The "muscular Christians" of 19th century tradition passed the 12st mark in 1867, but it took another nearly 70 years to move up a grade to a 13st average in 1936. The well fed baby boomers born after the Second World War cranked it up a notch to a 14st average in 1976 and this year Cambridge missed ringing the 15st bell by only half a pound per man.
The heavier crew has tended to win, but over 80 times the lights have taken it. This time the Cambridge margin over Oxford is 13lb per man and if the Dark Blues win it will be the biggest disparity ever to have been overcome.
Harry Mahon, the vastly experienced New Zealander who is coaching Cambridge alongside Robin Williams this year, is quick to point out that you have got to pull all the weight along. "It's fine when you're going well at the start but it's possible for boat movers to become boat stoppers," he explained.
The sport is also absorbing a weighty paradox. It is apparent that as oarsmen and women get bigger and the weight differential increases between the best lightweights - limited in the men to 11st - and the openweights, the differences in performance are decreasing.
The world's fastest time in the coxless four was held by a British lightweight crew from London Rowing Club until it was beaten by the narrowest of margins by the British heavyweight crew who won the World Championships last summer.
Thor Neilsen, a coach who chairs the international technical commission, thinks that the introduction of lightweight divisions to the Olympic programme means the differences will disappear.
Sean Bowden, coaching Oxford this year, says that, if the physical restrictions were removed from the equipment, there might be no need for lightweight divisions. "With a 96kg weight for the shell and 55kg of coxswain to pull along, there is bound to be an advantage to the bigger crew in an eight, but this is an artificial restriction and if the coxless boats were tailor- made for the crew at whatever weight, who knows how fast they would go."
Bowden explains that by pointing to the power-to-weight ratio as the key element in rowing. "Roughly: to double your speed you must cube your power, so clearly you are not going to push them up to 18 or 19 stone. It just won't work."
When asked why even though his crew this year is 13lb a man lighter than Cambridge he is still picking the bigger men in his group, he says: "I guess as a coach you just can't help yourself."
He points out that Harry Mahon, as coach to Greg Searle, the first British sculler to win a world medal in the single scull, worked hard to cut Searle's weight without losing available strength.
Asked to take a view on his crew's apparent disadvantage in weight he says: "You learn that all sorts of people win races, and others who are good on the ergometer or the gym who don't. The winners are the ones who get the best out of what they have got and above all who race closest to their limit when it counts."
Boat Race crews
CAMBRIDGE UNIVERSITY: Toby Wallace (Jesus) 15st, Brad Crombie (Peterhouse) 14:7, Alex Story (St Edmund's) 16:1, Graham Smith (St Edmund's) 14:12, Marc Weber (St Edmund's) 13:8, Jonathan Bull (Emmanuel) 15:9, Stefan Forster (Peterhouse) 16:1, Paul Cunningham (Gonville and Caius) 13:6. Cox: Alistair Potts (Trinity Hall) 8:8.
OXFORD UNIVERSITY: Charlie Humphreys (Oriel) 12st 10lb, James Roycroft (Keble) 13:10, Jurgen Hecht (Keble) 14:11, Henrik Nilsson (Hertford) 14:2, Ed Coode (Keble) 14:10, Andrew Lindsay (Brasenose) 14:2, Paul Berger (Lincoln) 14:3, Nick Robinson (Lincoln) 13:6. Cox: Alex Greaney (St Edmund Hall) 8:7.Reuse content