145 CHAPTER 8 BUOYAGE 8.1 GENERAL The term `buoyage encompasses all floating structure such as buoys or beacons which are used to orientate mariners and to mark the edges of navigable channels and fairways. Structures in this group are also used to mark hazards to navigation such as, shoals, banks, rocks, wrecks, and danger zones. (Lightvessels, as far as they still exist, form a separate category by themselves.) They generally serve as guides during daylight. When fitted with a light, they are also available for navigation at night. Those having a sound signal also indicate their position in fog or other conditions of low visibility. Buoys and beacons are also referred to as `buoyage marks or simply `marks, and are distinguished from one another by their shape, colour, topmark, number, characteristics of light and/or sound signal. In coastal waters and harbours buoyage is also used for the following special purposes: a. Indicating limits of fishing grounds where submerged nets may be encountered: fish trap buoys. b. Indicating moorings for vessels: barrel buoys, tun buoys, or mooring buoys. c. Carrying oceanographic or meteorological sensors: ODAS (Ocean Data- Acquisition System) buoys. d. Indicating telegraph or telephone-cables or pipelines: telegraph-cable buoys. e. Indicating the limits of anchorage areas: anchorage buoys. f. Indicating quarantine areas: quarantine buoys. g. Verifying the position of light-vessels: watch buoys or station buoys. 8.2 CONSTRUCTION OF BUOYS There are many different kinds of buoys. Most buoys are painted a conspicuous colour and consist of the following components (Figure 8.1): a. a body or float with anchoring or mooring device; b. a superstructure (cage-work or pillar); c. a lantern; d. a topmark (various shapes); e. a radar reflector; f. a sound device (bell, gong, whistle, or horn); g. a conspicuous colour.
Buoys equipped with a light are called lighted buoys. When they have no light they are called unlighted buoys or ordinary buoys. Buoys having a sound device only are called sound buoys. Buoys may be classified by their shape as follows: Beacons. Spar buoys. Ordinary buoys. General purpose buoys also called standard buoys. Short pillar buoys. High pillar buoys, also called high focal plane buoys. Beacons, spar buoys and ordinary buoys have no superstructure and are usually unlighted; general purpose and pillar buoys have a superstructure and are usually lighted. General purpose buoys and pillar buoys are usually also equipped with a sound device. 146 Depending on the power used for the lantern, we distinguish propane, acetylene, or electric buoys. (Propane and acetylene are rarely used nowadays.) Buoys bearing lights and sound devices are usually called combination buoys. According to their sound device they may also be called `light and bell buoys, `light and whistle buoys, etc. Figure 8.1 General Purpose Buoy a. Mooring; b:body; c: superstructure (can-shaped) d: lantern; e: topmark; f: radar reflector; g: fog signal (bell) 8.2.1 Body of the buoys The body of the buoy is a steel float, varying in size and shape, according to the type of buoy. It is composed of an immersed part and of an emerged part. The submerged part gives the necessary buoyancy. The part above water gives the buoy its particular shape or serves to support its superstructure, lantern, topmark and other devices. The body is always hollow and is used to store gas or batteries for the lantern. Ordinary buoys can be identified both by the shape of their body and their col-
our. Lighted buoys, on the other hand, can be identified by their superstructure or topmark. 8.2.2 Mooring 147 The buoy is anchored to the bottom by a chain and a heavy block of concrete, called sinker (Figures 8.2 f and 8.3 f). When the bottom of a buoy is fitted with two diametrically opposed mooring eyes, the chain is fastened to the buoy by a six metre long `bridle (Figure 8.2 a). When the buoy has only one central mooring eye, an 8 metre long single pendant mooring chain called tail chain (Figure 8.3 a) is used. Figure 8.2 - Mooring with bridle a: bridle; b: triangular link; c: swivel; d: riding chain; e: ground chain; f: sinker. Figure 8.3 - Mooring with single pendant chain a: tail chain; b: triangular link. c: swivel; d: riding chain; e: ground chain; f: sinker. A mooring chain is composed of links, typically made from 35 mm gauge steel. The length of chain is about three times the water depth, depending on the weight of the buoy, depth of water, speed of current, and range of tide. The chain is fitted with a swivel every 20 metres to prevent entanglement (Figures 8.2 c and 8.3 c). Two thirds of the chain rests on the bottom and is called `ground chain (Figures 8.2 e and 8.3 e). The other third which hangs between the buoy and the bottom of the sea is called `riding chain (Figures 8.2 d and 8.3 d). The buoy is thus able to rise and fall with the waves and there is no risk that the sinker will be lifted and moved from its position.
