2. CONTENT
• Introduction To Navigational Aids
• Importance Of Navigational Aids
• Requirements Of Signals
• Types Of Navigational Aids
• Some important terminologies
3. INTRODUCTION
• These are the objects or devices which aids the
travellers in navigation or for determining the safe
course past hazard to navigation.
• It can be of both fixed type or floating type.
• They also serve to warn the navigators about
dangers and assisting them by providing safe
navigation while approaching the high sea.
• These fixed or floating objects includes lights, light
ships. Buoys, day beacons, fog signals plus
electronic aids to navigation such as radio
beacons.
4. IMPORTANCE
• It enhance the safety and can acts as good safety
barriers.
• It helps to improve safety at seas.
• For finding and safely navigating a narrow channel
in a wide expense of water.
• It is also help for mariners to determine their
position with respect to land or any navigational
hazard or hidden danger.
5. REQUIREMENTS OF SIGNALS
• Compels attention
• It permits time for easy response
• Makes it meaning clear at glance
• Commands respect
6. TYPES OF NAVIGATIONAL AIDS
• There are two types of navigational aids:
Depending upon structure:
1) Fixed structures 2) Floating structures
Depending upon service and visibility:
1)Coast approach light station 2)Obstruction light
station 3)Approach channel lighting 4)Harbour light
signal
7. FIXED TYPE STRUCTURES
• In this category, the navigational aids are in the
form of:
1. Navigational on piers, wharves, dolphins etc.
8. FIXED TYPE STRUCTURES
2. Beacon lights on breakwaters, shores etc.
A beacon is an intentionally conspicuous device
designed to attract attention to a specific location. A
common example is the lighthouse, which draws
attention to a fixed point that can be used to navigate
around obstacles or into port.
9. FIXED TYPE STRUCTURES
Types of navigational beacons:
a) Radar reflectors
b) Radio beacons
c) Sonic and visual signals
a) Radar reflectors:
Radar reflectors is an object-detection system that
uses radio waves to determine the range, angle and
velocity of objects.
10. FIXED TYPE STRUCTURES
b) Radio Beacons:
• In navigation, a radio beacon is a kind of beacon, a
device that marks a fixed location and allows
direction-finding equipment to find relative
bearing.
• Radio beacons transmit a radio signal that is
picked up by radio direction-finding systems on
ships, aircraft and vehicles to determine the
direction to the beacon.
11. FIXED TYPE STRUCTURES
c) Sonic and visual signals:
• Visual beacons range from small, single-pipe
structure to large lighthouse or light station and
can be located on land or water.
• There are also used of lights in navigation of ships
at harbour like fixed light,Occulting light, Flashing
light and coloured light.
12. FIXED TYPE STRUCTURES
3. Light Houses:
• Light tower structures are the tall tower structures
build on a masonry or reinforced concrete.
• A marine beacon light lantern is provided on the
top of the tower.
• A tower is divided into no. of floors.
• The lower floors are used as service, stores and
living rooms for maintenance and working of light-
house.
• The towers are generally erected on points along
the shore to guide vessels to a nearby ports.
13. FIXED TYPE STRUCTURES
3. Light Houses
• These light houses are also constructed on reefs,
shoals or other points of danger to vessel.
• The towers should be strong enough to withstand
heavy wave action.
• Foundation of tower depends upon the
characteristics of the soil but generally thick bed of
concrete is provided on hard or rocky bed.
• Piles or caissons may be used on marshy locations.
14.
15. FLOATING TYPE STRUCTURES
• There are two types:
1. Light Ships
2. Buoys
1. Light Ships:
• A lightship is a ship which acts as a lighthouse.
• In locations where it is not practical to build light-
houses, small ships displacing about 500 tonnes are
used for the purpose.
• Light ships can be fully manned to small unmanned
ones with automatic light and fog signals.
16. FLOATING TYPE STRUCTURES
• The first lightship was posted in 1820 in United
States in Elizabeth river.
• The propulsion of lightships is either steam
powered or diesel powered.
• The maintenance cost of light ships is very high as
compare to light houses.
17. FLOATING TYPE STRUCTURES
2. Buoys:
• These are small sized floating structures, generally in
the form of cylindrical cans and drums. They are
moored at the bottom of the sea.
