posted 01-18-2013 10:12 AM ET (US)        

I have spent the past year trying to find the correct propeller for my 1997 Outrage 20 after repowering with a 2012 E-TEC 175hp outboard. I was having a difficult time finding a propeller that would allow me to reach my optimum RPM of 5500-5600. I would like to summarize my findings into a single post. All my testing was done in similar conditions with a total estimated vessel weight of 3900-4100lbs. Speed is gps, RPM is NMEA 2000, mpg is from my Lowrance display of engine data. All data is a 2 run average.

The BRP Viper 14.75x16 was borrowed and in about 9.5/10 condition. Holeshot was very good, but cruising in chop left me always manipulating the throttle to maintain speed. The Viper 16 did not seem to have very good grip. WOT RPM was just in my optimum range. Midrange acceleration was good. This prop had poor low speed docking control. Propeller seemed to provide bow lift. On a lighter boat I think this prop does a very good job. It serves my friend well on his 1978 Mako 19.

The OMC SST 15x17 was borrowed and appeared to be in about 7/10 condition, with no major dings. This is the older SST which has a Stainless steel finish and the propeller has a very noticeable exhaust gas diffuser ring. Holeshot and cruise were decent, and this prop felt very good at all speeds. Midrange acceleration was adequate It had decent low speed docking control. WOT RPM was a bit low, but speed was
decent. Propeller seemed neutral in lift.

The Mercury Mirage Plus 15.75x15 was purchased used and is in about 8/10 condition. Holeshot and cruising are very good with this prop. This prop had no issue with pushing a load of 5 scuba divers and 8 tanks although it probably wasn't too good on the engine. Midrange acceleration was lackluster. Low speed docking control was excellent. At cruise, the Mirage Plus had decent grip, but needed to be tucked in for tight turns. WOT RPM was slightly low, and oddly this prop was the slowest of the bunch at 38mph. I feel I need to re-test this propeller because I think I should have been able to squeeze better numbers out of it. Weight is 12.8lbs

The BRP Rebel 15.75x15 was brand new and came with my E-TEC. At first glance the Rebel appears to be a Mirage Plus copy. I would imagine it is based on the Mirage Plus and then tweaked some. Blade shape is similar, but the Rebel has a noticeably fatter trailing edge with aggressive cupping and more blade rake. Performance was very similar to the Mirage
Plus, but had better fuel economy, and better WOT speed. The Rebel also had far superior grip to the Mirage Plus. Holeshot was slightly slower than the Mirage Plus. Docking control was similar and this prop also weighed 12.8lbs.

The Mercury Enertia 15x15 was purchased new after not obtaining my optimum RPM with other propellers. It has a reputation of being faster and easier to turn than the Mirage Plus of the same pitch. This propeller lived up to its reputation and exceeded my expectations. The first thing I noticed is that this prop actually makes the Mirage Plus
look small. The blades are larger and the barrel is longer. The Enertia has highly swept or skewed blades with a very large amount of rake along with aggressive tip cupping that adds to the effective rake. This prop is NOT lighter than the Mirage Plus even though Mercury propaganda suggests that it is a light weight prop. It tips the scales at 13.6lbs, nearly a pound more than the Mirage/Rebel. The first thing I noticed on the water with the Enertia was the holeshot was hugely improved over any prop I had tried. I found myself pulling back on the throttle much sooner to settle into cruise speed. RPM stayed constant while running through the chop much like the Mirage/Rebel. Midrange acceleration was
also the best that I had experienced and reminded me of the performance I had with the 2.5L carbureted 200 Mercury previously on the boat. Low speed planning was not quite as good as the Mirage/Rebel but still very good. Low speed control and docking was also just slightly below the Mirage/Rebel. WOT speed was the fastest at 43mph. WOT RPM with the Enertia was slightly over my optimum, so loaded down it will serve me well. Fuel economy was just a bit below the Rebel, but I suspect I will use more fuel compared to the Rebel because this prop inspires me to want to "drive it like I stole it." I can't really say enough good about this prop, it really feels like it made my boat come alive, I am not sure if it is just because I am hitting the RPM that the motor was designed for, or if it is the design of the prop.

