Green’s Dictionary of Slang

1. a sailor.

1904		Kipling ‘Their Lawful Occasions Pt I’ in Traffics and Discoveries 126: Think o’ her Number One chasin’ the mobilised gobbies round the lower deck flats.
1918		Thames Star (NZ) 12 Aug. 1/3: No one has ever explained satisfactorily why they are called ‘gobbies’.

2. a coastguardsman.

1890		Scotsman 4 Aug. n.p.: When a meeting takes place the men indulge in a protracted yarn and a draw of the pipe. The session involves a considerable amount of expectoration all round, whereby our friends come to be known as gobbies [F&H].
1891		’Sailors’ Lingo’ in Hants. Teleg. 21 Feb. 11/3: Coastguardmen are often called ‘gobbys’.
1936		Mencken Amer. Lang. (4th edn) 574: The English coast-guardsmen, who are said to be free spitters, are often called gobbies.