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Author Topic:   ENERTIA v. MIRAGE

jimh posted 07-01-2009 07:23 AM ET (US)
Tom Clark took some very nice photographs of two Mercury propellers, a MIRAGEplus and an ENERTIA. These photographs show the general shape of the propellers and how they compare. First we look at them in profile:

MIRAGEplus in profile view.

ENERTIA in profile view.

Overlay of MIRAGE and ENERTIA. The ENERTIA is more transparent.
These views show that the ENERTIA has a higher rake angle and its exhaust tube is longer.
Now we look at the propellers in plan view:

MIRAGEplus in plan view.

ENERTIA in plan view.

Overlay of MIRAGE and ENERTIA. The ENERTIA is more transparent.
Thanks to Tom for sending these images. I look forward to your comments.

jimh posted 07-01-2009 07:38 AM ET (US)
Note about the images: I don't think these images are precisely aligned and there might be a bit of distortion in them. However, they do very nicely convey the general shape of each propeller, allowing for a good comparison.
L H G posted 07-01-2009 11:51 AM ET (US)
Props pictured are same pitch?
It's interesting to see how much propeller techonolgy and materials have improved at Mercury. The Mirage Plus looks obsolete. Check mercurymarine.com and you will see both props are designed to the same performance/application specifications, but look how different they look.
The Mirage Plus was the prop Mercury uses as the baseline for the improved "HP" you get from an Enertia and it's new lightweight alloy.
TransAm posted 07-01-2009 11:54 AM ET (US)
Crudely measured on my computer screen says they are the same pitch.
Perry posted 07-01-2009 12:43 PM ET (US)
I have used both on my current boat/motor set-up and I have to say that for my application the Enertia is by far the better propeller. It has become my everyday prop now.
Tom W Clark posted 07-01-2009 01:22 PM ET (US)
Yes, both propellers are 19" pitch models.
No, the photographs are not perfectly aligned. I took them hastily a few years ago when the Enertia was new.
The MIRAGEplus is used as a point of comparison to the Enertia not because the Enertia is meant to replace it but because there are so many MIRAGEplus propellers out there; it is one of the most successful, popular and numerous propellers ever made.
jimh posted 07-01-2009 07:37 PM ET (US)
The photographs are great. You can't find information like this anywhere else. Thank you, Tom, again, for taking them and sending them.
I would like to follow up on the ENERTIA propeller material. It was claimed to be a break through in metallurgy that would be patented. It has been several years since it was announced, and, as far as I can tell, there is no patent. Anyone with information about the ENERTIA alloy patent please comment.
jimh posted 07-02-2009 07:44 AM ET (US)
Using the photographs, I measured the rake angle of the two propellers:
Tom W Clark posted 07-02-2009 08:43 AM ET (US)
The photographic overlay is particularly enlightening. Here we can see how different the Enertia really is and how is packs a lot of blade area into a prop with a relatively small diameter,
The leading edge of the blade of the Enertia emerges from the hub perpendicular to it instead staring as a sweep. But it quickly turns backward and extends quite a ways.
This is a characteristic of what are sometimes called "elephant ear" props which were used on very old motors and still used on some high thrust kickers. Yet the sweep of the sweep of the blade is extensive.
