Chapter - 06

Buoys And Lighthouses

Lighthouses, Their Significance To The Mariner

Lighthouses are the signal stations by means of which mariners determine their exact position. Mariners had once to be satisfied with natural landmarks, from which to obtain their bearings. These often being lacking at points where most needed, towers were built, and eventually lights were placed in many of them. The modern lighthouse represents the scientific development of this same idea, the signalling equipment being the culmination of many years of striving to overcome the limitations of visibility and audibility.

Coloring Of Structures

Color is applied to lighthouses and automatic light structures for the purpose of making them readily distinguishable from the background against which they are seen, and to distinguish one structure from others in the same general vicinity. Solid colors, bands of color, and various patterns are applied solely for these purposes. Minor light structures are sometimes painted black or red, to indicate the sides of the channel which they mark, following the same system used in the coloring of buoys. When so painted, red structures mark the right side of the channel, and black structures the left side of the channel, entering from seaward.

Light Colors And Characteristics

The colors of the lights shown from lighthouses, and their characteristics or manner in which they flash, are for the purpose of distinguishing one light from others in the general vicinity and avoiding confusion with lights used for other purposes. The length of the flashes and the intervals between may be accurately timed, and positive identification made by consulting the Light Lists. The colors of minor lights, when red or green, may also have the further significance of indicating the side of the channel which the light marks, red being on the right, and green on the left side entering from seaward.

Fog Signal Characteristics

Fog signals, both at lighthouses and on lightships, sound distinctive blasts. This is for the purpose of distinguishing one station from another. The characteristic of every fog signal is given in the Light Lists, and many of them are also given on the charts. All signals sound on a definite schedule, and positive identification may be made, even when the sending station is not visible, by timing the length of the blasts and the intervals between. With practice, mariners may also differentiate between the signals produced by the different types of apparatus.

Beacons

There are many aids to navigation which are not lighted. Structures (not buoys) of this type are called beacons. They vary greatly in design and construction, depending upon their location, and the distance to which they must be seen. A beacon may consist of a single pile with a daymark at the top, a spar with a cask at the top, a slatted tower, or a structure of masonry. Beacons are colored, as are lighthouses, to distinguish them from their surroundings and to provide a means of identification. Beacons marking the sides of channels are colored and numbered in the same manner as buoys and minor light structures; red indicating the right side entering, and black the left side entering.

Lightships

Lightships serve the same essential purpose as lighthouses. They take the form of ships only because they are to occupy stations at which it would be impracticable to build lighthouses. Hulls of all lightships in United States waters, excepting Ambrose Lightship, are now painted red with the name of the station in white on both sides. The superstructures are white, with the masts, lantern galleries, ventilators and stacks in buff. All the signals, the masthead light, the fog signal, and the radiobeacon have distinctive characteristics, so that the lightship may readily be identified under all conditions. A riding-light on the forestay indicates the direction that the ship is heading, and as lightships ride to a single anchor, this also indicates the direction of the current.

Present day lightships are built of steel, with either steam or Diesel engine propulsion. Power for the operation of the signals is obtained from suitable auxiliary machinery. Each lightship has a crew of from 6 to 15 men.

Visibility And Candlepower Of Lights

Under normal atmospheric conditions the visibility of a light depends upon its height and intensity; the distance due to the former being known as the geographic range, and to the latter as the luminous range. As a rule, for the principal lights the luminous range is greater than the. geographic, and the distance from which the principal lights are visible is limited by the horizon only, and under some conditions of atmospheric refraction, the glare or loom of the light and occasionally the light itself may be visible far beyond the computed geographic range of the light. On the other hand, and unfortunately more frequently the case, these distances may be greatly lessened by unfavorable weather conditions due to fog, rain, snow, haze or smoke. Weak and colored lights are more easily obscured by such conditions. The distances of visibility are given in nautical miles.

The intensity of lights is indicated in the Light Lists in terms of candlepower. The chief purpose of these figures is to indicate the relative brilliance of various lights, so that the mariner may judge if a light may be expected to be seen at a great distance or only when approached fairly close to.

Light Characteristics

To avoid confusion, lights are given distinct characteristics, the following being employed:

Fixed: A continuous steady light.

Flashing: Showing single flashes recurring not faster than thirty per minute, the flashes being shorter than the eclipses.

Fixed and flashing: A fixed light varied at regular intervals by one or more flashes of greater brilliance.

Group flashing: Showing at regular intervals groups of flashes.

Quick flashing: Showing not less than 60 short flashes per minute.

Interrupted quick flashing: Showing quick flashes for about four seconds, followed by a dark period of about four seconds.

Short-long flashing: Showing a short flash and then a long flash, this combination recurring about eight times a minute.

Occulting: A steady light totally eclipsed at intervals, the intervals being no longer than the light periods.

Group occulting: A steady light totally eclipsed by a group of two or more eclipses.

Alternating: Lights in which two or more of the colors white, red, and green are used.

