I have a 1 1/2 in jabsco
impeller pump driven by the crankshaft pulley on my 120 lehman
. It has it's own mechanical clutch
that you engage by hand. The pump is primed by the fresh water system, I have never had to rebuild
this pump in 6000hrs of cruising (except for new impellers every 2 yrs). Pump was installed when the boat was commissioned in 1978. Takes up very little room and since the hoses are hooked up all the time it is immeaditly available if the main eng is running. If time is of the essence this in my opinion is the way to go.