Eight days into the journey and we’ve run the gauntlet of the Southern Ocean, 7-metre swells one day and dead calm the next. Snow in the morning and sunshine by noon. Deafening winds followed by light breezes.

Without the ability to access a weather forecast, we are completely at the mercy of the weather gods. With only sails, the Alexandra Shackleton is totally reliant on the wind, an indifferent force which blows whichever way it pleases.

Just like Shackleton and his crew, we’ve had our strength tested time and time again. In high seas and gusting winds just steering the Alexandra Shackleton to stay on course requires a tremendous amount of strength and absolute concentration.

Now that we’re travelling through the Antarctic Convergence we’ve been ensconced in fog, making celestial navigation very difficult. Using the old method of compass, sextant and the stars, we require a clear view of the sun and the horizon to be able to accurately estimate our position. Clouds and fog work against us, so I fear our dead reckoning may be a little off.

While there’s no doubt that physical and mental strength is required (as is having the skills to sail and navigate), it’s being able to adapt to rapidly changing circumstances that is proving to be an invaluable trait. The ability to adapt was one of Shackleton’s true strong points. He was a man who was able to quickly change course and set a new mark when the old mark proved impossible.

Watching his vessel crushed before his eyes must have been a hard blow to bear. Stuck in pack ice, it finally gave way to the force of the moving ice and slowly sank.

Others may have given up hope at that point but Shackleton was able to turn his failure into one of the greatest survival stories in the history of exploration. He was an alchemist in that way – taking something of little worth and transforming it into gold.

One of the questions I am asked quite often is: “Why are you doing this?” When my clothing is drenched, my bones ache from being contorted into unnatural positions, my muscles are cramping up and the fetid stench of dampness, sweat and boredom hang in the air, I too have asked myself the same question! The truth is there’s no one reason why I’m here.

I’m here out of reverence for Shackleton. I’m here to test my resilience. I’m here to shine a light on the fragility of the Antarctic environment and the incredible creatures that call this great, white continent home. As an environmental scientist, I can see the world changing at breakneck speed. Just as we have had to adapt to everything this journey has thrown at us in order to survive, I feel that collectively as a society we must implement changes in order to live in a more sustainable way.  That’s why we’ve partnered with Fauna & Flora International, one of the world’s oldest conservation organisations.

I’ve been here many times before, but on this journey I’ve come to realise that I can’t live with or without Antarctica. When I’m here the familiarity and comforts of home seem mighty appealing, yet when I’m home I crave the primal nature of duking it out with one of the most hostile environments in the world. Shackleton was never cured of this affliction - he was hopelessly devoted to Antarctica until the very end.  I too am forever bonded to this part of the world and how could I not be? It’s taken a lot out of me, but it’s also given me so much.

Tim Jarvis as told to Jo Stewart aboard the support vessel Australis.