I have a 17' Tracker bassboat with a 115 Evinrude. For years I have been running 5400rpm at 43.5mph with my OMC aluminium 13 x 19 and 5400 at 47.5mph with my 13 3/8 x 19 Ballistic (gps). I once tried a 13 1/8 x 21 Ballistic but when I trimmed over 5050rpm the prop lost it's bite and just reved...