Yes, that is a factor. My little 25 hp diesel has only the alternator on the
single Vee belt. The water pumps are direct driven on the rear of the engine
(I think off the timing gear or cam shaft end). However, as part of this
upgrade I am adding a double belt and a belt drive (clutched) emergency
bilge pump..

(it's sure a shame to complicate such a simple engine)

Thanks for the comment.

Steve
s/v Good Intentions