If I remember my ''antiquities'' the Sailmaster dumps the cooling water into the shaft housing, not ''out the back'' so you wont see it. If my memory serves well, there are 4 teeny exit holes in the housing and you ''may'' see mist exiting.
The sailmaster has an easily replaceable impeller.
With the sailmaster you should once yearly separate the power head from the ''tail'', pull the output shaft and apply grease to the mating splines of the cranksaft. The only thing that will kill this type of OB is the splines on the crankshaft/power shaft will corrode away ... if you dont keep them routinely greased with a good waterproof grease.
I have a smaller version - over 20 years and with NO internal wear.