The last 24 hours could not have been more contrasting. We’ve gone from sun to fog, from high jinks to low spirits, and from jockeying for third place we’ve slipped back down the pack.

Yesterday it was hard to remember we were in a race. After losing sight early in the morning of a faint triangle of sail on the horizon – our last view for the day of Save the Children – we had the sea to ourselves. The sun was out, the wind was light, and the Irish Sea was doing a fair impression of the Mediterranean.

The crew’s mood altered accordingly. Out came the shorts and sun cream, personal stereos and journals. It was a chance to catch up on laundry, to bake bread and brownies in the galley, and to plan the inaugural broadcast of Besso FM.

Last night was our turn to host the nightly VHF chat between the skippers in the fleet. This event is usually limited to a brisk exchange of the competing yachts’ longitudes and latitudes, but skipper Matt, who worked in Australian radio before he became a professional sailor, was relishing the opportunity to do something different.

“You’re tuned to Besso FM, broadcasting live from the Celtic Sea on Channel 77,” he drawls on the dot of eight o’clock as the music of Dire Straits ‘Money for Nothing’ fades away. The listening skippers find themselves forced to adopt the role of personal callers to our imaginary radio station. Some of them are nonplussed, most take it in good spirits, and one or two even manage tart ripostes to Matt’s gibes.

After all this hilarity it’s hard to snatch a couple of hours’ sleep before going back on watch at midnight, particularly with the generator thrumming away in the background, producing power for the boat’s watermaker. All too soon, though, we are roused to go back on deck.

During the day, the notorious Irish Sea had been a sleeping giant. The only indication of its latent power was the surface swell, like muscles rippling beneath the skin. That night, the giant begins to stir.

‘Tonic’ watch emerges to learn that, some 40 minutes earlier, Besso passed the race’s first waypoint, Alpha, an imaginary point off the west coast of Ireland. We also find the spinnaker aloft. The yacht is flying along at nine and half knots – in thick fog.

Keeping the boat under control in these conditions is thrilling, but a little too much on the scary side of exhilaration for comfort. Before we know it, visibility has shrunk to 50 metres. It’s far too dangerous to keep the spinnaker up: at this speed, the sail gives us little room for manoeuvre. We could be upon a fishing trawler before we know it.

Getting the spinnaker down, though, requires the assistance of several members of the off watch. It’s not quite all hands on deck, but close. “Imagine this is Def Con 4,” barks Matt to instil the proper urgency. It works. The sail comes down perfectly and is poured down the hatch in gathering folds.

We are soon back up to speed under our new set of sails – No. 1 yankee, staysail and main. And our course is much closer to the rhumb line: we’re keeping to a more accurate heading. But the experiment with the spinnaker has cost us several places, leaving us to reflect on the day and night’s ups and downs, and learn from our mistakes.