ously while underway and every effort made to 

 record a continuous profile of the bottom, 

 (fig- 5-3). 



Figure 5-3. Recording the sounding. 



5-7 Marking the Echogram. — When a new 

 roll of recorder paper is installed in the echo 

 sounder, the data must be written on it with a 

 colored pencil. Time must be recorded on the 

 echogram every hour when the recorder is 

 operated at slow paper speed and every 30 

 minutes when operated on fast paper speed. 

 In addition to the time, the date must be written 

 at 0000, 0400, 0800, 1200, 1600, and 2000 hours. 

 Upon removing the roll from the machine, the 

 date must be written at the end of the echogram. 

 Any notations made on the echogram must be 

 made with a dark-red pencil, as the ordinary 

 graphite pencil blends too well with the finish 

 on the paper. A sample echogram is shown in 

 figure 5-4. 



5-8 Maintaining the Sounding Logs. — 

 Sounding logbooks are furnished by the Hydro- 



(jraphic Office for Navy surveys. Two sounding 

 ogs shall be kept, one for the odd numbered 



days and the other for the even numbered days. 

 Unless otherwise specified, soundings shall be 

 recorded in the log every 5 minutes. These 

 soundings shall be read from the echogram, 

 whenever possible, as recordings of soundings 

 by audible or visual (dial light) means are sub- 

 ject to many personal errors. Whenever a 

 change of depth scale is made or the recording 

 shifted to another machine, it shall be noted in 

 the log; e. g., "Changed to 0-600 fathom 

 scale," or, "Shifted to recorder No. 2." All 

 changes of course and speed shall be entered in 

 the log. When two or more ships are operating 

 together, hourly pelorus bearings and radar 

 ranges of the other ships shall be recorded. 

 Proper time notations must accompany all 

 entries in the sounding log. Local zone times 

 shall be used and time zone changes noted. 

 A sample logbook page is shown in figure 5-5. 



5-9 DEVELOPING SPECIAL SOUNDING 

 GRIDS. — Cruise instructions often call for 

 development of special sounding grids in speci- 

 fied areas. These grids may be run to collect 

 detailed sounding data over a little-known area 

 or to verify the existence or extent of some 

 doubtful feature, such as a reported shoal or 

 bank. Sounding grids are run with the major 

 number of sounding lines parallel and at least 

 two lines normal (perpendicular) to the major 

 development. The latter are needed to verify 

 the main-line soundings. Wherever possible, 

 the main sounding lines are run normal to the 

 general bottom contours. If sea conditions are 

 unfavorable, the track pattern may be modified 

 to avoid excessive pounding, provided the same 

 area is covered with lines of the specified dis- 

 tance apart. Unless otherwise specified, sound- 

 ing grids in oceanic areas are usually run with 

 lines five miles apart. Soundings are entered 

 every minute in a separate log used only for the 

 grids. Echograms are time marked every 30 

 minutes. 



5-10 Using Two or More Ships on Sound- 

 ing Grids. — When 2 or more ships are employed 

 in developing a special sounding grid, the 

 following method is used. One ship maintains 

 navigational control. All ships record radar 

 ranges and pelorus bearings every 30 minutes. 

 Soundings are entered in separate logs used only 

 for the grids. Navigational fixes are obtained 

 as often as feasible. DRT tracks are maintained 

 with half -hourly time notations; all changes of 

 courses and speeds, and information pertaining 

 to resetting shall be noted. A typical 2-ship 

 sounding grid pattern is shown in figure 5-6. 



5-11 Discovering Uncharted Features. — 

 During the course of oceanographic cruises, 

 uncharted bottom features such as seamounts, 



48 



H. O. 607 



