'To double-bank an oar' definitions:

Definition of 'To double-bank an oar'

From: GCIDE

Double-bank \Dou"ble-bank"\, v. t. (Naut.) To row by rowers sitting side by side in twos on a bank or thwart. [1913 Webster]
To double-bank an oar, to set two men to pulling one oar. [1913 Webster]