Steering problems have forced Olivier de Kersauson and his crew to abandon their attempt at the Jules Verne Trophy today. After repeated problems driving the giant trimaran Géronimo at high speeds, de Kersauson made the decision while off the north coast of Brazil, at 10°S, saying that he could not risk the boat running out of control in the Southern Ocean.

The crew are returning more slowly to Brest under sail, where they will investigate solutions. Sadly, however, the setback means their Jules Verne ambitions for this year are over.

Géronimo’s steering has been failing completely on occasions when the boat is sailing faster than 25 knots and flying a hull in beam winds. This morning and yesterday one of the crew dived to inspect the rudder, but found it clear. De Kersauson and his project team are concluding that the source of the failures is at the rudder bearings and has been caused by strong cavitation of water over the rudder.

Unusually for a trimaran, Géronimo has only one rudder on the main hull. Consequently it is the largest ever made for a fast multihull, some 4m deep. Last year, the team found that the enormous loads and several thousands of tonnes of effort exerted by it were causing the carbon rudder stock to twist excessively and it was strengthened.

In common with most multihulls, whose rudders have to work over a wide range of speeds, there was a significant amount of cavitation over the rudder, but it was put down to the effects of the propeller and shaft.

However, although the engine, shaft and propeller were removed prior to the Jules Verne start, the problem continued. Now it seems that this strong cavitation at speed in certain conditions is putting excessive loads on the rudder bearings, causing the rudder to lock and the steering to freeze. “It’s a guess,” admits project manager Louis-Noël Vivies, “but we think the problem is the mechanical consequences of the cavitation on the bearings, and it is an increasing phenomenon.”

There are, says Vivies, several remedies. One is to add fences to the rudder; the second is to design a rudder with a very different profile, even if that is slower in light winds; and the third is to have rudders on all three hulls.

The crew are bitterly disappointed, but it seems the team are sanguine. “It’s a very big boat, very powerful and it’s very new,” says Louis-Noël Vivies. “Nobody has experience of this type of boat; it’s the first time. And it’s the first time anyone has designed this type of rudder. We know we have to break some parts to get good reliability later.”

Once repairs are done, Olivier de Kersauson will set his sights on other records and will ready the boat for a Jules Verne attempt next winter. By then several other challengers will be ready: Tracy Edwards, Ellen MacArthur and Steve Fossett have indicated they are looking at next year as well. All will be hoping that if Bruno Peyron, who leaves tomorrow in Orange, breaks the record it isn’t by too much.