17 REPORTS OF SHOAL SOUNDINGS


  1. Reports of shoal soundings must provide adequate supportive information in order that the Canadian Hydrographic Service will be able to chart such soundings.
  2. Shoal depths reported with insufficient supporting information may not be possible to chart or even locate in subsequent searches conducted by hydrographic surveys.
  3. In order that full use can be made of reports of shoal soundings, Navigating Officers are requested to note the following points regarding essential details:
    1. Obtain the position of the shoal depth by taking a position fix over it, as well as on each side of the shoal depth, if this is not practicable then provide the position of the ship with a bearing and distance to the position of the shoal sounding.
    2. Indicate the method used to position the depth, e.g. Radar, GPS, DGPS etc. and the horizontal datum of the position fix, e.g. NAD83, NAD27, WGS84, etc. It is helpful to mark the details on a chart, which will be promptly replaced by the Canadian Hydrographic Service.
    3. Number the position fixes and insert the time (time is important since the height of the Tide must be found in order to obtain the chart depth). Note the time zone, e.g. GMT, UTC, PST, etc.
    4. For digital echosounders, chart plotters, integrated sounder/positioning displays:
      • Use your cell phone, smart phone or digital camera to take a picture of the display or displays when observing the shoal position, or remote position of vessel if sitting over the shoal is not safe or possible, and when observing the least depth of the shoal;
      • Be sure the display shows a digital depth readout, the depth units, the date, time and time zone (if available);
      • On the MIRSS, indicate the draft of the transducer. If the draft is set into the sounder, so that depths read from water line, then also indicate this on the MIRSS;
      • For chart plotters, or integrated position and depth displays, be sure the position is in latitude and longitude to as many decimal places as the unit will allow.
      • For vessel positions remote from the shoal, indicate the estimated bearing and distance from the location where the picture of the position display was taken.

Mariners and shore authorities are reminded of the requirements to inform appropriate Coast Guard agencies whenever potential hazards to navigation are identified. Refer to Part 3 of the Radio Aids to Marine Navigation (RAMN) publication.

Authority: Canadian Hydrographic Service (CHS)