Anyway, I plan to keep the Enertia with the Mirage Plus as a backup, and sell the Rebel mostly because it is in better condition and is worth more. Other props I tested were a Viper 19 that was good, but held my RPM way down, and a vengeance 19 that was terrible in every way, and a Mirage 17 that was decent but held the RPM down too much too. I hope that someone finds this useful, I know I enjoyed reading this type of info while I was searching for my ideal prop.

Prop Cruise RPM MPH MPG Slip% WOT RPM MPH slip %
Enertia 15 3500 24 3.8 12 5675 43 2
Rebel 15 3400 26 3.9 1 5325 41 0
SST 17 3600 28 3.8 12 5300 41 11
MirageP 15 3200 24 3.6 4 5350 38 7
Viper 16 4000 28 3.6 14 5500 41 9

*Cruise speed is just determined by best fuel economy. Also only the Enertia and Rebel were tested after removing the bottom paint which appeared to not have much effect other than maybe .1mpg improvement.

I hope the format looks OK on this.

posted 01-18-2013 12:48 PM ET (US)            

As you have discovered, the low pitch sizes of the Enertia have a LOT of blade area, the result of their large diameters. As the pitch increases, the Enertia has a much smaller diameter and less blade area.

While the MIRAGEplus also haa increased diameter with lower pitch, the change in blade area seems to be less.

On my boat, which uses 19" pitch propellers, more or less, the 19" pitch Enertia also yielded more RPM than the MIRAGEplus. However, it did not match the speed or fuel economy; the 19" Enertia was 1 MPH slower at WOT than the 19" MIRAGEplus propellers I use.

The Enertia does have very good grip and when it begins to loose it, it does so gradually rather than ventilating all at once like the MIRAGEplus sometimes does.

posted 01-18-2013 01:03 PM ET (US)            

The results you have with the ENERTIA are very interesting. I do not recall such a good comparison of the ENERTIA to so many other propellers. Thanks for the information. Your comments about the propellers are also appreciated. There is certainly a different feel to different propellers, and this is not reflected in just a table of numbers. Again, thanks for those comments.

A visual comparison of the ENERTIA and the MIRAGEplus can be seen at

posted 01-18-2013 06:18 PM ET (US)            

I find that first-hand reports and actual data are much more interesting than speculation. Too often I see a unfortunate tendency for Expert fear-mongering, that is, someone who is regarded as expert on a subject begins to intentionally create fear, uncertainty, and doubt about various topics.

posted 01-18-2013 09:29 PM ET (US)            

The correct conclusion is that the 15" Enertia is a better propeller than the 15" MIRAGEplus for an Evinrude E-TEC 175 equipped 1997 Outrage 20, operated as James operates his.

If anything, this thread demonstrates what I have said over and over through the years: A propeller that works well on one boat/motor combination may not work as well on another boat/motor combination. The MIRAGEplus is the best propeller I have found for my own boat, and I have tested twelve different sets of propellers.

If it were as simple as one model of propeller being better than another model, the inferior one would no longer be made. Clearly, Mercury has no plans to stop manufacturing the best selling high horsepower propeller in the world, the MIRAGEplus.

posted 01-18-2013 10:10 PM ET (US)            

Using jimh's Crouch's Speed Calculator: http://continuouswave.com/cgi-bin/crouchcalc.pl

I find that for my boat estimating the weight at 3900lbs, and horsepower at 175, and speed at 41mph, I get a hull factor of 193.
If I keep the same hull factor of 193 and weight of 3900lbs, the calculator suggests that it would require about 194hp to push the boat to 43mph.

That is a gain of 19hp that would be needed to turn the Rebel 15p in order to propel the post-classic Outrage 20 to 43mph.

I have read people saying that using the Enertia is like bolting on 30 extra hp, if that were true I should have seen 44.2mph. I am a bit disappointed that I did not see 44.2mph.