Sentence:  ... I came on deck, put down my own stock behind the rudder head and well out of the coxswain's reach, went forward to the <WSD>water-breaker</WSD>, and had a good deep drink of water, and then, and not till then, gave Hands the brandy. 
Meaning of the word marked with <WSD> tags:  A container for storing water on a ship or other watercraft.