By Dan Topolski, Rowing Correspondent for The Observer and former Oxford Coach

There is a single moment in The Boat Race when it is won or lost. Maybe two key moments if you’re lucky enough to get a second chance, which usually happens because the opposition has failed to capitalise on a decisive moment of their own.

It comes in different guises: it may be a stroke, a crew’s position on the course, a tactical move or a mistake that provides an instantaneous breakaway chance. But what is essential is that a crew collectively and instinctively recognises and reacts to that fleeting instant as one. They all need to know that it is a vital tactical window of opportunity that stands apart from all the other instructions, encouragement and general noise emanating from the cox and supporters along the banks.

So what creates, and what are, these critical moments? Obviously the bends and configurations along the course itself play a significant role in the planned tactics set out by the coaches. But there are also the unplanned, unpredictable effects of the weather which mitigate or influence these decisions and provide other instances to take into consideration: the speed and strength of the incoming tide which is affected by recent rainfall; the roughness of the water which is governed by the direction and force of the wind – where it is against the stream at some points of The Race and with it at others. These may coincide with the bends or may occur at different places on the river. Whatever the fleeting moment is, the crew has to be ready to make its killer move.

There are a number of places in the four-an-a-quarter mile (7km) course where that move can determine, or change, the outcome of The Race and the coaches of the two crews will have prepared their men to defend or attack depending on where the advantages and disadvantages occur along the tricky winding Tideway course. So with both crews well prepared and briefed to anticipate where those vital points are, the chance of pulling a fast tactical move is rare. Oxford and Cambridge locked in battle are like two boxers sizing each other up in the ring.

So where are those key places where the crews will try to steal a psychological advantage? Generally the essential tactical spots coincide with the four bends on the course. Two of them – the Surrey bend at Hammersmith and the Middlesex Barnes bend in the last mile – are worth as much as three-quarters of a length to the crew on the inside station unless the outside crew can nullify some of that advantage. A sustained high pressure couple of minutes can contain an inside crew expecting with little extra effort, to gain a few seats and that can raise their motivation while sapping the confidence of their rivals. The other two bends are worth a quarter of a length each. The Fulham bend assists the crew on the Middlesex station two-and-a-half minutes into The Race as they pass Fulham Football Club. It comes early – soon after the crews have settled into their race rate after the intensity of a high-powered start. Unless one or other crew has made a mistake in the opening effort, this bend is spent jockeying for position with the Middlesex crew trying to steal a lead which will provide an edge to cushion them further down the course when they encounter the long four-minute Hammersmith bend against them.

At the same time, the defending inside Surrey crew will be determined to contain their rival’s advantage and prevent them from opening up any clear water. The danger is that going half a length clear would allow the Middlesex crew to move in front, take the best centre-stream course and wash down the trailing crew with the puddles from their blades. This secenario rarely happens nowadays with crews trained by professional coaches who, experienced in the latest psychological techniques have brought their crews to a perfect peak at the right time. But in the not-too-distant past some Races were decided as early as this first mile when an occasional outstanding crew could outpace and out-power their less talented opposition.

Clearly, the coxes have a vital role to play as they battle to hold onto their share of the elusive fastest stream for their crew. Artful and judicious steering by the cox of a crew on the outside of a big bend, to hog as much of the stream as possible, is also a strategy. But running so close to the edge of legality is likely to attract the wrath of the Umpire. The cox will be gambling that the Umpire may judge his or her chosen course to be correct – especially if the cox of the inside crew is giving way. Possession is nine-tenths of the law, and aggressive coxing has been known to pay off handsomely at these key moments. The Umpire is there to prevent the crews from clashing or obstructing each other’s course, not to protect them or guide them over it.

The cox can also occasionally decide the outcome of The Race by making a split-second decision when confronted by strong wind and waves or a slackening tide. Heading for the protection of the shore and flatter water, or cutting a corner, can give the crew an unexpected advantage. But it can also prove a disastrously wrong move.

Mistakes can be made – especially in rough conditions. All eight rowers, not just the cox, need to spot one in the opposing crew and exploit it, even though they are locked in their own bubble of pain, intent on their own effort. These are the gut instinct reactions familiar to a true racer – the immeasurable factor that separates the winners from the also-rans.

These crucial race-winning moments may last for just 10 or 20 strokes – maybe less than a minute – but the antennae of each crew member have to be on sharp alert. They are not just pulling. Every stroke has to be technically perfect and in absolute harmony; any misplaced movement is a disruption to the smooth flow of the boat’s progress. They have to stay cool under fire and make sure that all the months of training they’ve done creates the perfect performance. It’s high wire stuff. So, in the next Race put yourself in the boat and try to spot the crucial moment when the winners make their killer move.

(This article first appeared in the 2008 Boat Race Programme)