I have a 26 gm and was wondering if I should have a zinc on the shaft. I only have 1 3/4 of shaft space between the end of the shaft key and cutlass. H and h stated that you need at least 3/16 for waterflow for the bearing....most collars at 1 1/2 which would leave me 3/16. Will I have an issue with cavitation with that setup or would i be better with a prop nut zinc?