148 Figure 8.4 - Sinker The sinker is a heavy block of cast iron or concrete. The bottom of the sinker is concave to enable it to be held firmly to the sea-bed by suction (Figure 8.3 f). Concrete sinkers are composed of concrete and scrap iron. The scrap iron serves only to bind the concrete together (Figure 8.4). The weight of a sinker may vary between 1,000 and 5,500 kg., depending upon the weight of the buoy, the sea conditions and the nature of the sea-bed. The anchorage of the sinker is reinforced by a mushroom anchor on sloping or rocky bottoms and on sites where strong currents are running (Figures 8.5 and 8.6). Figure 8.5 Mooring with a mushroom anchor Figure 8.6 Mushroom anchor 8.2.3 Superstructure Every buoy should have a well-defined shape. The three main shapes are : conical (Figures 8.7 and 8.8) can (Figures 8.9 and 8.10) spherical (Figure 8.11). NOTES 1. Buoys shown in Figures 8.8, 8.10 and 8.18, are only encountered in American waters. 2. In the U.S., conical buoys are called nun buoys.
149 Other shapes in use are : a. spar (Figure 8.12); b. with superstructure (Figures 8.13 to 8.18 inclusive)1. Figure 8.7 Figure 8.8 Figure 8.9 Figure 8.10 Figure 8.11 Figure 8.12 Figure 8.13 Figure 8.14 Figure 8.16 Figure 8.15 Figure 8.17 Figure 8.18 Conical buoys have the shape of a cone with the pointed end uppermost, and can buoys have the shape of a cylinder. Spar buoys have the shape of a thin vertical pole. ADDITIONAL ILLUSTRATIONS Trinity Harwich Buoy Yard
150 Ostend Buoy Yard Ostend Buoy Yard Finland Buoy Types
151 Australia ZENI Jets Sinkers at the Ostend Buoy Yard
152 8.3 ORDINARY BUOYS 8.3.1 Beacons These may be divided into : a. floating beacons; b. fixed beacons; c. stakes; d. tower beacons. Floating beacons have the same appearance as spar buoys and consist of a barely visible float surmounted by a thin, vertical wooden pole (Figures 8.19, 8.20 and 8.21). Fixed beacons are wooden poles which are driven into the sea bottom (Figure 8.22). Stakes are branches which are planted along the edges of a channel. The branches may be loose (Figure 8.23) or tied together like brooms (Figure 8.24). Towers are fixed constructions on the water (Figure 6.5). Figure 8.19 Floating beacon with can Figure 8.20 Floating beacon with can topmark Figure 8.21 floating beacon with radar reflector
153 Figure 8.22 Fixed beacon with can topmark Figure 8.23 Stake with loose branches Figure 8.24 Stake with tied branches Floating and fixed beacons are usually painted and rarely carry a number or name. They mostly have a topmark giving to the beacon the shape of the buoy which they replace. Sometimes they are fitted with a radar reflector. Floating beacons are mostly used during the winter as temporary replacements for ordinary buoys, or to mark secondary or shallow channels or fairways. They are mainly encountered in channels and inland waters. Indication of beacons on charts With a few exceptions all beacons are charted in the same way. See symbols and abbreviations used on marine charts, (Plate Q). Fixed beacons are frequently encountered in American waters where they are mostly used as daymarkers. They are shown on charts by a small square or a small triangle pointing upwards, or by a small circle with dot with or without the abbreviation Bn and with the abbreviation of the colour of the beacon. (Figure 2.49). Besides ordinary beacons, mariners may also encounter the following : a. compass adjustment beacons; b. telegraph-cable (landing) beacons; c. cairns; d. painted patches; e. oil installation buoys; f. offshore or drilling platforms.
