The design of an MHD propulsion boat is illustrated in Fig. 2. It consists of a rudimentary boat with a channel down the center through which water passes and is accelerated for the propulsion. The top and bottom of the channel have electrodes. The boat must be sufficiently large in order to float its power source, in this case six 9-V batteries in series. Permanent magnets are situated along the channel to provide the external magnetic field.

Figure 2.

It is important that the magnet poles are located on the sides of the magnet and not on the ends. This creates a magnetic field perpendicular to the current direction and results in the water being pushed down the channel. This is illustrated in Fig. 3 and is emphasized by the use of cylindrical magnets, which are less efficient but easier to visualize. Note: If the current direction is instead chosen to flow upward, the pole orientation of the magnets will have to be reversed.

Figure 3.