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of unusual length, or those involving a number of charts (as where Directions for a port are given 

 from several points), may be center-headed. (See explanation of Plymouth Harbor Directions in 

 9135B(4).) 



Directions must be scaled with special accuracy and care. They must be plotted on the largest- 

 scale charts, and the routes must be examined carefully to make certain that the recommended courses 

 are safe and the best. In selecting routes, the writer must bear in mind that, although many vessels 

 use certain cutoffs or special routes that may save them a little time, the Coast Pilot should recom- 

 mend only routes that are safe and conservative. An able navigator, with local knowledge, can use 

 many short cuts, but these should not be recommended to the general public. (See Two-way courses.) 



All positions in Directions should be referenced to fixed objects of a permanent nature. In some 

 cases it is necessary to refer to buoys, but avoid, as far as possible, the use of objects of a changeable 

 nature or those whose positions are subject to change. Many changes in Supplements can thus 

 be avoided. 



Directions should not be given for channels that are so shifting in character as to make the 

 Directions unreliable. In some cases they may simply consist of instructions to follow the aids as 

 found, with a statement that the aids are moved as the channel shifts its position. Any known 

 tendencies to sloughing, filling, or shifting of dredged channels should be described. 



Tabulated Directions shall be given in the form illustrated in 9135B(3). 



(See Checking, and Port and starboard.) 



DISCOLORATION OF WATER.— This should be described in detail where it may occur to 

 such an extent as to affect navigation. 



DISTANCES. — Distances should be given in nautical miles and tenths, or in yards where 

 greater accuracy is required. In the Intracoastal Waterway Pilot, follow the system of the U. S. 

 Corps of Engineers, which is statute miles. Do not use fractions; the graphic scales on the charts 

 are in decimals. The lengths of short courses in Directions may be given to the nearest 0.05 mile. 

 In giving lengths of measured trial courses, use as many decimals as are necessary for accuracy. 



DOCKS. — A dock is the slip or waterway between two piers or projecting wharves. (See 

 Wharves.) 



DOCK CHARGES. — State if they are made, but do not give the rates. 



DOLPHINS, PILES, ETC. — If of importance to navigation, mention their approximate locations 

 and use; whether for tying up to, for storage, for working off wharf, etc. 



DRYDOCKS.— (See Marine railways.) 



DUES— PORT, DOCKAGE, PILOT, ETC.— These are generally too changeable to permit 

 their quotation. In some cases, where fixed by law, it is permissible to quote in part if considered 

 desirable. 



ECHOES.— (See Sound reflection.) 



E. D. — (See P. D. and E. D. dangers and soundings.) 



ELEVATIONS. — Refer elevations to the same datum used on the charts, e. g., mean high water 

 (see Datums). Give known or estimated elevations in all cases where the information may be of 

 value to the navigator. This is of particular importance where the elevation will help identify a 

 landmark, an offshore rock, etc. 



FACILITIES. — Facilities for handling cargo should be briefly noted. The purpose is to inform 

 ship officers if they must be prepared to use their own cargo gear. Give the rate at which coal and 

 oil are loaded, and whether fuel and water may be taken at the wharves. (See Bunkering.) List tlie 

 general facilities available, such as electric power, stevedores, rail connections, etc. 



FERRIES. — The reviser may find it advisable to take trips on some ferries to note the routes 

 followed and to obtain information from their captains. It is desirable to note in the Directions 

 the localities where ferries usually cross main steamship tracks. This information may be of con- 

 siderable value during fog. 



Information should be given as to the kind of ferry, whether passenger, freight, or automobile, 

 and ports at which ferry service is available. This is of particular importance in comparatively 

 isolated regions. 



FIELD WORK. — The reviser in charge of the field inspection shall ascertain whether the various 

 divisions of the Bureau desire him to do any special field work, and also shall report to the Bureau 

 on needs for surveys. Reports by individuals and organizations that field surveys are needed should 

 be supported by evidence of the need. The reviser should recommend further surveys on account of 

 developments, shoaling, changes, wrecks, reports of obstructions, inadequacy of old surveys, etc. 