In contrast, the MIRAGEplus has a conventional shape along the lines of the venerable OMC SST and the Mercury Laser II with its leading edge emerging from the hub already seeping back and forming a nice round blade tip and returning to the hub almost, but not quite square to it.
The MIRAGEplus is a design of subtle alterations from early designs. It performs well on numerous types of boats and seems to be a very good balance of different propeller qualities.
It has been made, and continues to be made, in great numbers because of its versatility.
For the record, and because I always get asked this question, the difference between the MIRAGEplus and the original MIRAGE (apart from hub differences) is that the MIRAGEplus has more cupping than the MIRAGE.
In fact an old MIRAGE can effectively be converted into a MIRAGEplus by a knowledgeable prop shop.
The old MIRAGE is faster on some boats than the MIRAGEplus because of this reduced cupping.
jimh posted 07-02-2009 09:18 AM ET (US)
I found Tom's use of the term "Elephant ear" to describe the blade shape of the ENERTIA propeller to be quite interesting, as that exact same notion occurred to me when I saw the overlay. Of the two blade shapes, the ENERTIA clearly most resembles what we would describe as an Elephant's ear. Curiously, in the past the term "Elephant ear" has been used in a somewhat derogatory manner to describe propeller shapes which were not particularly attractive or worthy of note. Yet here we have a return to the old-fashioned Elephant ear blade design, but it is promoted as being an advance in technology.
Peter posted 07-02-2009 09:57 AM ET (US)
Here is an overhead picture of a VIPER propeller made by OMC or BRP.
i177.photobucket.com/albums/w231/Whaler-Fleet/Public/ViperPropeller-1. jpg
Note its use of swept back blades like the ENERTIA. As compared to the ENERTIA, the blade tips on the VIPER seem to be narrower or more pointed.
This variation of the VIPER propeller has existed for about 10 years. This propeller tends to produce a faster top speed than the OMC SST II propeller or the BRP REBEL propeller. The REBEL is similar in shape to the MIRAGE PLUS.
By the accounts I've read and also from personal experience the mid range fuel efficiency of the VIPER is not as good as the SST, REBEL or the MIRAGE PLUS. Also, the VIPER propeller blades seem to be rather thick for a stainless steel propeller, thicker than the SST propeller blades or MIRAGE PLUS blades. Given the use of the swept back blades, I'm curious to know how the ENERTIA compares to the MIRAGE PLUS.
Peter posted 07-02-2009 10:05 AM ET (US)
I make the additional observation that the ENERTIA blades appear to be swept back more than in the case of the VIPER. If one were to draw a straight line substantially bisecting the blade along its length and extending the line out past the blade, it appears that the linie would not intersect with another blade in the case of the ENERTIA.
If one drew the same line for the VIPER, the straight line would intersect with the trailing edge of the adjacent blade.
aussiejake posted 07-02-2009 08:04 PM ET (US)
This is a very informative thread. An addition to it would be advantages of changing from the old style VENGEANCE propeller to the more modern blade designs of the MIRAGEplus and ENERTIA. If you lay the VENGEANCE over the MIRAGEplus there is a massive difference in design shape. I call the VENGEANCE blades Micky Mouse ears.
Many people are still running the VENGEANCE and find it hard to justify the hundreds of dollars to change from the old design to the new. The pictures alone tell a story. I for one changed to a MIRAGEplus from the VENGEANCE and was amazed at the difference. Better grip, no cavitation, and better economy at cruise speeds.
