the white is ground, the black should be switched for a manual circuit. the green should be auto if the pump has auto mode built in, otherwise it would hook to a float switch...
if it DOES have a auto mode, understand how it works before connecting the auto wire. it does cause a discharge even when there is no water in the bilge because it senses every few minutes to see if there is water that needs pumping.
its unlikely that pump has an auto mode, but if it does, the manual switch connected to a float switch with a bypass to a manual switch may be the best way to connect it on sailboat.
when connected to a float switch, a timer relay like a beuler BU508TD will allow the pump to stay on for a predetermined amount of time after the float switch is tripped.
this will allow the pump to stay on long enough to pump the water down even after it gets below where the float switch shuts off.... and the pump wont run on and off with the sloshing of the water in the bilge.
hook a light or alarm into the auto circuit so you know when it cycles, and how often so you can look for a problem if it is cycling too often.
the manual switch is necessary to over ride any failures of the auto/floatswitch mode..
