As I write this, Roxy is gingerly surfing the first waves of the Southern Ocean, as we get used to the pace of our new environment. This week I have had a reminder of how fragile our place in the Vendee Globe is; take your eye off the ball for just a second and your race could be over. It is the daily duty of every sailor to check, double check and triple check everything on board, as most potential problems can be stopped before they get serious. As I have a Masters in Mechanical Engineering from Cambridge University, I am better placed than most to tackle any problems. However, gear failure is my biggest worry, as although I am quite a good MacGyver, there are some things that you just can’t fix.

At the beginning of last week, during one of my numerous routine checks on board Roxy, I found that a part of my starboard rudder had broken. The piece in question was a custom-made titanium rod, whose function is to support the rudder and its casing.

There is no spare on board, as this piece should not break and never has done before. As I was on port tack, meaning the starboard rudder was in use, I would have had to stop to repair it. After some intense deliberation, and having spoken with my shore team and the designer of Roxy (Pascal Conq), I decided that the rudder could hold out until I reached the Saint Helena high pressure in three days’ time. There would be less breeze in the high pressure, which would mean that I could slow the boat down, fashion a repair and not lose too much time.

This gave me time to prepare for the repair and construct a replacement rod from scratch out of the spare kit I have on board Roxy. It is a race after all, meaning that down time must be kept to a minimum, without, of course, compromising my own safety or the integrity of Roxy. With this in mind, I put on my Bob the Builder hat and fashioned a threaded rod, cut and drilled two carbon fibre end plates, and selected the correct nuts, bolts, washers and tools for the job. It always fills me with an enormous sense of achievement when we work out problems in this way, however it also gives me more time to worry about the situation worsening, meaning I spent a lot of time afterwards stressing, checking and re-checking the rudder.

When the wind dropped and things flattened out, I was finally able to carry out my repair. Luckily, Neptune was smiling favourably on me and all went to plan, meaning I lost no time in the race. Remarkably, it also cured the tummy ache that had been bugging me for the last three days! It is bizarre to think that the worry of the rudder getting worse, or the broken rod jamming, could make me feel like that.

The rudder is now re-secured, but instead of a custom-fitted titanium piece, it just has my stainless steel rod holding everything in place. The rod is not 100 per cent snugly fitted to the rudder, but it is the best I can do with limited resources. It is now up to me to watch the rudder and make sure it doesn’t deteriorate again, while in the meantime making more replacement rods ready to be used if my repair doesn’t hold. After all, that rudder has got to get me all the way back to the finish in Les Sables d’Olonne.

I am now sailing with Roxy for the first time on my own in the Southern Ocean, known by French sailing legend and winner of the first edition of the Vendee Globe, Titouan Lamazou, as the “Land of The Shadows”. For the next month or so it is going to be cold, dark and rough as we pass south of 40 degrees latitude, into the "roaring forties" and potentially the "furious fifties". Roxy and I will get further and further away from land, civilization and help, and I know that as we dig deeper into the wild conditions, the stresses and strains on both of us will increase massively.

This is when it feels like the world we are in is so far away from anywhere else. I am gradually beginning to realise just how isolated we really are down here. I think this takes the term “self sufficient” to a whole new level!