916 HYDROGRAPHIC MANUAL PaGE 828 



CENTER HEADS. — These are to be typed or lettered in capitals, and in place in the manu- 

 script. The chart number is given on the second line immediately below, in parentheses and centered. 



CHANGE OF SHORELINE OR DEPTHS.— Mention any reliable evidence as to recession 

 or extension of shoreline or change of depths. Note important facts regarding changes observed. 

 Give evidence, if any, of subsidence or emergence of shores. Locate and describe the limits of a 

 dumping ground for dredged or other materials. Report all obstructions. Temporary obstructive 

 operations, such as dredging or other rapidly changing conditions, should not be described. Ob- 

 structions that will remain for several years, such as those incidental to the construction of a large 

 bridge, should be described. Note especially localities where changes of any sort affecting navi- 

 gation are likely to occur, and report to the Office those which should receive frequent attention so 

 that publications may be kept up to date. 



CHANNELS. — In the Pilot give controlling depths of channels, widths if necessary, and the 

 probability of change. Where dredging is mentioned, state if the channel depth is maintained by 

 maintenance dredging. If the controlling depth given is not for the entire width of the channel as 

 shown by the channel lines on the chart, give as much information as is warranted. In some cases 

 the project should be described, and the extent of completion should be given, with the date. Give 

 the character of the bottom. State whether the sides are defined, at high or low water, by spoil, 

 color, marine growth, etc., and give light effects if they are of any aid in distinguishing the channel 

 limits. 



The reviser shall call at each District Engineer Office in the region covered by the Pilot being 

 revised and obtain the most recent information available on the condition of the waterways under the 

 jurisdiction of each office. The peculiarities of some of the dredged channels may be of great value. 

 Tendencies to fill at certain places and the reasons for the filling, such as currents, current eddies, 

 sloughing, floods, seasonal freshets, and ice, are important and should be explained in the Coast 

 Pilot wherever such a condition is known to exist. If the depths are stable and changes affecting 

 navigation are rare, explain. The extent of maintenance dredging is importanc. Where rock out- 

 crops exist in dredged channels, with less water over them than the general dredged depth, it is im- 

 portant to state that the bottom is rock. 



State the maximum draft known to have been taken through the channel. Where the maximum 

 draft diflFers from the minimum depth in the channel, give the reasons, as swell, squat, tide, and rocky 

 or soft bottom. Note the depth and character of approaches to wharves, piers, drydocks, marine 

 railways, and coal stations, and give the manner of approaching them, and why. (For channels 

 over bars, see Bars.) 



Describe aids to navigation as necessary. In some well-marked channels, it will be sufficient in 

 writing Directions to say to follow the aids. Usually it is better to give courses and distances for use 

 in fog. 



For emphasis it may be advantageous to give the least depth and its location in a separate 

 paragraph. 



Local information as to depths may not be dependable. Such information should be most care- 

 fully checked, by soundings, if possible. Refer to the file of chart standards in the Nautical Chart 

 Branch, and then to the survey sheets, or to the blueprints of the U. S. Corps of Engineers, as may be 

 necessary, to obtain information not yet shown on the charts. 



If a special method of showing the depths is used on the chart, such as by quarter widths of the 

 channel, the method used should be described in such detail as is necessary to make it clear. 



If the depths change, or the position of the channel shifts so frequently that details of these changes 

 are given in Notices to Mariners, either at regular or irregular intervals, include that information in 

 the Pilot. 



In describing channels of such width that objects on both sides may be used simultaneously by the 

 navigator, the channel should be described as a whole. Otherwise, the descriptions of diflFerent sides or 

 sections of the channel may be separated in such a manner as to conform best to the layout of the Pilot. 



CHART CHANGES. — Before sending the manuscript of either a new edition or a Supplement to 

 press, the Nautical Chart Branch must be consulted for changes in the limits of the charts or in chart 

 numbers for the region being covered. 



CHECKING. — The importance of checking the manuscript cannot be overemphasized. Unless 

 this is done thoroughly, errors are certain to occur. 



Every line of the manuscript, not only the parts that are changed, must be read and checked 

 with the charts. The field reviser should use a system of checkmarks to indicate what he has checked 

 in the field. 



