Evinrude New Zealand

PROPELLERS

Choosing the right propeller is the single most important decision you can make to get the best performance from your boat and outboard! Propeller choice can affect boat top speed by as much as 5 to 10 MPH. It also has a direct effect on acceleration, cornering, pulling power, and fuel economy. With some boats, you may need to change propellers for different activities, such as high speed cruising, water skiing, or carrying heavy loads. Using the wrong propeller in any of these applications will not only hurt performance, but could also cause engine damage.

BASIC PROPELLER TERMS

A. LEADING EDGE. 
The edge of the blade closest to the boat. 
B. TRAILING EDGE: 
The edge of the blade farthest from the boat. 
C. BLADE TIP: 
The point on the blade farthest from the hub. It separates the leading edge from the trailing edge. 
D. BLADE ROOT: 
The area where the blade attaches to the hub. 
E. BLADE BACK: 
The side of the blade closest to the boat (low pressure side). 
F. BLADE FACE: 
The side of the blade opposite to the boat (high pressure side). B 
 
 
DIAMETER 
Diameter is the width of the circle described by the tips of the rotating blades. Propeller diameter determines the amount of power a propeller can apply to the water—how much load the propeller can push. Generally, heavy loads require larger diameter propellers while small, fast boats are more efficient with a smaller diameter. However, diameter is not usually a critical option when choosing a propeller. Focus instead on propeller style and pitch. 
PITCH 
Pitch is the theoretical distance a propeller will travel in one complete revolution. For example, a 14-1/2 X 21 propeller would ideally move 21 inches forward with each revolution. In practice, the actual distance travelled is less than the pitch because of “slip” which is necessary to produce thrust. Lower pitched propellers are like the lower gears on a car or bicycle. They create less forward travel with each revolution. A low pitch allows engine RPM to build up quickly, which gives faster acceleration and more pulling power. This works well for heavy loads, but results in slower top speeds. Higher pitched propellers are similar to high gears. They create more forward travel with each revolution. A high pitch puts more load on the engine, which reduces low speed pulling power and acceleration, but usually provides more top speed.
RAKE 
Rake is the angle the blade tip tilts away from the gearcase. The angle is measured on a line extending from the center of the hub through the center of the blade. Rake can be either flat or progressive. Progressive rake means that the rake angle increases with distance from the hub. Most propellers have between 0º and 20º rake. High rake propellers tend to lift the bow of the boat. On fast, lightweight, V-bottom boats, a high rake propeller should increase speed by reducing the amount of wetted hull surface. When operated partially surfacing, high rake propellers reduce the amount of water being thrown off the blade by centrifugal force as the blade leaves the water. This allows high rake propellers to work more effectively in these applications. Tunnel boats and other air entrapment type hulls may become unstable when using a high rake propeller. In these applications, a propeller with less bow lift would be a more appropriate selection.

CUP 

Cup is the small curved lip added to the edges of some propellers. Cupping acts like a seal on the edge of the blade. It keeps water on the high pressure blade face from flowing around the trailing edge to the low pressure area on the blade back. This reduces ventilation and slipping, especially when operating in disturbed or aerated water. Propellers with cup excel in sharp turns and applications where the engine is mounted higher than normal. Cupping also allows the outboard to be trimmed higher for more bow lift. Cupping the tips of the blades increases the effective rake, adding to the bow lift capabilities of the propeller. Adding cup to the trailing edge of the blades has the effect of increasing pitch. As a result, you can expect a slight loss of engine speed (150- 300 RPM) when cup is added. However, the additional cup may allow the propeller to work at a higher transom height. Raising the motor will reduce drag on the gearcase and will often recover the engine speed.

VENTILATION 
Ventilation is the result of air bubbles from surface air or exhaust gases being drawn into the blades. These pockets of air make a propeller lose its bite or thrust. Your RPM may climb wildly, yet you may not gain or lose speed. This is most common with high transom mountings, extreme trim settings, or sharp turns. To help prevent ventilation, the outboard has an anti-ventilation plate directly above the propeller. For most applications, this plate should be within an inch above or below the bottom of the boat. On a high-performance boat, this rule does not necessarily apply. The anti-ventilation plate may be several inches above the boat bottom. Water testing is the best way to determine the correct engine mounting height. Cupped or high performance propellers help minimize ventilation.
CAVITATION 
Cavitation is caused by a disturbance of the water flow in front of the propeller. An irregularity in the boat bottom or gearcase, a misplaced transducer or speedometer pickup, or even a loose rivet can cause this problem. Cavitation begins when a disturbance creates a low-pressure area in the water flow. As speed increases, the low pressure intensifies enough to vaporize (boil) some of the surrounding water. When the vapor bubbles approach a high pressure area, they collapse, releasing energy and causing damage. The results of cavitation usually appear as burned areas on the gearcase or propeller blades. If the damage is substantial, performance is lost and the propeller should be replaced. In addition, the cause of the disturbance should be repaired to prevent further problems.

PROPELLER OPTIONS

ALUMINUM

GENERAL PURPOSE & ECONOMY

  • Lowest cost and good value
  • Precision casting provides  great strength and long life
  • Cupped blades
  • Recommended for runabout, deck, flats/bay, multi-species, and twin-log pontoon boats
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ALUMINUM
GENERAL PURPOSE & ECONOMY

  • Lowest cost and good value
  • Precision casting provides  great strength and long life
  • Cupped blades
  • Recommended for runabout, deck, flats/bay, multi-species, and twin-log pontoon boats

VIPER™ TBX™
RUNABOUTS & GENERAL  RECREATION

V6 – Standard & Counter Rotation
V4 – Standard Rotation
Versatile 3-blade performance
Excellent balance of speed and durability
Recommended for runabout, deck/flats, multi-species, offshore and pontoon boats

HYDRUS™
PONTOON BOATS

  • Ideal upgrade from aluminum
  • Fast planing 3–blade versatile prop
  • Cupped blades

RAKER® H.O.
BASS & HIGH PERFORMANCE

  • Set the highest stands in top speed performance
  • Maximizes the superior power and torque of the Evinrude E-TEC G2 engine
  • Superior bow lift
  • Vented hub for faster acceleration
  • Recommended for multi-species (fiberglass only), bass, and sport runabout

ROGUE™
SMALL RUNABOUTS & FLATS BOATS

  • Provides extra stern lift
  • Stays on plane w/minimum RPM
  • Custom high luster finish

CYCLONE™ TBX™
OFFSHORE CRUISING & RUNABOUTS

  • V6 – Standard & Counter Rotation
  • Enhanced performance propeller
  • Stays on plane with minimum RPM
  • Less vibration and improved fuel economy
  • Recommended for runabout, deck, flats/bay, multi-species (Aluminum only), and offshore boats

REBEL® TBX™
OFFSHORE & CRUISING

  • V6 – Standard & Counter Rotation
  • Designed & engineered for  efficient midrange cruising hub system
  • Use on offshore boats, large  runabout, & pontoon boats

RX4®
TRACTION & ROUGH WATER

  • Masters the power curve of the Evinrude E-TEC G2 engine
  • Optimized for traction and rough water
  • Delivers superior bow lift on larger boats and does not slip in turns
  • Recommended for runabout/deck, bass, multi-species, offshore and triple-log pontoon boats