52 



NAUTICAL CHART MANUAL 



TIDE NOTE 



Upon request by the Nautical Chart Division, tidal information is furnished on Fonn 

 C&GS-832, "Tidal Information" from the Tides and Currents Branch, Marine Data Division. 



Values given in the tide note of a chart are referred to the plane of reference of the sound- 

 ings on that chart. Thus, the amount stated under Mean High Water is the mean of all high 

 waters observed at the station named. The amount stated under Extreme Low Water is 

 actually the lowest tide observed during the period in which tidal observations were made. 

 This period may be a few days or many years. The date of the tide note is that on which 

 the latest information was appUed. This note should be checked for new values approximately 

 every three years. The date checked shall be given in the lower left corner, thus: 



(363) =month and last two digits of the year. 



Where applicable, the standard form of tide note shown below shall be used on all charts 

 of scale larger than 1 : 200.000. 



TIDAL INFORMATION 



(363) 



The approximate geographic position should be shown at each tidal place not easily located 

 on the chart. 



DEPTH UNIT 



All soundings on any one chart must be expressed in the same depth unit, either feet, 

 fathoms, or the combined form fathoms and feet (to 11 fathoms). This applies to large-scale 

 plans on a chart and also to all of a group of plans forming a chart. However, channel legends 

 and controlling depth tabulations may be expressed in feet on a chart showing soundings 

 in fathoms. 



SIZE OF FIGURES FOR SOUNDINGS (Fig. 21) 



Unless figures of uniform size are used on a Compilation or Drawing, a proper selection of 

 soundings cannot be made. Large figures usually result in a selection of soundings that are 

 too widely spaced. The figures used should not be larger than 2 mm., nor smaller than 1.5 mm. 



FRACTIONS 



Fractions without a whole number should have a bar between the numerator and the de- 

 nominator, e.g., i. In fractions accompanying a whole number, the bar is omitted, e.g., H. 



