by terrybaker
(dunn nc)
have a 1998 bayliner trophy. 18 ft cuddy cab with a 150 Yamaha. boat will not jump on plane. with the old mariner 120 it would jump right up on plane. prop size on it was a 12.5 X 19. the Yamaha has a 14 X 15 and struggles to get on plane. also max RPM's on Yamaha is only 4300 RPM's and the top speed is 30 MPH by GPS. The old mariner would run 35 MPH. so what size prop do I need to get the same performance or better from the Yamaha? I have tried 14 X 19, 14 X 17, and the 12.5 X 19. can someone help?