I have a 19P from the VENGEANCE in the shed so if you want some pics the same angle as the others let me know.
cheers,
Jake
Peter posted 07-03-2009 10:15 AM ET (US)
I believe that the sweeping backwards of the blades is called "skew". The skew of the ENERTIA is much greater than the skew of the VIPER. The MIRAGE PLUS would probably be characterized as having very little skew.
jimh posted 09-03-2012 11:15 AM ET (US)
Peter--I think you are correct. The ENERTIA blades have more skew.
onlyawhaler posted 09-04-2012 10:52 AM ET (US)
Great thread. I run a 19 pitch MiragePlus on my 20 Outrage. I wonder how a Enertia would compare in getting on plane and top end speed
Sterling
Onlawhaler
jimh posted 12-08-2012 12:18 PM ET (US)
This thread was revived but the topic was then changed to become specific to a particular application. This thread is discussing the ENERTIA and MIRAGEplus visual appearance, and what inferences can be made from them. Now that it has been revived, I would add the following:
I note that an earlier comment was made that the ENERTIA's appearance represents improved technology. I don't understand how to infer technology from the appearance of the propeller blade shape, other than to offer the observation that many modern large ship propellers use very highly skewed blades. There is some evidence of blade skew in the ENERTIA that is not seen in the MIRAGEplus, but the blade skew in the ENERTIA is not nearly as much as seen in modern ship propellers.
The propellers are the same rated pitch, 19-inch. There are clear differences in the rake angle of the blades. As for blade area, we have only a two-dimensional view in the plan view. A good method for comparing blade area is to fit onto a propeller blade a sheet of kraft paper and make an outline of the blade. Cut out the outline and you will have a representation of the blade area. Do this for another propeller. Then you can compare the blade areas with the two cut-out's.
When the ENERTIA was introduced there was much fanfare and attention given to its metallurgy, which was said to allow for blade flexing. This was counter-intuitive for me because blade flexing was previously always mentioned as a negative characteristic. For example, aluminum propellers were said to display blade flexing which caused them to lose pitch and perform poorly. Yet the ENERTIA is said to use an alloy of stainless steel that permits flexing. This has never been quite resolved to my satisfaction.
Russ 13 posted 12-09-2012 06:07 AM ET (US)
As a broad statment, the propeller with the higher rake
is usually better at improving top speed, as the increased
rake improves bow lift, resulting in less boat in the water.
..
The rounder less raked propeller creates less bow lift,
and usually less top end speed.
The rounder blades are usually better in producing reverse
thrust.
Commander Coo1 posted 12-10-2012 02:38 PM ET (US)
Another broad statement about propellers is that shortening the barrel of the prop will increase bow lift. I have read of people cutting down the barrel of a Rev4 to get more bow lift and they did so with good results if im not mistaken. You can see that the Enertia has a much longer barrel than the Mirage. It is longer than any other propeller I have seen.
The Enertia has the reputation of being pretty neutral in lift similar to the Mirage Plus. I wonder if the combination of the elongated barrel and increased rake have cancelled each other out as far as lift characteristics are concerned.
-James

