Green’s Dictionary of Slang

bucket afloat n.

a coat.

1859		Hotten Dict. of Modern Sl. etc.
1873		Sl. Dict.
1927		Shields Dly News 2 Dec. 2/7: I put on my ‘German flutes’ (boots) and my ‘bucket afloat’ (coat).
1960		J. Franklyn Dict. of Rhy. Sl. 44/1: bucket and float Coat [...] in the army during the 1914–18 war.