Green’s Dictionary of Slang

keel-hauling n.

a flogging.

1837		Marryat Snarleyyow I 14: Yes, as sure as Mother Carey’s chickens raise the gale, [...] I’ll be down and get my breakfast, there may be keel-hauling before noon.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 162: keel-hauling a good thrashing or mauling, rough treatment, ? from the old nautical custom of punishing offenders by throwing them overboard with a rope attached, and hauling them up from under the ship’s keel.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.