The Significance Of Buoys

The primary function of buoys is to warn the mariner of some danger, some obstruction, or change in the contours of the sea bottom, that he may avoid the dangers and continue his course in safe waters. The utmost advantage is obtained from buoys when they are considered as marking definitely identified spots, for if a mariner be properly equipped with charts, and knows his precise location at the moment, he can readily plot a safe course on which to proceed. Such features as size, shape, coloring, numbering, and signalling equipment, are but means to these ends of warning, guiding, and orienting.

Types Of Buoys

The buoyage system as found in waters of the United States consists of several different types of buoys, each kind designed to serve under definite conditions. Broadly speaking, buoys serve as daymarks during the daytime, those having lights are also available for navigation by night, and those having sound signals are more readily located in time of fog as well as by night. The following are the principal general types.

Spar Buoys

Spar buoys are usually large logs, trimmed, shaped, appropriately painted, and moored with a suitable length of chain and a sinker. They vary in length from 20 to 50 feet, depending upon the depth of water in which they are moored. Spar shaped buoys are also constructed of steel plates.

Can And Nun Buoys

Can and nun buoys are built up of steel plates, in various sizes. They are moored with chain affixed to a sinker of appropriate weight.

Bell Buoys

Bell buoys serve with considerable effectiveness both by day and night, and also during fog, and are much used because of their moderate maintenance cost. Most bell buoys are sounded by the motion of the buoy in the sea, four clappers being loosely hung so that they are readily set in motion. Newer types of bell buoys are operated by compressed gas or electric batteries, their strokes sounding at regular intervals, and are particularly useful in sheltered waters.

Gong Buoys

Gong buoys are used to give a distinctive characteristic when there are several bell buoys in one vicinity. In these buoys four gongs of different tones, with one clapper for each gong, take the place of the bell. As the sea rocks the buoy, the clappers strike against the gongs sounding four different notes. There is, of course, no particular sequence to the notes, but the effect is quite distinctive.

Whistle Buoys

Whistle buoys provide a sound signal which is useful at night and also during fog or low visibility. Such buoys also serve as daymarks. They are used principally in open and exposed places where a ground swell normally exists, as the whistle is sounded by compressed air produced by the motion of the buoy in the sea. Whistle buoys have a conical shaped top, above which the whistle projects, protected by cage work. These buoys have no shape significance. In combination buoys, having lights as well as whistles, the whistle is located within the lattice-work tower, immediately below the light. A type of sound buoy is now being introduced in which a trumpet is sounded at regular intervals by mechanical means.

Lighted Buoys

The type of lighted buoy in general use today burns compressed acetylene gas, contained in steel tanks inside the buoy. From the tanks the gas is conveyed by tube to a flasher set in the lantern at the top of the buoy. A valve mechanism operated by the gas pressure permits a definite amount of gas to pass the burner at intervals, to be ignited by a pilot flame which burns continuously. The period and length of the flash may be adjusted to produce a definite characteristic. Flashing lights have a period of light shorter than the period of darkness while occulting lights have a light period equal to or greater than the period of darkness. A few buoys are lighted electrically and the number is increasing.

Combination Buoys

These are lighted buoys which arc also fitted with some form of sound signal, such as a bell, gongs, a whistle, or a trumpet.

The Lateral System

The coloring and numbering of buoys are determined by their position with respect to the navigable channel as such channels are entered and followed from seaward toward the head of navigation. This method, known as the lateral system, is uniform in all United States waters and is described in detail herein under the headings Coloring and Numbering. As all channels do not lead from seaward, arbitrary assumptions must be made in order that the system may be consistently applied. In the coloring and numbering of offshore buoys along the coasts and along traffic routes not leading distinctly from seaward or toward headwaters, the following system has been adopted: Proceeding in a southerly direction along the Atlantic coast, in a northerly and westerly direction along the Gulf coast and in a northerly direction along the Pacific coast, will be considered as proceeding from seaward, and accordingly coastal buoys which are to be kept on the right hand side are red and have even numbers. On the Great Lakes offshore buoys are colored and numbered from the outlet of each lake toward its upper end. The Intracoastal Waterway is marked from the north Atlantic states to the lower coast of Texas, regardless of the compass headings of individual sections.

Coloring Of Buoys

All buoys are painted distinctive colors to indicate their purpose or the side of the channel which they mark.

Red buoys mark the right hand side of channels, entering from seaward.

Black buoys mark the left hand side of channels, entering from seaward.

Red-and-black horizontally banded buoys mark obstructions, or a junction of one channel with another, and indicate that there is a channel on either side. If the topmost band is red, the principal channel will be followed by keeping the buoy on the right hand side of the vessel, when entering from seaward. If the topmost band is black, the principal channel will be followed by keeping the buoy on the left hand side of the vessel, when entering from seaward. (NOTE: When proceeding toward the sea, it may not be possible to pass on either side of these buoys, and the chart should always be consulted.)

Black-and-white vertically striped buoys indicate the middle of a channel, and should be passed close to, but on either side, for safety.

White buoys mark anchorages.

Yellow buoys mark quarantine anchorages.

White buoys with green tops mark areas in which dredging is being carried on.

