The trolling speed on my ranger boat is too high accept. with a rev 4 19 pitch prop; the slowest I can get it is 3.2 mph @ 680 rpm. this prop maxes out at 5850 rpm. I was looking into a bay pro prop. what pitch should I start at? bay pro 11 or 111? Or would a three blade pro work better. I need to get the motor troll as slow a possible with those rpms.