Global Challenge yachts BP Explorer and Barclays Adventurer are racing neck and neck under spinnaker on Leg 4 towards Tasmania.

The high-pressure system in the Tasman Sea has started to move east, effectively opening the gate for the strong westerlies blowing uninterrupted across the Southern Ocean.

There is a high ridging east just south of Australia, and a well-formed depression deep to the south. The steep gradient between the two is intensifying the speed and strength of the westerly breeze in the compression zone as it heads for the Global Challenge fleet to welcome them into the open ocean.

When the yachts pass Tasmania, they will have a choice. If there is any south in the wind when they turn into the Southern Ocean, they may be tempted to tack back up north towards the continental shelf. South is the desired course however, and if the wind is from the west as forecast, all the teams will head for the great circle route to Waypoint Bravo, over 4,000 miles away.

Chatting from the boat about the conditions over the next few days James Allen, skipper of Me to You said: “We are currently approaching Tasmania, so as the wind is due to shift from the north through west to the south west we are concerned with avoiding the wind shadows. At the same time every mile east of Tasmania we sail is an extra mile we will have to head to windward in gale force winds once we are south of the island.”

The winds may be strong enough to reduce the damaging effects of wind shadows as the fleet passes, but Tasmania boasts ten peaks approximately 1,500 metres above sea level or more, capped by Mount Ossa at 1617 metres. The entrance into the Southern Ocean will be key for teams at the front, eager to protect their positions as Dee Caffari, currently enjoying 3rd reported: “Tasmania is well known for its wind shadows due to its rocky shores so we will be playing the game of giving the island a wide berth, but without sailing too much further and letting any of the rest of the fleet cut in on the inside of us.”

Positions

BP Explorer 5,781nm to the leg finish

Barclays Adventurer 5,781nm to the leg finish

Imagine It. Done. 5,784nm to the leg finish

Team Save the Children 5,792nm to the leg finish

BG SPIRIT 5,802nm to the leg finish

Spirit of Sark 5,805nm to the leg finish

Me to You 5,806nm to the leg finish

Pindar 5,810nm to the leg finish

SAIC La Jolla 5,813nm to the leg finish

VAIO 5,821nm to the leg finish

Team Stelmar 5,833nm to the leg finish

Samsung 5,842nm to the leg finish