154 8.3.2 Spar buoys Spar buoys are floating objects of cylindrical shape, having a relatively small diameter compared with their height. They are rarely fitted with a light. One or two topmarks may be used to give the beacon a well-defined meaning with respect to the shape that it should normally have. In Holland, a distinction is made between `conical spar buoys and can spar buoys. In the USA, the Coast Guard no longer uses spar buoys. They are usually replaced by daymarkers. 8.3.3 Ordinary buoys Ordinary buoys are normally unlighted. The characteristics of these buoys are generally determined by their above-water shape and by their colour. They may be fitted with a topmark or radar reflector. They are mostly fitted with a topmark when sited as follows : a. as first mark in a channel; b. in a bend; c. as a cardinal mark. The main shapes are : conical (Figure 8.25), can (Figure 8.26), and spherical (Figure 8.27). The height of ordinary buoys may vary between 1.5 and 5 metres. Usually one quarter of the body is submerged and three quarters is above water. The diameter usually varies between 1 and 4 metres. Figure 8.25 Conical buoy Figure 8.26 Can buoy Figure 8.27 Spherical buoy Figures 8.28 and 8.29 show small buoys being used as ordinary marks in European waters.
155 Figure 8.28 Figure 8.29 Figure 8.30 - Nun buoy (Photo : U.S. Coast Guard) Figure 8.31 - Can buoy (Photo: U.S. Coast Guard)
Figures 8.30 and 8.31 show typical small ordinary buoys, as encountered in American waters. The buoy shown in Figure 8.30 is called a `nun buoy and the one shown in Figure 8.31 is called a `can buoy. 156
157 8.4 LIGHTED BUOYS The bodies (or floats) of lighted buoys may, in principle, be either can shaped (Figure 8.32) or cone shaped (Figure 8.33). The above-water part may vary in shape depending on the type of buoy : general purpose buoy, short pillar buoy or high pillar buoy. 8.4.1 General purpose buoys General purpose buoys have a cage-work structure built to their body. They have a volume of about 10 m 3 and weigh approximately 5,000 kg. The lights of general purpose buoys are generally powered by solar panels. Before they were powered by acetylene or propane gas. In some countries this may still be the case. The significance of a particular buoy is conveyed by its superstructure and/or topmark and by its colour. The superstructure may be conical (Figure 8.34), cylindrical (can) (Figure 8.35), or spherical (Figure 8.36). The superstructure carries the name or number of the buoy. The lower part of a general purpose buoy is usually cylindrical and draws about 1 metre of water. The buoy is attached to its mooring chain by means of a bridle. The focal height is about 3.5 metres. Figure 8.1 shows a typical general purpose light and bell buoy. Figure 8.32 - Can shaped body Figure 8.33 - Cone shaped body
158 Figure 8.34 Conical superstructure Figure 8.35 Can superstructure Figure 8.36 Spherical superstructure NOTES 1. There are no general purpose buoys in the American buoyage system. 2. Some general purpose buoys have no lanterns. These should be considered as ordinary buoys, in which case they usually have a sound device and are then classified as sound buoys. Figure 8.37 shows a general purpose buoy with a conical superstructure, a lantern, and a radar reflector. Figures 8.38 and 8.40 show general purpose buoys with a can superstructure and a radar reflector. Figure 8.39 shows a general purpose buoy with a can superstructure and a topmark. Figure 8.41 shows a general purpose buoy with a spherical superstructure, a lantern, a radar reflector, and no topmark.
159 Figure 8.37 - Conical buoy Figure 8.38 - Can buoy Figure 8.39 - Can buoy Figure 8.40 - Can buoy
160 Figure 8.41 - Spherical buoy NOTE The buoys shown in Figures 8.37, 8.38, 8.39, 8.40, and 8.41 are buoys used in European waters.