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Author	Topic: ENERTIA v. MIRAGE
jimh	posted 07-01-2009 07:23 AM ET (US) Tom Clark took some very nice photographs of two Mercury propellers, a MIRAGEplus and an ENERTIA. These photographs show the general shape of the propellers and how they compare. First we look at them in profile: MIRAGEplus in profile view. ENERTIA in profile view. Overlay of MIRAGE and ENERTIA. The ENERTIA is more transparent. These views show that the ENERTIA has a higher rake angle and its exhaust tube is longer. Now we look at the propellers in plan view: MIRAGEplus in plan view. ENERTIA in plan view. Overlay of MIRAGE and ENERTIA. The ENERTIA is more transparent. Thanks to Tom for sending these images. I look forward to your comments.
jimh	posted 07-01-2009 07:38 AM ET (US) Note about the images: I don't think these images are precisely aligned and there might be a bit of distortion in them. However, they do very nicely convey the general shape of each propeller, allowing for a good comparison.
L H G	posted 07-01-2009 11:51 AM ET (US) Props pictured are same pitch? It's interesting to see how much propeller techonolgy and materials have improved at Mercury. The Mirage Plus looks obsolete. Check mercurymarine.com and you will see both props are designed to the same performance/application specifications, but look how different they look. The Mirage Plus was the prop Mercury uses as the baseline for the improved "HP" you get from an Enertia and it's new lightweight alloy.
TransAm	posted 07-01-2009 11:54 AM ET (US) Crudely measured on my computer screen says they are the same pitch.
Perry	posted 07-01-2009 12:43 PM ET (US) I have used both on my current boat/motor set-up and I have to say that for my application the Enertia is by far the better propeller. It has become my everyday prop now.
Tom W Clark	posted 07-01-2009 01:22 PM ET (US) Yes, both propellers are 19" pitch models. No, the photographs are not perfectly aligned. I took them hastily a few years ago when the Enertia was new. The MIRAGEplus is used as a point of comparison to the Enertia not because the Enertia is meant to replace it but because there are so many MIRAGEplus propellers out there; it is one of the most successful, popular and numerous propellers ever made.
jimh	posted 07-01-2009 07:37 PM ET (US) The photographs are great. You can't find information like this anywhere else. Thank you, Tom, again, for taking them and sending them. I would like to follow up on the ENERTIA propeller material. It was claimed to be a break through in metallurgy that would be patented. It has been several years since it was announced, and, as far as I can tell, there is no patent. Anyone with information about the ENERTIA alloy patent please comment.
jimh	posted 07-02-2009 07:44 AM ET (US) Using the photographs, I measured the rake angle of the two propellers:
Tom W Clark	posted 07-02-2009 08:43 AM ET (US) The photographic overlay is particularly enlightening. Here we can see how different the Enertia really is and how is packs a lot of blade area into a prop with a relatively small diameter, The leading edge of the blade of the Enertia emerges from the hub perpendicular to it instead staring as a sweep. But it quickly turns backward and extends quite a ways. This is a characteristic of what are sometimes called "elephant ear" props which were used on very old motors and still used on some high thrust kickers. Yet the sweep of the sweep of the blade is extensive. In contrast, the MIRAGEplus has a conventional shape along the lines of the venerable OMC SST and the Mercury Laser II with its leading edge emerging from the hub already seeping back and forming a nice round blade tip and returning to the hub almost, but not quite square to it. The MIRAGEplus is a design of subtle alterations from early designs. It performs well on numerous types of boats and seems to be a very good balance of different propeller qualities. It has been made, and continues to be made, in great numbers because of its versatility. For the record, and because I always get asked this question, the difference between the MIRAGEplus and the original MIRAGE (apart from hub differences) is that the MIRAGEplus has more cupping than the MIRAGE. In fact an old MIRAGE can effectively be converted into a MIRAGEplus by a knowledgeable prop shop. The old MIRAGE is faster on some boats than the MIRAGEplus because of this reduced cupping.
jimh	posted 07-02-2009 09:18 AM ET (US) I found Tom's use of the term "Elephant ear" to describe the blade shape of the ENERTIA propeller to be quite interesting, as that exact same notion occurred to me when I saw the overlay. Of the two blade shapes, the ENERTIA clearly most resembles what we would describe as an Elephant's ear. Curiously, in the past the term "Elephant ear" has been used in a somewhat derogatory manner to describe propeller shapes which were not particularly attractive or worthy of note. Yet here we have a return to the old-fashioned Elephant ear blade design, but it is promoted as being an advance in technology.
