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Jules Verne Trophy weather
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| by Sylvain Mondon |
| Weather expert ashore, Sylvain Mondon has exercised his science of routing at Météo France since 1993. |
The week's weather round-up - The fifth week at sea
From the Pacific depression to the Atlantic anticycloneThe fifth week at sea for Groupama 3 began at the same time as the month of March, whilst there was still a third of the Pacific
to be crossed in order to reach the famous Cape Horn (final course mark before Ushant).
However, it wasn't going
to be easy, as the powerful disturbed system, which had formed along the East coast of Australia over the final weekend
of February, was traversing the Pacific at a speed of 45 knots. The winds at the core of this system were violent and
there were very heavy seas here. After envisaging making headway in front of this system for a while, once it became apparent
that her speed was scheduled to be slower, Franck Cammas and his crew were forced to adopt a more conservative strategy by
bending their course to the NE. The objective of this deviation from the direct route was to let the bad weather roll over
the top of them (gusting to 60/65 kts with 8 to 9m waves) and get sufficiently far away to the South of them, that they could
then set a course for Cape Horn again at the rear of this system.
It was a race against the elements at that
point, with the timing very tight for pulling this operation off. However Franck Cammas and his crew knew that they didn't
have another option. Despite the difficulty of the task, success was imperative! Indeed, by sailing at the rear of the zone
of bad weather, their room for manoeuvre was greatly reduced before the influence of the following system made its presence
felt with some very light headwinds.
The operation was to last for four days, during which time Groupama 3 demonstrated
her qualities in the strong downwind conditions (30/35 kts, gusting to 40 kts) and heavy seas (5 to 7m waves). The operation
was a success since at midday on Thursday the winds began to ease and the sea became calmer as Groupama 3 passed to the South
of Diego Ramirez Island shortly before crossing the longitude of Cape Horn. The Pacific Ocean crossing time proves to be remarkable
and is a measure of how well they've performed with just 59 more minutes than the record time set by Orange II, skippered
by Bruno Peyron, set over this stretch of the course back in 2005. Franck Cammas and his crew showed great prowess given the
rather unfavourable conditions over the final third of the course.
On reaching the southern tip of the South American
continent, the easing, heading wind ended up by catching up with the giant trimaran. The repositioning to the North on starboard
tack became compulsory at approximately the longitude of Cape Horn. In this way the first tack into the Southern Atlantic
took Groupama 3 closer to the shore, providing the crew with a fantastic spectacle late in the day on Thursday 4th March.
The following change of tack marked the start of a long phase of sailing close-hauled, with the sheets slightly eased at
times, for the first quarter of the "final sprint".
Indeed, the weather conditions encountered in the Atlantic
gave them no opportunity to make the same kind of high speeds as Orange II was able to maintain for several days in the same
area in 2005. Nevertheless, driven by a determined crew, Groupama 3's performance enabled her to make a long and rather effective
tack on port. With the winds oscillating between the N and NW along the edge of an anticyclone shifting towards the centre
of the Southern Atlantic, she was able to regularly maintain average speeds in excess of 18 knots on a highly favourable course.
Their 150 mile lead over Orange II on exiting the Pacific was transformed into a 350 mile deficit by the evening
of Monday 8th March. However, this separation could have been a lot bigger had Franck Cammas and his crew not made the
very best of Groupama 3's potential along the edge of the anticyclone, between the evening of Sunday 7th and the afternoon
of Monday 8th, through a series of tack changes. These multiple manoeuvres enabled them to extract themselves from the influence
of the anticyclone and above all to move across to a better position to deal with the next difficulty off Brazil, which will
be decisive for the next stage of the course.
Sylvain Mondon
Meteorological Engineer
Marine
weather forecaster
Météo-France
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