Green’s Dictionary of Slang

(UK Und.) a form of river robbery.

1789

G. Parker Life’s Painter 184: Craft rig. A new and curious species of robbery practised upon the river Thames. Two fellows who dress and look like watermen, steal a boat, row down the river to meet the Kent hoys [i.e. a small passenger vessel] [...] They hale the hoys, and want to know who wishes to go on shore, and as sure as any lady or gentleman gets into their boat, in a very little time they will jump up and rob you.