This document discusses different components of ship propulsion and steering systems. It describes three main types of rudders - balanced, unbalanced, and semi-balanced rudders. It also discusses propeller types, including fixed pitch and controllable pitch propellers. Key factors to consider when designing a propeller are discussed as well, such as shaft revolutions, number of blades, wake conditions, diameter, blade area, and geometry.

1. Rishi
Immanuel
Arief
Piravin
Anmol
Agilan

3. RUDDER AND PROPELLER
3

4. STERN FRAME
4

5. Spectacle Frames and Bossing.
The shaped frames and plating forming the bossing
terminate in a casting known as the spectacle frame
which provides the aftermost for the shaft.
This system totally encloses the shaft withing bossing.
Thus the wetted surface area of the hull is increased
resulting in greater frictional resistance, however no
struts in open water thus total resistance is smaller.

6. Advantages
1) No struts to be damaged
2) Greater protection of the shaft
3) Access to shafts and bearings for a greater proportion
of the length

7. Cast steel frame

8. May be cast or fabricated, particular attention being
paid to the strut section to avoid increase in resistance
and cavitation.
The connections to the main hull are of particular
important since considerable rigidity of the structure
is required.

9. Disadvantages
1. Larger resistance than bossing due to the various
strut each causing eddies thus increasing resistance.
2. The struts are liable to damage if hit by floating
objects.
3. The propeller shafts themselves are more liable to
damage.
4. Access to the bearings is limited to dry-docking.

10. Rudders

11. Types of rudder
The main purpose of balancing rudder is to achieve the reduction
in the torque required of the steering gear.
• there are 3 types of rudders:
balanced: a portion of the blade area is disposed symmetrically
through the rudder height and fwd of stock
unbalanced: blade is entirely aft of stock
semi-balanced: area fwd of stock does not extend to the full height
of the blade aft of the stock – upper portion may be considered
unbalanced and the lower portion, balanced

12. Balanced Rudder
Axle fitted at its turning axis with large area forward of the
axis (25% to 30 %).
Upper and lower bearings are fitted in the rudder.
The bearing consists of a stainless steel bush in the rudder
and a stainless steel liner on the axle.
The stainless steel bush is spirally grooved to permit
lubrication.
Other materials are in use, such as gun metal for liner and
lignum vitae or tufnol for the bush.

13. UPPER
BEARING
LOWER
BEARING
BOLTED PALM
RUDDER STOCK
LIFTING
TUBE
VERTICAL WEB
HORIZONTAL WEB
DRAIN PLUG
RUDDER AXLE
BALANCED RUDDER13

14. Unbalanced Rudder
Full area aft of the axis.
Fitted with upper, mid and lower arms rested on
gudgeons.
At the bearing pintle fitted with hard steel disc
and locking nut.
The ordinary pintle arranged with bush and
locking nut and the locking pintle at the top part
of the rudder secured by locking nut.

15. Turn on pintles and have a small portion of their
lateral area forward of the turning axis (less than
20%).
Commonly fitted on twin screw vessels where most
of it hinged on a body post by pintles and
gudgeons.

16. RUDDER STOCK
HORIZONTAL
WEB
VERTICAL WEB
LIFTING
TUBE
DRAIN PLUG
RUDDER POST
GUDGEON
LOCKING PINTLE
BEARING PINTLE
UNBALANCED RUDDER

17. Semi-Balanced Rudder
Which are very common today.
Have less than 20% of the
lateral area forward of the axis.
Modern ships’s use this design
of ruder.

18. Rudder Pintles
Pintles are found on all 3 types of rudders.
Pintles on which the rudder turns in the ‘gudgeons’
have a taper on the radius, and a bearing length which
exceeds the diameter.
They not only act as ‘hinges’ but also take lateral loads
and transfer them to the frame, thus reducing the
stresses on the stock and coupling.

19. Locking pintles are designed to prevent the rudder
lifting.
Bearing pintles take part of the rudder’s weight

20. Bearing Pintle

21. Locking Pintle

22. Ordinary Pintle

23. The Propeller

24. Propellers
Propellers may have from 3 to 6 similar blades
depending on the design requirements.
It is important that the propeller is adequately
immersed at service drafts and that there are good
clearance between its working diameter and the
surrounding hull structure.

25. Types of Propellers:
Fixed Pitch Propeller
Controllable Pitch Propeller

26. Fixed Pitch Propeller
The blades in fixed pitch propeller are permanently
attached to the hub. The fixed pitch type propellers are
casted and the position of the blades and hence the
position of the pitch is permanently fixed and cannot
be changed during the operation.

28. Controllable Pitch Propeller
In Controlled Pitch type propeller, it is possible to alter
the pitch by rotating the blade about its vertical axis by
means of mechanical and hydraulic arrangement.
This helps in driving the propulsion machinery at
constant load with no reversing mechanism required
as the pitch can be altered to match the required
operating condition.

30. Shaft revolutions. Apart from the direct influence
on propeller efficiency the choice of shaft RPM
depends upon the gearing available, critical
whirling speeds of shafts and avoidance of the
fundamental frequencies of hull vibrations.
Number of blades which influence vibration and
cavitations.
The wake in which the propeller is to operate.
Factors to be considered when
designing a propeller

31. Propeller diameter and hence clearance between
propeller tips and the hull which has a marked
effect on vibration.
Blade area. The greater the blade area for a given
thrust the less likely is cavitation.
Boss diameter. Dictated mainly by strength
considerations
Geometry of the blades, e.g. pitch, camber

32. Propeller cavitation
Cavitation occurs on propellers (or rudders) that
are heavily loaded, or are experiencing a high
thrust loading coefficient.

33. Propeller Polishing

34. Stern Tube
Fitted to provide a bearing for the Tail End Shaft and
so to enable a watertight gland to be fitted at its an
accessible position.
Withdrawal of the tail end shaft is necessary every
three years(four years for ships with two or more
screws) if fitted wit continuous liners or oil glands, in
all other case every two years.

36. Titanic now and then

37. Thank you and have a good day! 