sentences:  This is of particular importance in Head of the River (time trial) races where the crews race line astern and so performance of other crews cannot be easily gauged.It is also critical to assisting the coxswain in sticking to the race plan, which usually involves strategic changes of rating.The amplifier is linked to one or more loudspeakers along the boat making it easier for the crew to hear commands, this is particularly important for the rower in the bow seat as they are often furthest away.