Head races are great opportunity to test your crew and gain experience for the regatta season ahead. They do however present a few very different challenges and different skill set, this is my take.
Weather is always a factor as head races are during the coldest time of the year and are often longer race distances so weather plays an even bigger factor. It is always better to be over dressed when heading to the start than under, you can always take it off. These Head races rarely have warm up areas, in most cases you only have the row to the start, where you are held under Marshall control often for 15 to 30 mins whilst the division is assembled ready for the start. This is the second reason to have warm clothes, making sure you don’t get too cold after warming up and before the start.
The next thing to take into account is, are you racing up or down stream? Check with the host club and/or the relevant river authorities, for example: https://riverlevels.uk and http://riverconditions.environment-agency.gov.uk
If you expect there will be a significant stream then this will need to be factored in to your race plan.
Warming up. For a head race can be tough. On the way to the start it is ideal to do some 1 minute pieces at sub race pace and some 10s at race pace to make sure you are able to get into a good rhythm. Being able to get into a rhythm is key to a good head race. This comes with practice and training. Develop a knowledge of your crews ideal stoke rate and sustainable pace.
pic by Tim Fenemore
The start, is a rolling start with each competitor normally given at least a 15 second gap, if you know or expect you're a quicker crew than the one ahead in the running order don't be afraid to allow a little more time and distance before you begin your chase, overtaking a slower crew can ruin your race, don't forget your time doesn't start until you cross the start line. The organisers will have set the running order with faster boats going first reducing the possibility of faster crews being hampered by slower boats but its is just their judgement. As your boat nears the start, begin to build the pressure and the stroke rate over 5 strokes avoiding a sudden increase in pressure, you should aim to hit the start line at your pre-planed "race pace" and settle into your rhythm as quickly as you can and commit to the race.
Rhythm is key to a good race and turns and bridges tend to knock you off rhythm, getting rhythm back is hugely important. Responsibility falls onto strokes person here, once the boat has lost momentum and pace, don't simply keep ploughing on, take the stroke rate down a notch, from for example 30 spm to 28, re-establish the leg drive strong finish rhythm before raising the rating back to "race pace". It is worst case scenario but not unusual to need to restart on the fly during your race, due to a collision or steering error. These things happen, whether you’re a novice or a Henley champion being able to recover from them and getting back into the groove is crucial. Practice your restarts during training, the cox or nominated boat leader takes control, one voice in the boat and in my crew's case the call is "whole crew..back stops..go!", then the "build up over 5" call, re-establish the leg drive, strong finish rhythm before raising the rating back to "race pace".
During the race the whole crew should know when the cox or nominated crew leader is going to call the pushes. Common calls are "push for 10', "heads up" and "send the boat away" a well timed and firm call are a great way to refocus the crew and re-establish commitment to the race. Depending on the length of the course most pushes are made 1/3rd in, and at or just after 1/2 way. Coming out of bridges and turns are also a great place to make a push.
The final stretch, somewhere in the second half of the race the crew need to know where the call to "wind up the pressure" will come. Find a bridge, a turn or simply a tree that you know will not be too early to begin and in final 250 meters "push for the line","empty the tank","final 20/10/5 strokes". Don't forget it should be one voice in the boat.