161 8.4.2 Pillar buoys The superstructure of these buoys is of metal and they have the shape of a frame-work, trellis, or tower. A distinction should be made between the pillar buoys used in European waters and those used in American waters. Pilar buoys are also called tower or tall buoys. 8.4.3 Pillar buoys used in European waters A distinction should be made between high pillar buoys and short pillar buoys. High pillar buoys (or high focal plane buoys) are distinguished from short pillar buoys by the height of their superstructure. Short pillar buoys have a volume of 10 m 3 a weight of 7,000 kg. and a focal height of 4 metres (Figure 8.42 and 8.44). High pillar buoys have a volume of 20 m 3 a weight of 14,000 kg. and a focal height of 8.5 metres (Figure 8.43 and 8.45). Figure 8.42 - Short pillar buoy European waters Figure 8.43 - High pillar buoy American waters
162 Figure 8.44 - Short pillar buoy European waters Figure 8.45 - High pillar buoy European waters Pillar buoys can be identified by their colour and their topmark. In fact, pillar buoys nearly always carry a topmark. They are mostly lighted buoys and the lantern is nowadays powered by solar panels. A circular panel placed just below the lantern or the solar panel(s) carries the number and/or the name of the buoy. The under-water part of the body shown in Figures 8.46 and 8.47 is elongated and cylindrical. Its length is in proportion to the height of the pillar in order to give the buoy sufficient buoyancy and stability. It is fitted with a rudder (Figure 8.47 h) to hold the buoy steady particularly at the turn of the tide. The central part of the body is hollow and partly filled with water up to the water line. The air above the water line is used for operating the whistle. A hanging chain in the tail called `anti fouling chain (Figure 8.46 j) prevents any seaweed from settling on the inner side of the tail.
163 BEFORE Figure 8.46 - High pillar buoy a: pillar tower; b: circular panel; c: lantern; d: radar reflector; e: whistle; f: bell; g: body; h: acetylene cylinders; i: tail; j: anti fouling chain NOW Figure 8.47 - High pillar buoy a: pillar tower; b: solar panel; c: lantern; d: topmark; e: radar reflector; f: body; g: tail; h: rudder; i: mooring eye for anchor chain
164 Indication of buoys on charts The shapes of buoys, their symbols and abbreviations, are shown in a uniform way on all European charts. Both lighted and unlighted buoys are represented as accurately as possible on charts by a small design depicting the shape of the buoy and topmark. The exact position of the buoy is the centre of the base and is indicated by a small circle. Lighted buoys are shown by a magenta tear drop or light-flare. (See also 8.4.3.1 The lantern.) Symbols representing buoys on charts normally slope to the right, if space permits, otherwise to the left. The standard buoy symbols in use are: a. conical shape: a solid black symbol: b. can shape: an open symbol: c. spherical shape: an open symbol d. pillar buoy: an open symbol or a solid black symbol if it represents a conical buoy (e.g. a starboard hand mark); e. spar buoy: a solid black symbol; f. ordinary beacon: a solid black and upright symbol; NOTE The symbols with diamond shapes and square are used on American charts.
g. tower beacon: a solid black symbol when representing a starboard hand mark; otherwise an open symbol; 165 h. floating beacon: a solid black symbol when representing a starboard hand mark; otherwise an open symbol; i. topmarks: solid black symbols, except for a solid red sphere representing a Safe Water mark and a red can indicating a port Lateral mark. REMARKS 1. The above-mentioned symbols are those used in the IALA-System A and B, by the IHO (International Hydrographic Organization) the NOS (National Ocean Service - US) and the NIMA (National Imagery and Mapping Agency - US). For more symbols, see Chart 5011 Symbols and Abbreviations used on Admiralty Charts and particularly Plates L, P, Q, R and S. 2. See also symbols and abbreviations used on marine charts and published by other Administrations. 3. As you may have noticed, buoys on American charts are shown in an entirely different way. 4. For symbols and abbreviations of buoys on European charts, refer to Figures 2.44, 2.46, 2.47, 3.4, 3.6b, 3.15, 3.21, 6.3, and 8.63. 5. For symbols and abbreviations of buoys on American charts, refer to Figure 2.48 to 2.52.