7734 HYDROGRAPHIC MANUAL PaGE 724 



7734. Fractions and Decimals 



Figures in a fraction or the decimal parts of a depth unit must be smaller than whole 

 numbers. In general, the over-all height of a fraction should not be more than 15 

 percent greater than the over-all height of the whole numbers in that vicinity. Where a 

 fraction stands alone the horizontal bar between the numerator and denominator 

 must be included, in order to avoid mistaking the component parts of the fraction 

 for whole numbers. But if the sounding is a mixed number — that is, where a fraction 

 accompanies a whole number — the bar shall be omitted. 



The decimal part of a fathom shall be considered as the numerator of a fraction 

 whose denominator is 10, but with the denominator omitted, and shall be so penciled 

 and subsequently inked on the smooth sheet. The horizontal bar which is normally 

 used between the numerator and denominator of a fraction shall be retained as a 

 line under the decimal part of the sounding. 



No depth shall ever be shown as a decimal alone. Wliere the depths are less than 1 

 fathom, on a smooth sheet whose depth unit is fathoms, the decimal part shall be 

 preceded. by zero, as 0-. 



Greater care must be taken in penciling and inking fractions and decimals than 

 is necessary with whole numbers, since their smaller size requires greater perfection in 

 the formation of the numerals, in order that they shall be perfectly legible in spite of 

 their reduced size. 



In congested areas it is particularly important that fractional numbers be so 

 drawn and so spaced that no doubt can ever arise as to whether a fraction stands 

 alone or is part of an adjoining number. 



7735. Zero and Minus Soundings 



Where zero soundings are placed on the smooth sheet, extreme care must be taken 

 in drawing these figures in order that they will not be mistaken for off-lying rocks or 

 islets. This i§ especially important along rocky coasts where small isolated bare 

 rocks or islets are frequent. 



A minus sounding (see 7715) should be preceded by a minus sign (e.g. —2). If the 

 minus sounding is a fraction, the minus sign shall precede the numerator, and not be on 

 a line with the bar between the numerator and denominator, since in the latter case 

 it might be mistaken for a part of the bar. (See also 7734.) 



7736. Position of Numerals 



The center of the number, including the fraction if any, is considered the position 

 of that sounding and shall be so penciled and inked on the smooth sheet, except for 

 the soundings at positions. 



In penciling or inking soundings at positions it is important not to obscure the 

 position dot by any part of the number. Therefore, in those cases, where the 

 number is composed of an even number of digits, considering the fraction, if any, as 

 one digit, the sounding shall be placed with an equal number of digits on each side of 

 the position dot. Where the number is composed of an odd number of digits it shall 

 be placed as follows: (a) one-digit numbers immediately to the right of the position 

 dot; and (b) three-digit numbers with the first digit to the left, and the second and third 

 digits to the right of the position dot. 



