Possible Clues:

• Being abroad without cash means going without booze
• Not taking drink out - can's inside
• Can - missing round - be sober
• It's not for the present that one will not be indulging in about a can of this
• Sailors can have thrown net nowhere near the drink
• Avoiding port, perhaps, sailor's given home in temporary shelter
• Not drinking best at inn, after a ramble
• Sailors at home occupying temporary accommodation keeping off the rum?
• Metal blocks missing, evidently not tight
• On the wagon