Peter	posted 07-02-2009 09:57 AM ET (US) Here is an overhead picture of a VIPER propeller made by OMC or BRP. i177.photobucket.com/albums/w231/Whaler-Fleet/Public/ViperPropeller-1. jpg Note its use of swept back blades like the ENERTIA. As compared to the ENERTIA, the blade tips on the VIPER seem to be narrower or more pointed. This variation of the VIPER propeller has existed for about 10 years. This propeller tends to produce a faster top speed than the OMC SST II propeller or the BRP REBEL propeller. The REBEL is similar in shape to the MIRAGE PLUS. By the accounts I've read and also from personal experience the mid range fuel efficiency of the VIPER is not as good as the SST, REBEL or the MIRAGE PLUS. Also, the VIPER propeller blades seem to be rather thick for a stainless steel propeller, thicker than the SST propeller blades or MIRAGE PLUS blades. Given the use of the swept back blades, I'm curious to know how the ENERTIA compares to the MIRAGE PLUS.
Peter	posted 07-02-2009 10:05 AM ET (US) I make the additional observation that the ENERTIA blades appear to be swept back more than in the case of the VIPER. If one were to draw a straight line substantially bisecting the blade along its length and extending the line out past the blade, it appears that the linie would not intersect with another blade in the case of the ENERTIA. If one drew the same line for the VIPER, the straight line would intersect with the trailing edge of the adjacent blade.
aussiejake	posted 07-02-2009 08:04 PM ET (US) This is a very informative thread. An addition to it would be advantages of changing from the old style VENGEANCE propeller to the more modern blade designs of the MIRAGEplus and ENERTIA. If you lay the VENGEANCE over the MIRAGEplus there is a massive difference in design shape. I call the VENGEANCE blades Micky Mouse ears. Many people are still running the VENGEANCE and find it hard to justify the hundreds of dollars to change from the old design to the new. The pictures alone tell a story. I for one changed to a MIRAGEplus from the VENGEANCE and was amazed at the difference. Better grip, no cavitation, and better economy at cruise speeds. I have a 19P from the VENGEANCE in the shed so if you want some pics the same angle as the others let me know. cheers, Jake
Peter	posted 07-03-2009 10:15 AM ET (US) I believe that the sweeping backwards of the blades is called "skew". The skew of the ENERTIA is much greater than the skew of the VIPER. The MIRAGE PLUS would probably be characterized as having very little skew.
jimh	posted 09-03-2012 11:15 AM ET (US) Peter--I think you are correct. The ENERTIA blades have more skew.
onlyawhaler	posted 09-04-2012 10:52 AM ET (US) Great thread. I run a 19 pitch MiragePlus on my 20 Outrage. I wonder how a Enertia would compare in getting on plane and top end speed Sterling Onlawhaler
jimh	posted 12-08-2012 12:18 PM ET (US) This thread was revived but the topic was then changed to become specific to a particular application. This thread is discussing the ENERTIA and MIRAGEplus visual appearance, and what inferences can be made from them. Now that it has been revived, I would add the following: I note that an earlier comment was made that the ENERTIA's appearance represents improved technology. I don't understand how to infer technology from the appearance of the propeller blade shape, other than to offer the observation that many modern large ship propellers use very highly skewed blades. There is some evidence of blade skew in the ENERTIA that is not seen in the MIRAGEplus, but the blade skew in the ENERTIA is not nearly as much as seen in modern ship propellers. The propellers are the same rated pitch, 19-inch. There are clear differences in the rake angle of the blades. As for blade area, we have only a two-dimensional view in the plan view. A good method for comparing blade area is to fit onto a propeller blade a sheet of kraft paper and make an outline of the blade. Cut out the outline and you will have a representation of the blade area. Do this for another propeller. Then you can compare the blade areas with the two cut-out's. When the ENERTIA was introduced there was much fanfare and attention given to its metallurgy, which was said to allow for blade flexing. This was counter-intuitive for me because blade flexing was previously always mentioned as a negative characteristic. For example, aluminum propellers were said to display blade flexing which caused them to lose pitch and perform poorly. Yet the ENERTIA is said to use an alloy of stainless steel that permits flexing. This has never been quite resolved to my satisfaction.
Russ 13	posted 12-09-2012 06:07 AM ET (US) As a broad statment, the propeller with the higher rake is usually better at improving top speed, as the increased rake improves bow lift, resulting in less boat in the water. .. The rounder less raked propeller creates less bow lift, and usually less top end speed. The rounder blades are usually better in producing reverse thrust.
Commander Coo1	posted 12-10-2012 02:38 PM ET (US) Another broad statement about propellers is that shortening the barrel of the prop will increase bow lift. I have read of people cutting down the barrel of a Rev4 to get more bow lift and they did so with good results if im not mistaken. You can see that the Enertia has a much longer barrel than the Mirage. It is longer than any other propeller I have seen. The Enertia has the reputation of being pretty neutral in lift similar to the Mirage Plus. I wonder if the combination of the elongated barrel and increased rake have cancelled each other out as far as lift characteristics are concerned. -James