• It is used to mark channels and obstacles like rocks,
shoals, wrecks and other dangers to the navigation.
• They convey information to the navigator by their shape
and color, by the characteristics of visible and audible
signals or the combination of two or more such
features.
• Buoys have top marks and exhibit light.
• They also have fitted radar reflectors and audio signals.
18. FLOATING TYPE STRUCTURES
• Types of Buoys:
According to the US Coast Guard classifies the
various types of floating buoys as:
1. Can Buoys:
A buoy with flat topped cylindrical shape above
water, above the left side of the channel leading into
a harbor.
19. FLOATING TYPE STRUCTURES
2. Spar buoys:
these are the upright wooden poles or tubes of steel
which are often used to mark obstructions.
20. FLOATING TYPE STRUCTURES
3. Nun Buoys:
This buoy is of red metal made up of two cones joined
at the base and usually marking the starboard side of
the channel approached from the sea.
21. FLOATING TYPE STRUCTURES
4. Spherical Buoys:
A buoy of which the upper part of the body (above the
waterline), or the larger part of the superstructure, is
spherical.
22. FLOATING TYPE STRUCTURES
5. Lighted Buoys:
• These buoys carries batteries or gas tank and have
a framework that supports a light.
• A fixed light maybe on either a green or red
channel buoy.
• A regular interval light flashing at not more than
thirty flashes per minute may be on either a green
or red buoy.
23. FLOATING TYPE STRUCTURES
6. Bell buoys:
• Bell buoys have flat tops, surmounted by a
framework supporting a bell.
• A buoy equipped with a bell rung by the motion of
the sea, warning shipping of shallow waters.
24. FLOATING TYPE STRUCTURES
7. Mooring Buoys:
• Mooring buoy is a floating structure which is used
to moor vessels either cruise ships, fishing boats,
cargo ships, or private ships while in deep water or
shallow water.
• The buoy is moored to seabed by using chains or
ropes, known as mooring.
25. FLOATING TYPE STRUCTURES
8. Emergency Wreck Buoys:
• Emergency wreck buoy is used to warn of a new
wreck which has not yet been listed in maritime
documents.
• The buoy is expected to be deployed for the first
24-72 hours after the wreck occurs.
• The buoy is painted with 4, 6 or 8 vertical stripes of
alternate yellow and blue.
• In addition it may have the word "WRECK" painted
on it.
26. Some Important Terminologies
1. Buoyancy: This is the upward force exerted on the
immersed or partially immersed body by a fluid.
Buoyancy= Weight of the volume of fluid displaced
2. Buoyancy factor: This is the weight of the
substance in sea water divided by the weight of same
substance in the air. It is expressed in percentage.
3. Net Buoyancy: This is the equivalent to the weight
of water.
Weight in air-weight of sea water displaced when the
net buoyancy becomes negative the object sink.
27. Some Important Terminologies
4. Float: This is an object which is constructed primarily
to provide net positive buoyancy.
5. Buoy: This is a float which is used as a major positive
buoyancy component in the system. A buoy system is
comprised of both buoys and floats along the mooring
lines and instruments.
6. Luminous Flux: This is the light given by a light source
or received by a surface irrespective of the direction in
which it is distributed.
SI Unit of luminous flux is Lumen
7. Lumen: A lumen is the flux emitted through a unit
solid angle from a uniform point source of one candle.
28. Some Important Terminologies
8. Illumination: This is luminous flux incident on a
surface per unit area.
9. Luminous Intensity: This may be defined as the light
giving power of a lamp in any given direction.
10. Luminance: This may be defined as the light is
reflected from a unit projected area of an illuminated
surface in given direction.
11. Pilotage: This is an arrangement on which any ship
bound to or from a foreign port is required to take on a
pilot when entering or leaving port.
Upon entering the harbor, a pilot boat pulls up alongside
the vessel and the port boards the ship to supervise the
remainder of the ship’s vessel.
29. Some Important Terminologies
Rates for this service are usually charged in
accordance with the amount of maximum draft of the
vessel.
12. Pilotage Unit: It represents the rate of the
pilotage service.
Pilotage Unit= LxBxD/10,000
Where L= Overall length of the vessel
B= Extreme breath of the vessel
D= Depth to the uppermost continuous deck
