6. THE SMOOTH SHEET 



201 



6-4 Sheet margins. — In determining 

 sheet sizes and limits of hydrography it is 

 essential that soundings shall seldom be 

 closer than about 3 inches to the edges of 

 the sheet (see 2-20). By following this pro- 

 cedure the marginally plotted soundings will 

 not become impaired or destroyed later be- 

 cause of repeated handling of the sheet. 



6-5 Sheet extensions. — A limited area 

 extension of a smooth sheet, referred to as a 

 "dog-ear," (Fig. 76) is occasionally neces- 

 sary to include a control station located be- 

 yond the edge of a sheet (see 2-24). This 

 dog-ear appendage, which shall not extend 

 more than 6 inches beyond the edge of the 

 sheet, shall be firmly attached with strips of 

 masking tape applied to the undersides. 

 When the station is plotted on the dog-ear 

 three fine inked lines, annotated with the 

 station name and symbol, shall be drawn at 

 the same time inside the edge of the sheet 



Figure 76. — Temporary extension for smooth sheet. 



at sufficient angles and lengths that, if neces- 

 sary, the station can be relocated after re- 

 moval of the dog-ear. The necessity for use 

 of dog-ears can be minimized by using great 

 care in laying out the sheets (see 1-7 and 

 2-20). 



6-6 Insets and subplans. — Smooth sheet 

 insets and subplans are used to extend the 

 survey coverage shown on one sheet, and to 

 combine contemporary small detached sur- 

 veys on the same project (see 2-23). Small 

 congested areas shall be shown at enlarged 

 scales in subplans in otherwise blank spaces 

 on the smooth sheet where practicable (Fig. 

 77). The scale and extent of the subplan 

 shall be large enough to show the hydrog- 

 raphy clearly and to include the stations 

 used to control the hydrography. 



Enlarged subplans, such as those to in- 

 clude the water area of a small bay, cove, 

 inlet, or anchorage area, shall be surrounded 

 by a heavy margin in black ink. Each sub- 

 plan must include the scale, name of the 

 water area, if any, and at least one meridian 

 and parallel. The area of the subplan should 

 be identified in its true position by a fine 

 dashed pencil outline and an arrow leading 

 to the subplan. Details shown in the enlarge- 

 ment may be omitted from the original scale. 



Where soundings are taken in small docks 

 and along the sides and ends of small piers 

 and are located by reference distances to or 

 along the piers, enlarged plans of these (Fig. 



Scale 1:10.000 



OMAG 



135° 20' 



Ofat 



- 57°0O' 



NITAL COVE 



135°20' S"lg l-^'SOO 



.Figure 77. — Subplan of small cove on smooth sheet. 



