Evinrude E-NATION, for those dedicated to water, power, fishing and fun
Reply
Captain
Posts: 85
Registered: ‎05-11-2015

115 HO & Bow Lift

Just purchase a 2nd boat (for my son) RT188 Ranger w/ a 115 hp HO.  Hole shot is descent and top end is right about 46mph with two men.  The boat runs extremely flat.  Would a 4 blade Rogue help in your opinions?  Currently running a 21 pitch 3 blade Viper.

Ranger Ryan
Admiral
Posts: 5,697
Registered: ‎07-14-2011

Re: 115 HO & Bow Lift

Chances are the Rogue would allow for better acceleration and out-of-the-hole performance but may not be as fast as the Viper. What rpm does the motor achieve at WOT ? 

***************


"There is never just one thing wrong with a boat";
                                                 -- Travis McGee, main character in a book series by John D. McDonald


***************
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. If you elect to do it yourself, be sure to use caution, common sense, and to observe all safety procedures in the vicinity of gasoline, moving engine parts, high temperature components, heavy items, and electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation or a technique, enlist the services of a factory trained technician.
Captain
Posts: 85
Registered: ‎05-11-2015

Re: 115 HO & Bow Lift

6300 RPM WOT at 45.7 mph GPS

Ranger Ryan
Admiral
Posts: 5,697
Registered: ‎07-14-2011

Re: 115 HO & Bow Lift

6300 rpm is overrevving the motor, it is probably on the rev-limiter plus using extra fuel and oil from being above the factory redline. Install a larger pitch prop to get the revs between 5800-6000 for best results.

***************


"There is never just one thing wrong with a boat";
                                                 -- Travis McGee, main character in a book series by John D. McDonald


***************
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. If you elect to do it yourself, be sure to use caution, common sense, and to observe all safety procedures in the vicinity of gasoline, moving engine parts, high temperature components, heavy items, and electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation or a technique, enlist the services of a factory trained technician.
Captain
Posts: 85
Registered: ‎05-11-2015

Re: 115 HO & Bow Lift

 I have a 21 pitch viper currently.  As I see it, I have two choices.  

-Viper 22 (staying with a 3 blade) or

-Rougue 21 (moving to a 4 blade)

Both options I listed are the largest pitch offered.  I know this is trial and error.  What would YOU do in this situation?

Ranger Ryan
Admiral
Posts: 5,697
Registered: ‎07-14-2011

Re: 115 HO & Bow Lift


RangerRyan wrote:

 I have a 21 pitch viper currently.  As I see it, I have two choices.  

-Viper 22 (staying with a 3 blade) or

-Rougue 21 (moving to a 4 blade)

Both options I listed are the largest pitch offered.  I know this is trial and error.  What would YOU do in this situation?



RangerRyan wrote:

6300 RPM WOT at 45.7 mph GPS


 

 

Now I am confused. Is the 6300 at 45.7 mph with the 19 or the 21 inch prop  ?     

 

What is your engine complete model number that is printed on the serial number sticker?  

 

Which tachometer do you have and has it been compared to a laptop with the Evinrude diagnostic software for accuracy  ?  


 

***************


"There is never just one thing wrong with a boat";
                                                 -- Travis McGee, main character in a book series by John D. McDonald


***************
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. If you elect to do it yourself, be sure to use caution, common sense, and to observe all safety procedures in the vicinity of gasoline, moving engine parts, high temperature components, heavy items, and electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation or a technique, enlist the services of a factory trained technician.
Captain
Posts: 85
Registered: ‎05-11-2015

Re: 115 HO & Bow Lift

BluewaterBill, sorry I confused you.

The boat has a Viper 21 on it from the factory.

Model # A115GHLAFH

Engine serial # 05472972

Engine Build date 7/2016

i am way over RPM'd at WOT

Ranger Ryan
Captain
Posts: 84
Registered: ‎09-12-2016

Re: 115 HO & Bow Lift

Generally when you put an engine to WOT and start trimming up, there is a point where trimming up  any further doesn't increase boat speed  but your RPM still increases.

 

The RPM at the trim point where the boat no longer incresaes in speed is generally the WOT RPM.

 

Is the 6300rpm at this point or trimmed all the way up?

Admiral
Posts: 5,697
Registered: ‎07-14-2011

Re: 115 HO & Bow Lift

[ Edited ]

 

 

 

Your data does not work right.  A 115 with a .5 gear ratio turning a 21inch prop 6300 rpm would theoretically do about 63 mph. That calculates to a 27 %  slip since you report a 45.7 mph top speed.

 

  Either your tach is not accurate or the propeller may have been  " worked "  as long as you are using a GPS for the speed results. 

 

The motor may be mounted too high or perhaps trimmed out too far and the prop is ventilating. See if the speed improves or the rpms go down and the speed stays the same if you trim it in somewhat.

 

The  ...H model engine you have shows a .5 gear ratio in the parts book. The following article shows how to determing the gear ratio in case you have a different gearcase installed.

 

 

Gear Ratio Calculation - http://www.evinrudenation.com/owner-zone/by-the-numbers-gear-ratio-determination-and-speed-calculati...

***************


"There is never just one thing wrong with a boat";
                                                 -- Travis McGee, main character in a book series by John D. McDonald


***************
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. If you elect to do it yourself, be sure to use caution, common sense, and to observe all safety procedures in the vicinity of gasoline, moving engine parts, high temperature components, heavy items, and electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation or a technique, enlist the services of a factory trained technician.
Captain
Posts: 85
Registered: ‎05-11-2015

Re: 115 HO & Bow Lift

BluewaterBill, I will run the boat again tomorrow evening and report back

Ranger Ryan