Just another thought on DR's comment. Unless you want to be continually testing your boats voltage at your wires, using the "natural voltage" setting will show instantly what the current voltage is.
When I originally mounted my d/r's I checked the output and it was O.K. Later that year I was having unusual problems catching fish. After I mounted my B/B, it immediatly showed a reading of 1.700. It took a while to locate the culprit (a d.c. plug filled with water, on an aluminum boat).
Now at the very least I can check my voltage at the flip of a switch.