By Thomas P.

The Tempest plus is a 3-blade propeller that is designed for boats over 5 meters and recommended for outboard engines over 135hp. It is available in 17, 19, 21, 22, 23, 24, 25, 26, 27, 29 pitch and is considered as one of the fastest propellers.

Tempest plus με την - Revolution

The Revolution is a 4-blade propeller and is available in 15, 17, 19, 21, 23, 25 pitch while quite recently intermediate pitches have also been presented. The Mercury mentions that “the Revolution is the 4-blade cousin of the legendary 3-blade Tempest plus”, because of the common characteristics of its design.

Indeed, at first glance it seems that these propellers, apart from the number of blades, they have the same characteristics:

  • same diameter of 14 5/8΄΄
  • similar blade shape
  • similar surface area in each blade
  • same amount of cup, which extends and covers the tip of the blade
  • similar rake

But a closer look will reveal some small but important differences:

Tempest plus με την - Revolution

  • The tube of Revolution is 2 cm longer
  • The tip of the Tempest’s blade extends at the same level with the rear edge of the tube while at Revolution we see that the rear edge of its tube extends beyond the end of its blade’s tip
  • The inclination of the blades backwards - rake - is greater in Revolution by about 7 degrees
  • The width of the blades, on their central portion, is less by about 1 cm in the Revolution
  • The length of the Revolution’s blade is 1 cm longer and is due to its higher rake, which leads to the increase of the blade’s length so as to maintain the same diameter with the Tempest plus
  • The slight differences in the length and width of their blades, either in favour of one or the other, may have as final result almost the same surface area of each blade, but their function is different

Tempest plus με την - Revolution

These slight differences in the characteristics of the Revolution, plus of course the additional blade which among others increases the total surface area of its blades, make it:

  • run better at elevated engine heights and of course it can be mounted higher than the Tempest plus
  • perform better in loaded boats because it is a stern lift propeller while Tempest is not. That’s why, the Tempest performs better in light loads
  • offer shorter time to plane and hold the boat on plane at lower speeds
  • faster at low and medium rpm, while the difference in their speed increases in favour of the Revolution as the loads increase
  • have better fuel consumption at mid-range rpm
  • work softer and smoother, without vibrations, offering better handling of our boat, greater stability and better throttle response
  • have remarkable grip in rough seas and a better bite in the water
  • provide greater lift of the stern, thus helping the acceleration of the hull, particularly in overloaded boats at stern
  • have lower ventilation rate at the entire range of speeds, as well as at sharp turns, even when we trim up the engine at its higher limits
  • have smaller slip numbers in the whole range of revolutions

Tempest plus με την - Revolution

Tempest plus με την - Revolution

On the other hand, the Revolution causes greater load on the engine, since the additional characteristics make it “heavier” for the engine and thus reduces its rpm.

Tempest plus με την - Revolution

When we switch from a 3-blade Tempest plus to a 4-blade Revolution of the same pitch, we should expect a reduction of our engine rpm at about 150-200 rpm. Still, we can also raise the engine higher on the transom, because the Revolution runs better at elevated engine heights without sacrificing performance, retaining the same rpm without having to decrease the pitch.

...keep Ribbing!