The new racing Pegasus RF 27 S of Top Line and a brand new Optimax 300 XS is a combination with which the Ribadventure team will take part in international races and they were waiting for us at Thermaikos Gulf for our first test.
We had the opportunity to keep in our hands two very interesting 4-blade propellers which are designed to run at very high mounting heights.
A Hydromotive Quad IV 15 ½" x 27" and a Signature Eagle 4 15" x 27".
Intimidator Quad IV propeller
The Hydromotive Q-IV is designed primarily for racing boats, but also for boats with sport character, and fits very well into both single and double ventilated step bottom hulls. It is characterized for its exceptional mid-range acceleration, its excellent throttle response and it achieves high speeds.
This propeller is available in both right-hand and counter-rotation and its pitch ranges in every inch from 19″ to 35″.
Signature Eagle 4 propeller
The Eagle 4 propeller is characterized by its excellent throttle response, the very small torque on the steering wheel and especially the stunning performance at WOT.
The Eagle 4 is an Over-Hub Exhaust propeller the blades of which are attached directly to the smaller and solid tube that fits over the propeller’s shaft. This means that the exhaust gases run over their blades, a fact that can have negative effects on hole shot but beneficial ones at very high speeds.
We were still in the break-in procedure of the engine during of which it is not allowed to exceed 5400 rpm and thus we restricted to analogous measurements.
Looking the above data we can see that the Hydromotive propeller:
- gave us clearly higher speeds in the whole rpm range.
- showed smaller slip numbers, due not only to its greater diameter but also because the Eagle 4 is a propeller with a small and solid tube in which the exhaust gases go through directly between their blades.
Regarding the behaviour of the mentioned propellers:
- The amount of thrust of Eagle 4 was lower because of its ventilation due to the exhaust gases and also to its smaller diameter
- The Hydromotive propeller got the rib on plane faster and gave greater accelerations
- The feeling of the steering torque was about in the same degree
- The Eagle 4 presented less stability during the ride (chine walking) and was required much more skilful handling of the steering wheel
- The Hydro presented greater stability and was holding the bow in better running attitude.
It is obvious that Hydromotive propeller and its design features fit better to the Pegasus RF 27 S hull compared to Eagle 4.
Having two propellers of different philosophy but of the same pitch, this test was also interesting for another reason: to see if over-hub props can run faster at WOT than thru-hub ones!
This, however, we will find out in the next test after the end of the engine’s break-in procedure.