1364 HYDROGRAPHIC MANUAL PaGE 26 



1364. Subplans 



Sheets containing small detached areas of hydrography shall be avoided, if practi- 

 cable. This can usually be accomplished by placing a suhplan, or insert, on the 

 smooth sheet, at the same or an enlarged scale. (See 7751.) 



If it is impracticable to include, in the original sheet layout, an entire area on 

 several standard size sheets, and a small section remains that is necessary for effecting 

 a junction with a prior survey, it is frequently practicable to include such area as 

 a subplan on an unused portion of the adjacent sheet. Such subplans must always 

 be included on the sheet of comparable scale closest to the area. 



Where a small harbor, anchorage, or other area needs to be surveyed at a larger 

 scale than the remainder of the inshore coastal waters, it likewise may frequently be 

 included as a subplan on the sheet which includes the area. 



It is to be noted that boat sheets are not necessarily similar in layout to the 

 smooth sheets and there is no objection, and in many cases there is a decided advantage, 

 in surveymg on separate boat sheets such areas as are discussed under this heading. 

 The results of several boat sheets may be included on one smooth sheet. (See 3222.) 



1365. Layout Made in Washington Office 



Infrequently the sheet layout for the project is made in the Washington Office 

 at the time the project instructions are written, and is furnished with them. This 

 may occur when the results of the survey are urgently needed and it is necessary to 

 furnish the boat and smooth sheets to the field party without delay. 



It is also necessary if lithographic reproductions of planimetric maps are to be 

 furnished for use as boat and smooth sheets. 



To take advantage of the economy of lithographic reproductions it is often nec- 

 essary to sacrifice certain desirable features of layout. When a proposed layout, based 

 on planimetric maps, is made in the Washington Office, it will be submitted to the 

 Chief of Party for inspection and approval, if time permits, before the boat and spiooth 

 sheets are constructed. (See 733.) 



7366. Dog-Ears 



It is sometimes impracticable to determine in advance the exact limits of a hydro- 

 graphic sheet. Because of developments during the progress of the survey or the 

 location of control, it is occasionally desirable or necessary to use a control station 

 which falls a short distance beyond the limits of the sheet as originally laid out. This 

 is accomplished by adding a small section of paper, called a dog-ear, to the boat sheet 

 and plotting the station thereon. While there is no objection to the use of dog-ears 

 on a boat sheet, there is serious objection to their use on smooth sheets, and they are 

 not to be tolerated on the latter except in an emergency. (See 7121.) 



137. Supplies and Equipment 



After the receipt of the project instructions, a review must be made to determine 

 whether the necessary survey equipment and instruments are on board, and if not, 

 they should be requisitioned from the Washington Office in ample time for their as- 

 sembly, possible overhaul, shipment, and receipt before needed for actual survey 

 operations (see 432). 



