overrev the johnson

[clyde53]

i have a 16' crestliner with a 70hp johnson outboard it currently has a 13x19 prop on it which is allowable according to the johnson book however at full throttle is sounds to be working extremely hard and has a low top end speed, I recently got a great deal on a 14x13 prop which is also allowable for this motor. I do not have a tachometer, YET, and i am concerned I might overrev the motor not having a clue what the rpm's are and dropping to that drastic of a pitch should i be concerned or am i just a worry wart. It might not help the top end speed but it will definately decrease the laboring motor and help for fuel economy. Just dont want to overrev

Get a tach. Otherwise you will just be guessing

[Kevin B]

I agree. Tachometer is the most important instrument in my boat. Prior to having one installed, I was guessing at rpm - - and I was way off. I also use it for trolling. I seldom look at MPH when trolling becauseI know that "x" lure, at 850 rpm runs "x" feet deep on "x" pound test line and that my speed is probably "x". At 1000 rpm, "x" lure is . . . and so on. Best $150 I ever spent on my boat.