Testing Prop Pitch

SeñorGar · ‎08-03-2016

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E30DPSL on a 12 foot 600 pound aluminum runabout operated by a 200 pound skipper:

As the video shows this boat is under propped with the supplied 3x10.3x12. Duing the run I am adjusting the trim up and down (bounce and no bounce) to find maximum speed and RPM with the supplied 3 blade prop.

Max RPM should be 5750 so I have purchased a 4x10x13 and will test it in a week when the rain stops. Hoping for a 300 rpm drop, ability to stay on plane at lower speed/rpm and getting up on plane sooner.

A second video will follow.

BluewaterBill · ‎07-14-2011

SeñorGar wrote:
Max RPM should be 5750 so I have purchased a 4x10x13 and will test it in a week when the rain stops.

Your engine operating range is from 5500 to 6000 rpm, the optimum range between 5500-5800 rpm.

"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. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with 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.

SeñorGar · ‎08-03-2016

Looking good with the extra blade and inch of pitch

4 Blade max RPM.jpg

5700 rpm WOT down from 6000-6100.

BluewaterBill · ‎07-14-2011

Is acceleration better with the 4-blade ?

"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. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with 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.

SeñorGar · ‎08-03-2016

Sorry for not responding sooner Bill. Somehow I missed your response and question.

I did not feel any improvement in acceleration with the 4 blade and slight pitch increase.

With subsequent testing I discovered it had a tendancy to cavitate on acceleration and quick turns. I have since sold that motor and replaced it with an E60DSL.

This does raise the question as to why the cavitation with no other changes to the boat or motor? Taking a completely uneducated guess, if stern lifting was at play as advertised maybe it was too much lifting ???

BluewaterBill · ‎07-14-2011

I think you both asked and answered your own question, plus the difference in individual blade shape may have played a part.

"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. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with 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.

Testing Prop Pitch

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