The 59-year-old rower Zirk Botha on February 9 passed the three-quarter mark in his transatlantic ocean row from Cape Town to Rio de Janeiro.

The transatlantic crossing requires him to row completely unassisted for about 90 to 100 days, over about 7 000 km, or 3 800 nautical miles, in often difficult weather and sea conditions.

He is the first person to attempt the journey, rowing alone and unsupported by any safety craft, and his pace is setting records that will be hard to beat.

He completed 3 000 nautical miles in less than eight weeks, which equates to a daily average advancement of 58 nautical miles.

On January 11, Botha was already one week ahead of his initially planned schedule, having travelled 2 500 km, or 1 350 nautical miles, at the time, after starting his journey in mid-December.

Botha on January 22 confirmed that he was two weeks ahead of schedule, with another 3 500 km, or 1 900 nautical miles, to go.

As Zirk now reaches the Brazilian coastline, he will have to navigate around Trindade Island, fishing areas and oil fields.

“I want to stay well north of Trindade Island and the fishing banks. The sea conditions will get worse over the shallows and there might be fishing vessels. I intend to pass inshore of the banks, have the north-eastern winds from astern and to pass just inshore of the Southerly oil fields.”

Engineering News previously reported that Botha, who is being sponsored by renewable energy company Juwi, had done a great deal of research on his route, as well as on finding a weather window, considering that wind direction was key.

His voyage is informed by a historical maritime practice going as far back as when Vasco Da Gama was travelling the seas. Da Gama used trade winds to his benefit. The same route and similar timing are used during the Cape to Rio yacht race.

Botha opted to use a closed cell foam open class design ocean-rowing boat designed by esteemed naval architect Phil Morrison.

The current norm is for ocean rowing boats to be built from marine plywood or in a fibreglass and epoxy mould. However, Morrison’s design uses closed cell foam laid up with fibreglass and epoxy resin.

The specific design incorporates honeycomb construction principles, which ultimately makes it strong yet lightweight. The boat is constructed like a life boat to self-right, meaning the boat will roll back upwards in case the boat is tipped in extreme weather.

The boat is 6.5 m long, with a 1.62 m beam and weighs about 550 kg, including all equipment, spares and food loaded. The boat is powered by two 12 V batteries connected in parallel with a combined 200 aH capacity.

Botha served 17 years in the South African Navy, during which time he completed three Atlantic crossings.