As the rain and wind lashes against our office window I have to say nothing would appeal less than jumping in a rowing boat and setting off across the Atlantic! But this January this is exactly what adventurers Alastair Humphreys and Mark Beaumont will be doing.

Renowned for their round the world solo cycling expeditions, both Alastair and Mark are swapping their bikes for rowing boats and setting off with different teams to row across the second largest ocean on Earth.

Joining two other Brits and one Slovenian, Alastair and his crew will attempt the 2500 nautical mile crossing from the Canary Islands to Barbardos, each hoping to raise funds for their chosen charities.  Knowing that Alastair suffered from sea-sickness on his last, much smaller sea adventure - he rowed across the English Channel with injured serviceman Phil Packer for charity in 2009 - I was more than surprised when he told me of his plans to row an entire ocean!

“I vomited the whole way to France with Phil. But just for the final hour I emerged from the fog of misery and thought how awesome it was to be out at sea in a little boat.  I've wanted to row an ocean for ages - the physical and mental challenge, the emptiness, the simplicity. If anything will make me appreciate normal life it's being out there on the ocean for a couple of months. I can't wait!”

The emphasis for Alastair and his team is to inspire others by completing one of the most arduous challenges on Earth.  The crew of four will row in two hours shifts, 24 hours a day, and expect the challenge to take them between 45-60 days.

Follow Alastair Humphreys & the Tusmobil TransAtlantic team

Mark meanwhile is attempting to break the mid Atlantic ocean rowing record.  Joining a team of six ocean rowers, he is attempting to complete the 3000-mile crossing in under 30 days - the "four-minute mile" of ocean rowing.

Setting out from Morocco, Mark’s crew will also row in 2 hour shifts, and will need to maintain a speed of 3.9 nots for the whole of the expedition to break the record.  To make this possible, each crew member will need to consume between 5000-6000 kcal everyday, as they will be expending around 12 000kcal in a 24 hour period.

Follow Mark Beaumont and the Atlantic Odyssey team

Alastair and his 4-man team will row from the Canary Islands to Barbados (B to C); Mark and his 6-man team will row from Morocco to Barbados (A to C)

Rowing an ocean is one of the greatest feats of endurance on Earth.  Far more people have reached the summit of Everest and been into space than have rowed across an ocean.  Alongside the sleep deprivation, salt sores and the physical extremes, one of the biggest difficulties the teams will face will certainly be the mental challenge, as Alastair explained in his blog before he left:

“I know that at times I will be tired or demoralised. My arse will hurt...and the end will seem far off. I will be at sea with three virtual strangers. I know that our bond will grow into a strong team willing to help each other and work hard for each other. But before we arrive at that stage my motivation must really just be for myself.”

Good luck to both teams - we'll be following safely from our dry, still office!