Canvas 2 : In rowing, a "canvas" is the distance between the bowman and the bow, or between the coxswain and the stern. These areas were once covered by canvas. Winning by a canvas in rowing is analogous to winning by a head in a horse race
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}