Ships
are large complex vehicles which must be self-sustaining in their environment
for long periods with a high degree of reliability. A ship is the product of
two main areas of skill, those of the naval architect and the marine engineer.
The naval architect is concerned with the hull, its construction, form,
habitability and ability to endure its environment. The marine engineer is
responsible for the various systems which propel and operate the ship. More
specifically, this means the machinery required for propulsion, steering,
anchoring and ship securing, cargo handling, air conditioning, power generation
and its distribution. Some overlap in responsibilities occurs between naval
architects and marine engineers in areas such as propeller design, the
reduction of noise and vibration in the ship's structure, and engineering services
provided to considerable areas of the ship. This project will look into the
propulsion system with specific emphasis on the shafting system of a vessel
carrying out a detailed design and analysis.
The
shafting system which is part of the propulsion system of a vessel is a major a
component onboard vessel. The shafting system directs the power generated by
the engine to the propeller which then provides thrust for the vessel. Marine
propulsion is the mechanism or system used to generate thrust to move a ship or
boat across water. While paddles and sails are still used on some smaller
boats, most modern ships are propelled by mechanical systems consisting of an
electric motor or engine turning a propeller, or less frequently, in pump-jets,
an impeller. Until the application of the coal-fired steam engine to ships in
the early 19th century, oars or the wind were used to assist watercraft
propulsion. Merchant ships predominantly used sail, but during periods when
naval warfare depended on ships closing to ram or to fight hand-to-hand, galley
were preferred for their maneuverability and speed. The Greek navies that
fought in the Peloponnesian War used triremes, as did the Romans at the Battle
of Actium. The development of naval gunnery from the 16th century onward meant
that maneuverability took second place to broadside weight; this led to the
dominance of the sail-powered warship over the following three centuries.
In
modern times, human propulsion is found mainly on small boats or as auxiliary
propulsion on sailboats. Human propulsion includes the push pole, rowing, and
pedals.
Propulsion
by sail generally consists of a sail hoisted on an erect mast, supported by
stays, and controlled by lines made of rope. Sails were the dominant form of
commercial propulsion until the late nineteenth century, and continued to be
used well into the twentieth century on routes where wind was assured and coal
was not available, such as in the South American nitrate trade. Sails are now
generally used for recreation and racing, although innovative applications of
kites/royals, turbo sails, rotor sails, wing sails, windmills and Skysails’ own
kite buoy-system have been used on larger modern vessels for fuel savings. A ship moves between two mediums (water and
air) hence the increased resistance to motion. To overcome this, a suitable
propulsion system with an effective shafting system should be selected to meet
the specific vessel requirements. By evaluating and assessing the vessel design
and intended operation profile together at an early stage, from a propulsion
perspective, this will ensure that all interfaces within the drive-line,
control and monitoring systems are precisely defined, resulting in the
installation of an optimized, fully integrated shafting system.
The
design and general assembly of the shafting system of a vessel is very crucial
to the successful operation of the vessel. A well designed shafting system,
will reduce fuel consumption and ensure maximum power transfer from the engine
to the propeller. In this report we shall look into the design and fabrication
of shafting system for a vessel carrying out detailed design analysis of the
various components of the shafting as well as make modifications and
improvements of existing shafting systems.
Small,
mechanically-operated shafting are typically fitted in sailing boats and other
small craft. Compact hydraulically-operated shafting, including two-speed
versions, are suitable for pleasure craft and workboats including those for
fishing, wind farm support, and pilot and harbor vessels, while larger models
are specially designed for fast craft such as defense vessels, super and mega
yachts and high-speed ferries. For commercial, ocean-going vessels such as
freighters and tankers, heavy-duty shafting with various power take-off (PTO)
and power take-in (PTI) arrangements can be specified to match medium-speed
diesel engines.
Large
motor yachts, naval, customs and coastguard vessels and fast ferries all
require compact, high performance shafting, most of which are specially
configured to comply with a ship designer’s requirements. These shafting can be
rigged with optional equipment and monitoring systems to meet stringent
environmental and technical specifications where safety, availability and
reliability are of utmost importance.
For
extremely demanding applications in commercial vessels with extended annual
operation. Various non-reversing shafting are also available, with hollow
output shaft, designed for controllable pitch propeller (CPP) operation. The
shafting system on a ship transmits power from the engine to the propeller. It
is made up of shafts, bearings, and finally the propeller itself. The thrust
from the propeller is transferred to the ship through the shafting system. The
different items in the system include the thrust shaft, one or more
Intermediate shafts and the tail shaft. These shafts are supported by the
Thrust block, intermediate bearings and the stern tube bearing. A sealing
Arrangement is provided at either end of the tail shaft with the propeller and
cone completing the arrangement.
The
primary function of any marine engineering plant is to convert the chemical
energy in fuel into useful work and to use this work for propulsion of the
ship. To ensure that this energy generated is effectively utilized for
propulsion, an efficient shafting system is required transfer the power
generated from the engine to the propeller of the vessel. An efficient shafting
system will reduce the energy loss accustomed to energy transfer and reduce
fuel consumption of the main engine. This project looks at the direct drive
shafting system, carrying out a detailed design analysis of the components.
The
aim of this project is the design and fabrication of a direct drive shafting
system of a vessel.
The
objectives of this project include:
1. To
Increase the power output of the shafting system by maximizing the power
delivered by the engine.
2. Selection
of low cost energy efficient materials for the design and construction of a
direct drive shafting system.
3. To
produce a direct drive shafting system model showing the various component
which will serve as an effective teaching aid.
The
shafting system of a ship is a very important part of the ship machinery.
This
project will provide a better understanding of the principle of operation of
the shafting system and proffer methods to increase its overall efficiency.
This
project will focus on the design analysis and construction of the ship shafting
as well as proffer ways to improve the efficiency and reduce energy losses
associated with the shafting system.
The
project is structured so as to present it in a coherent and logical manner. The
following provides a description of each of the chapters within this document:
Chapter
1 presents the introduction to the project which encompasses the
background study, the problem
definition, and the aims/objectives of the project. It also includes the
significance of the project and its scope.
Chapter
2 provides a literature review of the project. Focus on existing direct drive
shafting in the world history, principles used and usage. Also includes all the
research that has been done to provide ideas and specification as a guideline
to produce the design.
Chapter
3 describes the experimental setup and methods used to design and construct the
direct drive shafting system, focusing on proposed design process, product
design specification concept Measurement and Evaluation, and provides a
recommendation and conclusion.
Chapter
4 of these project gives description of tests carried out on the shafting
system and provides the results of these test in accordance to the parameters
and theories been used. Hence there shall be a discussion of the end result of
these project and its viability.
Chapter
5 will hence be the conclusion of these project as well as analyzing the
limitation and making necessary recommendation pertaining to these project
work.