The Vetus water cooled Propeller Shaft Seal is unique in that it is a hole in the hull below the waterline that does not have a stop cock. Water from the engine is piped to the rubber bearing and if there is a problem the water could flow into the boat. I am proposing to insert a 15mm Lever full bore Ball Valve, with fabricated reducers to 10mm, which would be connected by hose to the shaft water intake and to the pipe from the engine, and could be turned off if a problem developed.

When running the engine with the boat ashore the water gushes out around the prop shaft - so likely to gush in?

I would appreciate comments as to the likelihood of such a tap being of use or is water more likely to come through the shaft seal than the water inlet? Have there been problems with this item?

What grease should be used? If the tap is fitted should it be wired to the sacrificial anode?