The big news of yesterday was the introduction of an ice gate by Race Director Jack Lloyd. Designed to take away the temptation for the teams to dive deep south in the search for better pressure and a better angle to Cape Town. The Ice Gate is placed at 42 deg South between 20W and 10W, seen on the screenshot below.
Over the past few days the weather models are now in better agreement, giving a more reliable forecast and therefore more reliable routing options for the teams. This allows them to commit to a certain path to dive South, although how far South is still unclear. In the screenshot below is an ensemble routing of GFS 1.0 deg, at 0600UT this morning. The top of the red box depicts the ice gate, to be left to Starboard. I made it into a box so it is easier to see.
The addition of the ice gate reduces the options for the teams, which is good news for the front runners and bad news for the teams behind. What we will likely see is the fleet sailing along this ice gate in order to be as far south as possible, in order to make the most of the left shift on Saturday afternoon.
An ensemble GRIB is a really useful tool for gaining confidence in a weather model and its reliability. Ensemble GRIBs are currently only available through the American GFS weather model, and gives the end user (i.e. the navigators on board) the breakdown of the 20 different forecasts that make up the end GFS forecast we all normally see, downloadable via Squid or uGRIB etc.
Once we have all 20 breakdowns we can then do routings on each one, as you can see in the screenshot above. If the routings are scattered, you have little confidence in the forecast, and therefore the best option is to stay middle of the road. To be conservative and with the rest of the fleet until the model becomes more aligned.
If the forecast is debating between two options, split with 10 routings going South and 10 North for example, then you know one of two scenarios are going to play out. Or like now when every single one says to get South within the next 100nm, you can be confident that this is the way to go. Over the last week Dongfeng and Alvimedica seem to have played this conservative, middle of the road game well, and in doing so have made gains on the front trio.
It is interesting to note how DFRT and Alvimedica made these gains. In the last blog I spoke about trying to cut the corner to Cape Town, sailing closer to the Saint Helena high, in lighter winds, but sailing less distance. Over the last few days we saw Abu Dhabi and Brunel make big gybes out to the West, accepting the loss and that they had gone too close to the High Pressure. This allowed the others to eat into their lead. It must have been a painful call for the navigators on board, sailing almost exactly 180 degrees the wrong way to Cape Town! Mapfre and SCA appear to have gone too far West, and paid the price for sailing too far. Who would be a navigator?!
We are now perhaps into the final plays of Leg 1 and its good news for us fans that we have 5 boats back in contention. Dongfeng and Alvimedica need the others to make mistakes and for them to time their gybes over the next few days perfectly to take the lead, but a podium is on now if they get these next decisions right. Alvimedica seem to have found some great pace over the last few days it is worth noting.
So keep an eye on the boats gybing South over today, and then crucially when they time their gybes back to the East to not infringe the ice gate, that is the major decision over the next few days. The boats out West are coming in hot, with Brunel currently leading the way to the East. If Brunel can make their shortcut stick (not gybing West as much as Abu Dhabi did) then they could hold the lead for the next few days. What is exciting for us is that with 6-8 days to go, the race is now a 5 boat contest!