Prop for 115HP Johnson

[Mvannote]

Hello. New to the site.
The wife and I bought a new (to us) boat. We bought a 1996 Sunbird Fish and Ski with a 115hp Johnson that was/in excellent condition with no issues.
Engine has run great until I accidently put some old gas (4 gallons) in the tank and on the same day hit a stump on the Lake. Water was down and shortly after making contact with the stump and idling to investigate, the motor just stalled. So, after some OMC Systematched engine tuneup and new plugs I was able to get it running again.
Now to my prop question. It currently has a 14 x 17 176214 aluminum prop and was wondering if that is a good prop or if there is a better prop I can use. It currently runs around 38 mph with two people on board. Wondering if changing to a different prop would help with mph and/or fuel efficiency.
Thanks for any info.

 

[jimmbo]

Is your engine the 90 degree 99.6 cubic in. Crossflow, or the 60 degree looper? In addition, what rpms are you currently getting at WOT with the 17 in. prop?

 

[Mvannote]

Is your engine the 90 degree 99.6 cubic in. Crossflow, or the 60 degree looper? In addition, what rpms are you currently getting at WOT with the 17 in. prop?

99.6 cu.in. 4 cylinder 90 degree V cross scavenged
Roughly 5000 rpm

 

[jimmbo]

You are right in the middle of the WOT rpm range for that engine which is 4500 - 5500. Is that rpm at optimum trim?
That is a 17ft boat?
A 17" prop is common for that size of boat, but it usually is a 13 or 13 1/4" diameter
Are you carrying any unneeded ballast in the boat? Any idea what the boat and motor weigh?

A lot pf people would just say to drop to a 15" and gain 400 rpm. I prefer to avoid props with less than 17 in of pitch if possible. Blade shapes below 17 start to resemble ones for tugboats rather than speed boats

 

[Mvannote]

You are right in the middle of the WOT rpm range for that engine which is 4500 - 5500. Is that rpm at optimum trim?
That is a 17ft boat?
A 17" prop is common for that size of boat, but it usually is a 13 or 13 1/4" diameter
Are you carrying any unneeded ballast in the boat? Any idea what the boat and motor weigh?

A lot pf people would just say to drop to a 15" and gain 400 rpm. I prefer to avoid props with less than 17 in of pitch if possible. Blade shapes below 17 start to resemble ones for tugboats rather than speed boats

Trim? Yes, I've trimmed it to achieve 38mph and it is a 17' boat.
Unsure of the boat weight but the 115 is just over 300lbs.
Don't carry much on the boat other than little gear and a motorguide.
The prop #176214 is 14 x 17 but the new part number is #765183 and is 13 1/4" x 17.
Ex: https://www.boatpropellerwarehouse....1-4-x-17-evinrude-johnson-rh-propeller-765183

 

[DRSunbird]

I have the same boat but with a 1996 Johnson 112 spl with the same prop that you got. At 5400 RPM’s it runs 43 mph by GPS. Great hole shot and no bouncing when I trim it up. I did have to pick the motor up a couple holes on the transom because I was getting a good bit of spray on both sides of the motor. Since I moved it up , the spray is almost gone and I can pretty much turn it hard and get little cavitation. I’m impressed with this 112 because these sunbirds are fairly heavy boats.
What kind of gas mileage are you getting, when I bought this boat it had trees growing out of it and hasn’t ran in 15 to 18 years.

 

[achris]

That's a nice job, but please don't post in 4 year old threads. Start your own.

Chris.
iboats mod team.