It's been a long speed contest for the four IMOCA racing to the northeast, away from the Brazilian coast. For over 24 hours they had been racing close to the wind on port tack, heading offshore. 

As The Ocean Race meteorologist Christian Dumard notes: "Very shifty and unstable unpwind conditions..."

But over the next 48 hours, the teams will need to transition into building easterly tradewinds which should carry them up to the doldrums. 

In these conditions, speed is king, and the fleet has closed up, with all four boats within 10 miles on the tracker leaderboard. 

"It's likely to be gusty but generally quite light," said Alan Roberts on Biotherm. "We have Malizia just a mile away, and GUYOT a bit further back and 11th Hour Racing just up in front of us..."

"The fleet has been compressing for the last few hours and I think it's going to continue to do so. These next hours are going to be key to get into the new breeze and starting the next phase of the race which is going to be reaching up the Brazilian coast."

As the boats sail away from the coast they are leaving two exclusion zones behind, a couple for some big oil fields that include a lot of installations and commercial traffic and one just off the coast, marking the Abrolhos Bank, a known area for marine mammals. 

Damian Foxall on the 11th Hour Racing Team sent some notes back on the reasons behind some of the nature-specific exclusion zones, including this one:

"We have one here called the Abrolhos Banks which is one of the zones where up to 25,000 southern Right Whales and Humpbacks come to from Antartica, where the warmer waters are, and to breed. We are a month away from this activity, but just to be safe, the organisers have defined this exclusion zone for us to sail around."

You can read more from Damian and about the exclusion zones on this leg here.

Meanwhile, Team Holcim-PRB have come up with a plan to sail the boat to Rio, under jury rig, where they will fit a spare mast and rejoin the race. The logistics and timings behind this operation are complicated.

But with support from the experts on the GAC Pindar operations team, Kevin Escoffier's crew and shore team are working on multiple potential solutions to get the mast from Lorient, France, to Rio in the most efficient way that will support a very tight timeline. The shore crew will help fit the new mast and the team intends to finish Leg 4 to collect at least one point and maintain its position at the top of the overall race rankings.

You can see the team working on the jury rig using the outriggers and boom and the storm jib here

Escoffier and his team hope to reach Rio on Saturday using this configuration.