398 



HYDROGRAPHICAL SURVEYING [chap, xviii. 

 By night. 



Green light for starboard helm. 



Red light for port helm. 



No light for amidships. 



If lights are waved, hard over. 



Fig. 80. 

 Helm. Red Flag. 



2 Turns 



u 



2 Turns °^ 



u 



Amidships 



6 



Fig. 81 gives signals for main engines : 



Fig 81. 



Main Engines. 



Yellow Flag. 



<c: 



sV 



Half Speed ^ 



o 



By night, a white light in starboard fore rigging for ahead, 

 and a white light in port fore rigging for astern ; the height 

 indicates the speed. 



