East or West? Downwind, or wind of the direct road? For Cowes-Cherbourg, the last race of the OCRN season (the very British Royal Ocean Racing Club), I found my Russian customers of the Morgan Cup on board their proto Mills 37 Thunder II. In the tide of whitewater, and with moderate to low winds, the strategy would clearly give priority to the influence of tidal currents. Starting from Cowes with the flow (eastward), before suffering an entire tide of ebb (westward), knowing that the current is stronger on the French coasts than north of the Channel, and that on the other hand the West wind was going soften in the course of night , the routing software suggested dropping under the wind of the road, under zero code or asymmetrical SPI as long as the breeze held, finally letting itself be winded by the current, on a rather loffée trajectory in order to improve the apparent wind.
But this is: as Jean Yves Benoit, Big Manitou, if it is the strategy in the race, a routing chart "is not a railway timetable to follow the letter", just a decision support. To take a closer look, the software planned an arrival in Cherbourg pile at the time of the tide, combined with a wind rotation to the southwest. No need to be a great clerk to understand that if you landed late on this beautiful planning everything would be to review. It was possible to imagine several reasons for this possible shift: from the polar (boat speed chart for each angle and wind force) optimistic (*), performance in slight setback on the capabilities of the boat and crew, a wind a little Less sustained than expected, or a lag in the weather forecast.
With ultra-sharp software like the browser, the navigator can play on a multitude of variables: percentage of polar efficiency, percentage of the actual wind force relative to the forecast, change in weather forecast in terms of timing As the precise direction of the wind, etc. The application for IPad Weather4D 2.0 is by nature more limited in its functionality. To simulate a pessimistic scenario and test the strength of the initial routing, I simply delayed the start of the race by two hours. An almost opposite strategy has emerged, consisting of staying high on the course to finish by letting itself be carried on Cherbourg by the beginning of a sustained current in the east, and by banking a marked refusal of the wind.
Of the two trajectories, which one to choose? At the outset, plan B seemed more appealing, as it was understood that plan a, while shiny it appeared, could turn to disaster: large potential gains, but maximum risk, even unreasonable. The rest of the events would, in spite of us, strengthen our convictions in the Western option.
Initially in front of Cowes, we choose priority to the power of the bearing current, rather than to the best descent angle under SPI. Almost alone to pass north of the Rydde Middle bench, we have the satisfaction of leaving the Solent (* *) at the top of our class. Las, at No Man's Land Fort is the bottling with the smallest boats left ten minutes before us, it follows a collapsing of SPI earlier than expected, a little haste…. And the asymmetric SPI trawl. On the balance sheet, long minutes to retrieve it, and a damage on the telescopic end-out. A/The leaders have escaped and we will not see them again. b/Our SPIs will remain in the hold, we will no longer be able to use them. This time there is no more to at face value, we will remain even higher on the road that it is our only choice to keep speed under Genoa and that, for the moment, we are sure to sail below the performances announced by the Polars.
After taking a choice, it is necessary to stick to it, which is not simple when the crew regularly asks questions on the trajectory followed and the fact that irretrievably our route leads us to the cap of the Hague rather than to Cherbourg. While the wind is steadily softening, a last-chance tinkering allows us to establish the zero code on the end-out. We suffer in silence, because we know full well that under SPI it would go faster. Then bingo, in the last hours of the night the wind collapses and refuses, we end up close in all the little airs, the green lights of a whole fleet marching downwind in the right direction: we nibble and then swallow all those who had slipped in The east.
On arrival in front of the Central Fort of Cherbourg We deplore more than two hours late on the winner, the French J133 Pintia, but we finish at one minute on the heels of the third, the X41 British Soldier, which remains a reference since it finishes Second in IRC2 of the annual OCRN Championship. For my part, with this place of 4th Difficultly acquired and the second place at the Morgan Cup, the contract is fulfilled. In the aftermath, we open with the owner of Thunder II the reflections on the improvements to be made to the boat this winter, and on the training and race program of the 2019 season.
(*) The only good poles that are to be found are those that you build yourself, as you sail with your boat. For lack of recoil and suitable instruments on board the Mills, I work with the calculation tool IPolar, which provides a very good approximation… But that's still an approximation.
(**) The arm of the sea separating the Isle of Wight from England. The effects of current and wind are so marked and complex that it is a feast (or a puzzle) in regatta for Tacticians.