This presentation is about the various types of Propeller use on ship and their functions.

1. TYPES OF
PROPELLER

4. TYPES OF PADDLE
WHEEL

5. FIXEDPADDLE
These are simple and easy to construct. In this type, the paddles are firmly attached
to the wheel. This system requires wheels of large diameter so that they can enter the
water at large angles. Large diameter means low rpm and more weight. This is the
main drawback of this system.

6. FIXED PADDLE

7. FEATHERING PADDLE
In this system, the paddles are attached at the ends of the wheel in such a manner
that the angle of entrance is much larger than that of fixed type. By this principle,
the diameter of the wheel can be reduced.

8. FEATHERING PADDLE

9. Tandempropeller
• In this arrangement, two propellers are mounted on a single shaft
turning in the same direction. Tandem propellers are fixed so as to
reduce loading on a single propeller as it can lead to cavitation. Here
the thrust is divided between the two propellers.
• In normal loading, they are not of much use but in heavy loading, they
produce better loading than a single propeller.
• Generally, size and number of blades are kept the same

10. Tandempropeller

11. Overlapping propeller
• It has the same advantage as a tandem propeller as the load is divided
between two propellers. There are two propellers with their shafts placed
at a horizontal distance less than the diameter of either propeller.
• They have higher hull efficiency because they work in a region of a higher
wake. The advantage over twin screw is that no extra appendage is
required to support and hence the resistance is reduced.
• Sometimes the mutual interaction between the propellers may, however,
result in more cavitation.

12. Overlapping propeller

13. Controllable Pitch Propeller
•In this type of propeller, the blades are not directly
fixed to the boss but attached to separate spindles.
The spindles can be turned about the axis and so the
pitch of the propeller can be altered. These are mainly
used in ships requiring full power at varying speeds
and resistances. These are mainly used in tugs, ferries,
icebreakers etc.

14. Controllable PitchPropeller

15. Advantages over the conventional fixed propeller
• They provide better acceleration, stopping and maneuvering properties.
• Non reversing propulsion machinery may be used thereby reducing its cost, weight
and space occupied.
• At all loading conditions, the full power of machinery can be used.
• The speed of the ship can be varied without altering the speed of the main engine.
• Speed can be directly controlled from navigation bridge.
• It is easy to replace damaged blades.
• Some disadvantages are:
• The control mechanism is very complex.
• It has high initial cost.
• Maintenance costs are also high
•

16. Ducted Propeller
In this type a non -rotating duct surrounds a screw propeller. The gap
between the propeller and duct is very minute.

17. Ducted Propeller

18. These are mainly of two types:
• ACCELERATING TYPE: They increase the velocity of flow of water to
the propeller.
• DECELERATING TYPE: They decrease the velocity of flow of water to
the propeller.
•

19. Advantages of ducted propeller over normal propeller
are:
• Better course stability
• Less effect of load and speed variation on efficiency
• Fewer chances of damage to the propeller
• Improved efficiency at high loading
• Some disadvantages of the ducted propeller are
• More chances of cavitation
• Poor astern performance
•

20. Supercavitating Propeller
• Supercavitating propellers are used when the design criteria of the
propeller are such that cavitation cannot be mitigated. It can produce very
high thrust at same efficiency without cavitation, corrosion and noise.
Ships with high engine power, speed and rpm deploy such propellers. The
back of the propeller blade is covered by vapor filled cavity. There is a
separation of flow on the back at the leading and trailing edge. The main
objective is that the back of the blade should not be in contact.
• These type of propellers have however less blade strength owing to a thin
leading edge of the blade.
• They also don’t work properly at low speeds.

21. Supercavitating Propeller

22. Surface Piercing Propeller
These type of propellers are partly submerged in water.
These are fitted just at the end of the ship rather than under it. The
propeller shaft is just above the water surface. Since no extra
appendages are required the drag resistance is considerably reduced.

23. Advantages of the surface piercing propeller are:
• It requires less power to achieve the same speed as compared to the fully
submerged propeller.
• Cavitation is considerably reduced.
• Since it is not vulnerable to cavitation, they can have low blade area
• Some disadvantages of the surface piercing propeller are:
• Since the blades enter and leave the surface at each revolution, it is subjected
to periodic loading and can lead to fatigue.
• They have very poor astern performance.

24. Contra-rotating propeller
• It uses two propellers placed on two coaxial shafts. The propellers
rotate in opposite directions. It helps to reduce the rotational energy
losses caused in the slipstream.

25. Some advantages of contra-rotating propellers are
• Loading is shared between two propellers and hence cavitation is
reduced.
• Efficiency is higher than a single propeller.
• Less pressure fluctuations and noise

26. Some disadvantages are:
• Greater weight of machinery at the aft
• Complexity of gearing and coaxial shafts
• Sealing of the shafting system is difficult

27. Contra-rotating propeller

28. Azimuth propeller
• An azimuth propeller is a configuration of marine propellers placed in
pods which can rotate at any horizontal angle.

29. Advantages of azimuth propellers are:
• Rudder use is not required
• Excellent maneuverability
• Good astern performance
• Good speed control
• Vibrations are less

30. Azimuth propeller

31. Azimuth propeller

32. This is a video made by MARINE-WORLD on some
basic type of propellers. Hope you all like it.