One of the best known propellers for all around use, especially in the field of inflatable boats, is the Mirage plus. Its good performance in many different types of boats and hulls classifies it at the top of preference of many skippers.
Mirage plus is available in a wide range of diameters (up to 16΄΄) and pitch (from 13΄΄ to 29΄΄), it is known for its very good mid-range numbers and is ideal for boats which tend to have their bow high.
We had the chance to compare Mirage plus 14 5/8 ΄΄ x 23΄΄ with Suzuki14 ¾΄΄ x 23΄΄. It was a very interesting test since these propellers have many common characteristics which allowed us to make specific conclusions on the individual characteristics of their design.
Let's look at the common features of these propellers:
- The same pitch
- The same number of blades
- Approximately the same diameter
On the other hand their differences on blade surface, at the amount of cupping and the rake is actually very small. The outer hub of Mirage plus is two centimetres longer and its internal diameter at the exhaust exit is 5 mm larger than of Suzuki's prop.
The most significant difference is the extremely large cupping of the leading edge of the blades of Mirage plus.
We tested the above propellers on a Suzuki 200hp engine which was mounted on the transom of a Top Line 23. The tests took place in the same sea area, at the same time, with the same direction and angles of trim and, of course, with the same load, in order for our measurements to be as objective as possible.
The following are the detailed measurements of both propellers
The Suzuki propeller
- kept the rib on plane at the same rpm with the Mirage plus, while it is giving us one knot more
- gave us faster acceleration till 35 knots by one second
- gave us greater cruising speed at 3500 and 4000 rpm by one knot
- was slightly more fuel efficient at 3500 and 4000 rpm
- gave us higher top speed by two knots
- showed lower slip numbers over the whole rpm range and thus always giving us higher speeds. In the above detailed data we can see the excellent slip rates which at WOT reached only 4.8%
- As far as its behaviour is concerned, it gave us the feeling of better bite in the water, quicker throttle response while it was gripping slightly better. On sharp turns its grip was excellent.,/
- was more fuel efficient from 4500 rpm and above
- gave us more rpm at WOT, but when we trimmed high (3/4) the engine, the higher slip numbers did not allow it to reach higher top speed
- regarding its behavior, it gave us the feeling of softer riding without losing its grip, especially after 4000 rpm, while in sharp turns its grip was very good
- however, behind its slightly lower performance lies a very important advantage. It gave 300 rpm more than the maximum limit of Suzuki's engine. This means that we can try a 25΄΄ pitch Mirage plus, which is slightly smaller in diameter, allowing our engine to drop at 6000 rpm. Therefore it's very likely to get higher top speed, higher cruising speed and so, even lower consumption.
In general we can say that the slightly better performance of Suzuki's prop is due to its larger diameter by 1/8 inch, slightly bigger amount of cupping and its larger blade area.
On the other hand, those above small differences in the characteristics of Mirage plus allowed the engine to increase 200 rpm more than the propeller of Suzuki, thereby allowing matching a higher pitch propeller.
Of course it would not be fare to miss mentioning the excellent design of the hull of Top Line 23 to which the excellent performance of both propellers owes. It is really worth noting that the performance of the particular hull at speed, fuel efficiency, acceleration and soft riding would envy even the larger ribs. This hull marks its own course regardless of the sea state, giving us incredibly soft riding without the slightest attempt of the skipper and the need of handling the steering wheel. The response of the throttle is excellent; the ride is perfectly weighted to the entire range of engine rpm, showing us the ideal riding attitude. It is an inflatable boat that will really fill with smiles and satisfaction any owner.