I have had a happy troller for five years now on my Suzuki 115 four stroke, 19 ft. center console boat, and I love it. I can troll as slow as 1.2mph. many times I have to speed the big motor up to get it to 1.9 to 2.0 mph which is my favorite speed. I generally steer my boat with my front trolling motor, Minnkota terrova and never leave the driver seat.
The only drawback with the happy troller is backing up. A little harder to control your boat with the flap down, but it is well worth that small inconvenience. Oh yeah, They act a bit like trim tabs for stabilizing your boat at higher speed also
