Green’s Dictionary of Slang

1. to have a surreptitious nap; to sleep; thus n. caulk, a nap, a sleep.

1839		Cumberland Pacquet 26 Feb. 4/1: ‘Where do you hang your hammock to night [...] I suppose you caulk off where all your trade do’.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
1887		G. Davis Recoll. Sea-Wanderer 261: The captain, coming on deck, and looking round and perceiving some of the crew ‘caulking’ (nautical, sleeping), said to me, ‘Mr. Davis, if you catch any of these black sons of b—s sleeping on their watch, take a handspike and knock their brains out’.
1887		G. Davis Recoll. Sea-Wanderer : .
1898		Dly Press (Newport, VA) 17 Apr. 2/2: 'Corking' is sailors' slang for sleeping. When they lie down on the deck, as they often do for a snooze, figuratively speaking, they are caulking the deck.
1918		‘Bartimeus’ Long Trick 81: ‘Wouldn’t you like to sleep a bit now, sir? [...] You can carry on and have a jolly good caulk’.
1939		‘Some Annapolis Sl.’ in AS XIV:1 Feb. 77/1: caulk off. Sleep, especially during the day.
1944		P. Kendall Dict. Service Sl. n.p.: caulk off . . . sleep.

2. to idle, to waste time on the job.

1898		H.H. Lewis A Gunner Aboard the ‘Yankee’ 88: There were times after mess when we could ‘caulk off’.
1900		Bulletin (Sydney) 3 Mar. 32/3: ‘I couldn’t help it. I was done when I got to the water; and I don’t remember anything until I came to myself about three or four hours ago.’ / ‘Done, indeed! You’ve done for me, curse you! caulking there while I was a-dying.’.