Black-and-white horizontally banded buoys mark the limits of areas in which fish nets and traps are permitted.

Red or black (unlighted) buoys with white tops have the same significance as similar buoys without the white top, the white painting being added so that the buoys may be readily picked up at night by a ship's searchlight.

Numbering Of Buoys

Most buoys are given numbers, which are painted conspicuously upon them. These numbers serve to indicate which side of the channel the buoys mark, and also facilitate the locating of the buoys upon the charts.

Numbers increase from seaward and are kept in approximate sequence on the two sides of the channel by omitting numbers as required.

Odd numbered buoys mark the left hand sides of channels entering from seaward.
Even numbered buoys mark the right hand sides of channels entering from seaward.

Numbers followed by letters, such as 24A, 24B, 24C, indicate that buoys have been added to a channel and the series not at once renumbered.

Numbers followed by letters, such as 1 DR, are used on important buoys, particularly those marking isolated offshore dangers. The letters are initials of the station name, in this instance Duxbury Reef, and the number has the usual significance.

Letters, without numbers, are applied in some cases to black-and-white vertically striped buoys marking fairways, and to red-and-black horizontally banded buoys marking junctions or bifurcations.

Shapes Of Buoys

Definite shape characteristics have been given to a large portion of the unlighted buoys used in United States waters, to indicate which sides of the channels they mark. Cylindrical buoys with flat tops are known as can buoys, and if painted black, mark the left hand sides of channels entering from seaward. Conical buoys with pointed tops are known as nun buoys, and if painted red, mark the right hand sides of channels entering from seaward. Cylindrical or can buoys, painted in red-and-black horizontal bands, with the topmast band black, are used to indicate an obstruction or a junction of one channel with another, where the principal channel entering from seaward lies to the right of the buoy. Conical or nun buoys painted in red and black horizontal bands, with the topmost band red, have the same meaning except that the principal channel lies to the left of the buoy. (Spar buoys similarly marked have the same meanings.)
Can or nun buoys with black-and-white vertical stripes indicate the middle of a channel, and may be passed safely on either side. In these the shape has no significance.

No special significance is to be attached to the shapes of spar buoys, bell buoys, whistle buoys, gong buoys, lighted buoys, or combination buoys, their purpose being indicated by their coloring, numbering, or the characteristic of the light.

Sizes Of Buoys

The various types of buoys are made in different sizes to fit them for service in waters of different depths and varying degrees of exposure. These sizes in no way affect the significance of the buoys and need not be taken into consideration by mariners except as a means of judging distances.

Color Of Lights

For all buoys having lights, the following system of coloring is used. Green lights are used only on buoys marking the left hand sides of channels entering from seaward. Red lights are used only on buoys marking the right hand sides of channels entering from seaward. White lights may be used on either side of the channel, and such lights are frequently employed in place of colored lights at points where a light of considerable brilliance is required, particularly as leading or turning lights.

Reflectors

Reflectors are placed upon many unlighted buoys, and greatly facilitate the locating of the buoys at night by means of a searchlight. Reflectors may be white, red, or green, and have the same significance as lights of these colors.

Light Characteristics

Fixed lights (lights that do not flash) may be found on either red or black buoys.

Flashing lights (flashing at regular intervals and at the rate of not more than 30 flashes per minute) are placed on either black buoys or on red buoys.

Quick flashing lights (not less than 60 flashes per minute) are placed on black buoys and on red buoys at points where it is desired to indicate that special caution is required, as at sharp turns or sudden constrictions.

Interrupted quick flashing lights (the groups consisting of a series of quick flashes, with dark intervals between groups of about 4 seconds) and placed on buoys painted in red-and-black horizontal bands, indicating obstructions or a junction of one channel with another.

Short-long flashing lights (groups consisting of a short flash and a long flash, the groups recurring at the rate of about 8 times per minute) are placed on buoys painted in black-and-white vertical stripes, indicating a fairway or the middle of a channel where the buoy should be passed close to. The light is always white.

Fish Net Buoys

Particularly, though not exclusively, in the Chesapeake Bay area, buoys are used to mark the limits of areas in which fish nets and traps are permitted, such areas and the buoys being indicated also upon the charts. These buoys are chiefly spars, and are painted in black-and-white horizontal bands.

Intracoastal Waterways Aids

The aids to navigation marking the Intracoastal Waterway have a characteristic yellow marking in addition to their usual coloring to indicate which side of the channel they mark. Buoys have a yellow band at the top. Single pile beacons have a yellow band at the top. Daymarks on light structures have a yellow border.

In addition to the special Intracoastal Waterway coloring, all aids in this waterway are painted in the usual manner to indicate which side of the channel they mark. All aids in this waterway are colored and numbered from north to south along the Atlantic coast and from east to west on the Gulf Coast.

Where the Intracoastal Waterway follows another waterway, the aids in which are colored and numbered in the opposite direction, a yellow triangle is placed on black buoys, and a yellow square on red buoys. This indicates that buoys with the triangular markings are to be considered as nun buoys, and the square marked buoys as can buoys, insofar as a vessel following the Intracoastal Waterway is concerned.

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