutting the earth's magnetic field but electrochemistry wasn't so well defined and instruments weren't that good back then.
12.   The Dynamo Process
Scroll down to "The Waterloo Bridge experiment".

Along the same lines, gases are also considered fluids in this context so you might think about plates under water and plates above water in the air arranged similarly to the diagram at the following link that I posted in your other thread. Scroll down too "Kelvin's Thunderstorm".
Homebrew Electrostatic Generator