ISOLATED DANGER MARKS
Isolated Danger marks are erected on, or moored on or above, isolated dangers of limited extent which have navigable water all round them. The extent of the surrounding navigable water is immaterial: such a mark can, for example, indicate either a shoal which is well offshore, or an islet separated by a narrow channel from the coast.
Topmark
Black double-sphere topmarks, disposed vertically, are a very important feature of Isolated Danger marks and are carried whenever practicable.
Colours
Black with one or more red bands are the colours used for Isolated Danger marks.
Shape
No significance is attached to the shape of Isolated Danger marks, but in the case of a buoy, a pillar or spar buoy is used.
Light
A white flashing light showing a group of two flashes is used to denote an Isolated Danger mark. The association of two flashes and two spheres in the topmark may help in remembering these characteristics.
Retroreflectors
One or more white bands, letters, numerals or symbols of retroreflective material are used for unlighted Isolated Danger marks in the Standard Code.
One or more pairs of blue above red bands are used in the Comprehensive Code.
SAFE WATER MARKS
Safe Water marks are used to indicate that there is navigable water all round a mark. Such a mark may be used as a centreline, mid-channel or landfall buoy, or to indicate the best point of passage under a fixed bridge.
Colours
Red and white stripes are used for Safe Water marks, and distinguish them from the black-banded danger-marking marks.
Shape
Spherical, pillar or spar buoys are used as Safe Water marks.
Lights
A white light, occulting, or isophase, or showing a single long flash or Morse code (A) is used for Safe Water marks, when lighted. If a long flash (ie, a flash of not less than 2 seconds) is used, the period of the light is 10 seconds,
Retroreflectors
One or more white bands, letters, numerals, or symbols of retroreflective material are used for unlighted Safe Water marks in the Standard Code.
Red and white stripes or bands are used in the Comprehensive Code.
SPECIAL MARKS
To indicate to the mariner a special area or feature, the nature of which is apparent from reference to a chart, Sailing Directions or Notices to Mariners, Special marks may be used. Special marks may be lettered to indicate their purpose.
Uses include the marking of: ODAS buoys;
Traffic Separation Schemes where use of conventional channel marking might cause confusion, though many schemes are marked by Lateral and Safe Water marks;
Spoil grounds;
Military exercise zones;
Cables or pipelines (including outfall pipes);
Recreation zones.
Another function of Special marks is to define a channel within a channel. For example a channel for deep-draught vessels in a wide estuary, where the limits of the channel for normal navigation are marked by red and green Lateral buoys, may have the boundaries of the deep channel indicated by yellow buoys of the appropriate Lateral shapes, or its centreline marked by yellow spherical buoys.
Colour
Yellow is the colour for Special marks.
Shape
Optional shapes are used for Special buoys, but must not conflict with that used for a Lateral or Safe Water mark.For example, an outfall buoy on the port side of a channel could be can-shaped but not conical.
Topmark
A single yellow X is the form of topmark used, when one is carried.
Lights
A yellow light is used, when one is exhibited. The rhythm may be any, other than those used for the white light of Cardinal, Isolated Danger and Safe Water marks. The following are permitted examples:
Group occulting;
Flashing;
Group flashing with a group of 4, 5 or (exceptionally) 6 flashes;
Composite group flashing Morse code letters, other than Morse code (A), (D) or (U)
In the case of ODAS buoys, the rhythm is group flashing with a group of 5 flashes every 20 seconds.
Retroreflectors
One yellow band, or an X, or a symbol are used as retroreflectors for unlighted Special marks.
***If these shapes are used they will indicate the side on which the buoys should be passed
So, this is the end of the series of articles related to the IALA Maritime Buoyage System. Stay tuned to our blog until we meet you in a series of important articles like this. Leave your comments below..good day..!!!
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