A Treatise On The Principles And Practice Of Harbour Engineering

CHANNEL DEMARCATION. 255 “ 14. Buoys intended for MooringS, etc., may be of shape or colour according to the discrétion of the authority within whose jurisdiction they are laid; but for marking submarine telegraph cables, the colour shall be green, with the word ‘ Telegraph ’ paiuted thereon in white letters. “ 15. Wreck buoys in the open sea, or in the approaches to a harbour or estuary, shall be coloured green, witli the word ‘Wreck painted in white letters on them. “ 16. When possible, the buoy shall bc laid near to the side of the wreck next to mid-channel. “ 17. When a wreck-marking vessel is used, it shall, if possible, have its top sides coloured green, with the word ‘Wreck’ in white letters thereon, and shall exhibit :— “ By day : Three balls on a yard 20 feet above the sea, two placed vertically at one end and one at the other, the single ball being on the side nearest to the wreck. “ By night: Three white fixed lights similarly arranged, but not the ordinary riding light. “ 18. In narrow waters or in rivers, harbours, etc., under the jurisdiction of local authorities, the same rules may be adopted, or, at discretion, varied as follows :— “When a wreck-marking vessel is used, she shall carry a crossyard on a mast with two balls by day placed horizontally, not less than 6 nor more than 12 feet apart, and two lights by night similarly placed. When a barge or open boat only is used, a flag or ball may be shown in the daytime. “ 19. The position in which the marking vessel is placed with refer- ence to the wreck shall be at the discretion of the local authority having jurisdiction.” Design of Buoys.—The design of a buoy should obviously be such that it will always float upright and be subject to the least possible dis- turbance of equilibrium in boisterous weather and from drifting ice. Long, narrow buoys, constructed on the principle of the angler’s float, are best adapted to withstand currents and rough seas, provided they be not moored from the nether apex, in which case, unless heavily weighted, they tend to heel over considerably. The mooring is preferably attached by a saddle or bridle arrangement at a considerably higher level. Elongated buoys are specially characteristic of German practice, on account of the great quantities of floating ice which obstruct the Baltic Sea and its influents during the winter season. Broad-based buoys are suitable for smooth, shallow waters: they take the ground satisfactorily in the event of exceptionally receding tides. In sheltered positions, flat bottoms with rounded bilges make a good arrangement; in a heavy seaway the rounded bottom is to be preferred, or the hollow cone, as m Admiral Herbert’s design. Size of Buoys.—Buoys are classified as first- or second-class, according to their size. The following table shows the generally accepted dimensions of