Sunday promises what could be the most exciting Global Challenge race start to date, with a potential autumn gale to send the 12 yachts on their way from Portsmouth at 1400. The combination of a restricted start corridor and a forecast of wet and squally conditions could produce a classic, spray-filled upwind start for the fleet as they race west to Gurnard and out through the Needles Channel.

A low pressure system is due to arrive over the UK on Sunday, which will bring 25-30 knots of wind. The sea state in the Solent will increase throughout the afternoon as the tide is westgoing.

“We know that this warm sector is going to come over us, but the uncertainty really is the timing,” says Challenge Business’s managing director Simon Walker. “At the moment the model we checked had the front well and truly over us at the start.

“However, the secondary low that’s forming is a way out to the west, so a small delay of only a few hours might mean that, although it’s going to be quite breezy, it might be still be cold sector weather and be more stable. If the front goes through earlier then we just have the squalls to worry about. Also the pressure gradient north to south very quickly decreases, so if it just nudges a little further up, it will still be pretty damp but there might be considerably lower wind speeds.”

If, however, the front arrives as forecast at this stage, conditions will be pretty grim, with heavy, low cloud and poor visibility. “There will be consistent heavy rain and it will be really quite blustery,” says Walker. “And with wind over tide and spectator boats around it’s going to be bumpy.”

Rough weather would not change their plans for the start, Simon Walker states. “The only thing that would actually stop the start is fog, but that is not forecast. But there may be a postponement if a squall comes through and visibility completely and utterly closes down.”

Besides wind and rain, the 12 crews will also have to contend with a relatively short, fixed line from just off Southsea Castle to an outer distance mark that would be favoured if the wind is south-westerly. Once the gun has fired, they will have to tack west along a start corridor marked by large inflatable buoys. “The corridor is rectangular and to the north and south are obstructions in the course, so yachts can call water to tack back into the corridor.”

With tide under them, the crews will have to judge their start carefully. If they are over the line early (OCS), they won’t return, but will carry on and once outside the Needles Channel will have to do a 720°. For a blatant OCS of 5 seconds or more, the penalty is to wait outside the Needles for 20 minutes after the last boat.

“Talking to the skippers this morning, from a racing point of view they want to be well up there, but they are going to make a judgement call on the morning on how close they want to be,” says Simon Walker. “Obviously the first boat over the line, if they’re on the right side, is also going to be the first boat to call for water and tack across the entire fleet.

“We have practised the start a number of times on the qualifying sail because we wanted to learn about this limited space and they’ll be fine. But I think they’re all looking forward to getting into the wider Solent.”