When I owned a W-52 in a 15 ton steel cutter
, I considered "cruise" to be about 2,100, which gave about 5.8 knots in flat water
(we sailed in not flat water), turning a fixed 18 x 13 3-blade prop.
I can't recall
the power curve...it will be in the manual...but it would be typical of me to seek a "sweet spot" that cost me as little amount of diesel
as I could get away with and still get home by dark, etc. As I recall
, at 2000 rpm/5.6 knots, this drank about .90/U.S. gallon/hr.
Hope this helps. It's all from memory as I swapped the Westerbeke
out for a Beta 60 and a feathering prop.