sorry for the delayed response, work and life got in the way of Boat. To answer your questions, just about everything is 32v on the boat, all pumps, windlass, nav lights and fans and each room has 32v and 12v lights. As for the 12v batteries to the block I can't find a wire but checking with the continuity tester there is continuity from the 12v neg to the engine block.
What started this issues was I switched two things from 32v to 12 volts, the small air compressor for the horn and the inverter. When I did it I just changed the positive wire of each and left the corresponding neg wire connected to the 32v negative bus bar at the power distribution panel assuming the negative of the two systems were connected. For both pieces of equipment when connected to the 32v ground and the 12 volt power with no load they would have the full 12v voltage (anywhere from13 to 14.2 depending on what the charger was doing) but as soon as I turned on the compressor or used the inverter the voltages would drop to anywhere from 9 to 12 volts. If I fired up the main engine everything worked fine. As soon as I moved the negative wire for the inverter and compressor to the 12v neg bus bar the both work perfectly...