156 HYDROGRAPHIC MANUAL PaGE 42 



156. Statistical and Cost Data 



Each Chief of Party is required by the Regulations to submit certain statistical 

 and cost data relative to his field work. Among the forms required for this purpose 

 are: Form 20a, Monthly Report and Journal of Field Party; Form 21, Statistics, Cost, 

 and Summary of Field Work, and Form 615, Summary of Monthly Reports and Jour- 

 nals of Field Party and Cost Apportionment, the two latter required at the end of 

 each season; and Form M-1 133-5, Annual Statistical Report, which is submitted at the 

 end of the fiscal year. (See also 851.) 



For use in preparing the required seasonal and annual reports Form 20a should be 

 complete and accurate; the cost data should correspond with those on Form 474, State- 

 ments of Allotment Balances, and the sums to date of the entries for each fiscal year 

 should agree with the total encumbrances or total payments appearing on the State- 

 ments of Allotment Balances for the various appropriations. 



As a convenience in the preparation of these and other forms, each Chief of Party 

 should have memoranda kept of the various items involved as the work progi'esses, as 

 this will save extensive examination of the records and will avoid a reliance on memory 

 at the end of the season. Planning of the field operations with the preparation of 

 these reports in mind will aid in their compilation. 



A commendable practice is the inclusion in the season's report of a chronology of 

 the important events occurring during the season. Memoranda kept of these as they 

 occur will greatly facilitate the preparation of this report. 



157. Current Surveys 



A knowledge of tidal and other currents is of great importance to the mariner, and 

 current observations are required upon which to base published current predictions. 

 Systematic current surveys are usually made by survey parties especially organized 

 and instructed for this work, and long series of current observations are made from time 

 to time by the personnel of lightships through the cooperation of the United States 

 Coast Guard. 



In areas where currents of importance to navigation occur and detailed current 

 surveys have not been made, current observations should be obtained by the hydro- 

 graphic party. Especially valuable are current data obtained in calm weather from 

 survey vessels at offshore anchorages. The current should be measured with current 

 pole and line in accordance with the procedure outlined in Special Publication No. 215, 

 Manual of Current Observations. To be of material value the observations should 

 cover a period of not less than 25 consecutive hours, although shorter series, such as 

 overnight observations, will have some value when the longer series cannot be secured. 



158. Navigation and Seamanship 



A knowledge of and experience in the technique of surveying is of little practical 

 value in hydrographic surveying unless supplemented by a proficiency in navigation 

 and seamanship; in fact, skill in many phases of hydrographic surveying can scarcely 

 be attained, or is almost useless, without an accompanying ability in navigation and 

 seamanship. The operation of sounding from a vessel underway frequently requires 

 navigation of the highest order, and many of the conditions which are encountered 

 almost daily by the hydrographer are met by the average mariner only in emergencies. 

 A knowledge of how to navigate and handle his vessel under all conditions and of the 



