CHAP. XXL] BOATS FOR SOUNDING 505 



The following points should then be attended to : To obtain 

 the best results there should be as few alterations of course 

 as possible — i.e., the hues of soundings to be run should be long 

 and fairly straight. 



An assistant, together with a signalman, to be specially 

 detailed to concentrate his attention upon each boat from the 

 ship, recording all times, bearings, and signal hoists in a book 

 kept for the f)urpose, whilst the sounding in the ship proceeds 

 uninterruptedly, the speed being regulated to suit the boats, and 

 alterations of course to be signalled in sufficient time before- 

 hand. 



The boats, whilst remaining approximately on either beam 

 and maintaining the course du^ected, in other respects control 

 independently their own movements, in order to preserve 

 approximately their correct distance and stop to sound as 

 often as may be necessary. 



The boats should not range bej^ond easy visual signal 

 distance — say, half a mile — and display by hand successive 

 numeral flags up to 99 (when the series is repeated) whenever 

 they require to be observed from the ship, at the same time 

 observing the masthead angle and the time, etc. The ship, 

 when answering each boat by a particular signal — distinguished 

 by the position from which it is displayed — then observes the 

 boat's compass bearing and the number displayed by her, the 

 fix being further identified by the time. The boat's traverse 

 can be subsequently plotted from that of the ship, and the 

 soundings filled in, the assistant on board being responsible 

 that the entries appear in their correct positions, and can be 

 identified with regard to the ship's traverse as the plotting 

 proceeds. 



This system has been found to work well, and can be used 

 with advantage in open off-shore or bank work, when the boats 

 would be otherwise unable to fix owing to the distance of the 

 objects, the difficulty of distinguishing them, or when out of 

 sight of land, etc. A range-finder can also be usefully employed 

 from the ship when observing the boats. 



Caution. — In addition to the usual precautions (signalling 

 by day and night, extra provisions, etc.) it should be an in- 

 variable rule that all boats when detached from the ship, under 

 conditions that render them liable to rapid exposure on a 



