To improve the efficiency of hydrographic surveying operations on inland and coastal waters it is desirable to employ a parent vessel in the centre, with up to six side vessels running courses parallel to the parent vessel art distances depending on the survey scale. A simple equipment is described which allows the side vessels to maintain their stations with respect to the parent vessel by measuring the difference in the time of arrival between a radio signal and a sound pulse transmitted simultaneously from the parent vessel at regular intervals. The indicating unit also provides a permanent record so that if a side vessel should err from its course, appropriate corrections can be made when the depth soundings are plotted.
National Research Council of Canada. Radio and Electrical Engineering Division
Report (National Research Council of Canada. Radio and Electrical Engineering Division : ERB), no. ERB-783.