Johnson 9.9 4-stroke prop?

[joepa]

I just bought a Johnson 9.9 4-stroke kicker and it came with a 9 1/4 X 9 in. prop. I haven't had the boat, a 165 Alumacraft Navigator Classic, in the water yet so I don't know how that motor or prop will perform. Any experience or recommendations? Sould I get a different pitch prop?

[southerncomfort1]

I have a older Johnson 9.9 as my kicker and changed to a 4 blade high thrust prop 5 pitch.The high thrust definitely allows me to turn the boat much better then the original 3 blade.I can troll my Ranger 692 down to .6mph on the gps. If I new I was going to be trolling exclusively at lets say 2 mph then I would probably put the original 3 blade back on that is probably a 9 or 10 pitch so I would not have to rev the motor up as much as I would with the 5 pitch to get the speed and use my TM to steer using the copilot.On my boat actually a 7 pitch high thrust may of been better since those times I need to troll well below 1 mph I can use my trolling motor.Hopefully someone with your boat can help you with how there prop pitch on the kicker is affecting there speed.I still would run that motor and prop to see how it trolls down before changing.

[yarcraft91]

I agree- you may as well try the stock prop first and see how it works. I have a 19' fiberglass boat with a 15 horse Mariner (2.0:1 lower unit gear ratio). I replaced the stock 9-pitch prop with a 5.5. Your 9.9 Johnson has a 1.92:1 lower unit gear ratio and you have a relatively light boat. Both the gear ratio and your boat weight will probably lead to your motor pushing your boat faster than my motor pushed mine. Here's what I'd expect from your 9-pitch prop:

You'll have trouble getting to a trolling speed below 1.0, maybe even getting below 1.5 at dead idle. You'll operate in the lower 1/3 to 1/4 of the throttle range for all your trolling. If you ever need to use the kicker to get home (main motor fails- it happens), the 9-pitch prop won't let the motor run close to its max WOT rpm.

I cured all these symptoms by switching to the 5.5 prop. I can troll down to 0.8 and I have more control over trolling speed because I can use a larger amount of the throttle range. At WOT the motor sounds like I think it should.

My advice also is: don't break in that motor by trolling with it. Put it on a rowboat and run according to Johnson's break-in instructions (keep the 9-pitch on it for this purpose). Once the motor's broken in, then go ahead and give it a life of trolling.

[joepa]

As usual some very good advice. I never thought about the break-in period with the standard prop. Hope I remember to put oil in the crankcase! Getting old and probably could be cast for the sequel of Dumb and Dumber.