Green’s Dictionary of Slang

(US) any form of ‘fixed’ sporting contest.

1917		in R. Peyton At theTrack (1987) 150: There were rumors that a ‘boat race’ was being contemplated.
1929		D.H. Clarke In the Reign of Rothstein 110: The Jockey Club has killed off ‘boat races,’ as crooked races are termed.
1931		D. Runyon ‘A Nice Price’ in Runyon on Broadway (1954) 188: The only boat races I ever see are those that come off around the race tracks, [...] being a race that is all fixed up in advance.
1938		D. Runyon ‘The Lemon Drop Kid’ in Runyon on Broadway (1954) 372: It is nothing but a boat race, and everything in it is as stiff as a plank, except this certain horse.
1945		W.R. Burnett Tomorrow’s Another Day 50: ‘I got a tip,’ he said, ‘that the Greek took an awful pasting on a boat-race that slipped’.
1945		W.R. Burnett Tomorrow’s Another Day 185: ‘[A] lot of ugly rumors have been going around about this race. I’ve been told a dozen times that it’s a boater. Nobody seems to know who is supposed to win, but everybody seems to think there’s more here than meets the eye’.
1956		‘Toney Betts’ Across the Board 150: For a ‘boat race’ Mahoney ruled seven steeplechase jockeys and a trainer off for life, and gave an agent a year’s suspension.
1969		Current Sl. IV:1 4: Boat race, n. An event arranged only for show. A ‘fixed’ fight.
1993		M.B. ‘Chopper’ Read How to Shoot Friends 179: I would hardly say to the stewards: ‘Hey, we had a boat race going on in the fourth, could we declare it a non-race?’.