When it was decided to not proceed with the build of the first hull, a second hull was quickly built and tested.  This hull was based on two waterproof COTS cases.  These cases were modified to allow wired in and out with waterproof connectors.  A superstructure was cut out of industrial plastic to hold the two cases and the motors in place.  The lower chamber made of PVC pipe is the primary battery compartment.  In this design, the control electronics are housed in the front case and the motor controllers are housed in the rear case.  Keeping these two sections separate helps reduce the  amount of noise generated by the motor controllers on the compass.  As the last picture shows, the hull proved to be too difficult to waterproof.  It too was abandonded.