By Mark Davies
Former Cambridge cox between 1992 and 1995
It is probably the question I have been asked more than any other - "What on earth does a cox actually do?"
Cambridge cox Kevin Whyman celebrates winning in 1997
Contrary to popular belief, a cox does not shout "in, out, in, out".
Equally, that is not to say that what the cox does involves any great science.
There are two parts to the cox's job - steering and coaching.
In any race other than the Boat Race, steering does not take an awful lot of nous.
The Boat Race is unique because it takes place over a course that not only twists and turns - unlike the 2,000m Olympic course - but does so on tidal water, where the pace of the stream varies, and conditions are never the same from one day to the next.
Plenty of people cox on the Tideway - London's principle rowing venue.
What makes life different for a Boat Race cox is that, uniquely over this stretch of water, the crews are side by side, with nothing separating them except the view of the umpire.
With the two coxes both vying for the same quick water, they have to tread a careful path between giving their crews the fastest conditions, and also the clearest run - which can sometimes have calamitous results.
It adds a dimension to coxing which makes it a lot more interesting than steering over a straight course - a bit like the Grand National fences at Aintree add a new challenge for a National Hunt jockey.
The cox's other role - common to all racing - is to ensure that the crew row to their potential.
This is much the same as being a football manager and being able to fine-tune during the course of a match.
Your crew, or team, knows what they have to do and have proved they can do it - but under pressure, and suffering from exhaustion, errors can creep in.
They do the rowing equivalent of reverting to a long-ball game when everything you have done in training has been to focus on passing in triangles.
With half the crew doing one thing, and half the other, the rhythm falls apart, and the race can be lost.
The cox has to recognise, through feel and vision, what is going wrong, why, and how it can be put right.
The difference between a good, efficient, stroke and a bad one is very small.
So a good cox can make all the difference, just as a bad cox can lose a race.
Does that make coxes the unsung heroes?
Not really, because 80% of races will happen as they do without the cox.
But for that extra 20% you have to make sure the right man - or woman - is in the boat.