You can get in trouble arbitrarily changing props and could likely mask one problem with another. Once you get the pad to shaft measurement right, you want the pitch that gives you the motor RPMs at the high end of the operating range. Then start tweaking from there with vents, cup, etc. If I'm wrong, someone please chime in because that's what I have been taught in the short time that I've been in this game.
2015 Seaark 1872 MV CC Etec-90
Two Helix 12 CHIRP SI's, , MinnKota Riptide ST80/i-pilot Link, Bob's Hydraulic
Bitter Gun Owner