Tomorrow, race seven of the Clipper 2002 series gets underway with the 925-mile leg from Yokohama to Shanghai.

The eight international yachts will motor from the Bayside Marina in Yokohama to the start line in the south of Tokyo Bay and racing will start at 14:00 local time (05:00 GMT).

The stretch from Yokohama onto Shanghai will see crews contend with the notorious Kuroshio Current, which can reach a speed of four knots, as they embark on a south westerly course as far as the southern tip of Kyushu Island, some 500 miles away.

The tactical interest is heightened by the main current having counter currents close inshore. Additionally the yachts will be influenced by the strong tidal streams which can be powerful around the five main headlands they will pass. To avoid an adverse currents a sailor might nip into the bays between these headlands, but this is not always an option for the Clipper fleet in Japan. Many of the bays have fish farms and nets, some supported by strong chains which can snag a yacht.

The Clipper yachts could go further out to sea, but this will add to the distance and they will have to cross the 30-mile wide adverse current. This could still be a good option especially if those inshore suffer from another racing hazard, namely calms. All eyes will be on the fleet to see which yachts beat along the coast, or head out to sea where they will be clear of the current, the coastal shipping and the fish traps.

The first boat to reach the southern end of Kyushu could well be the winner of this race, as the final 400 miles are almost due west to the mouth of the Yangtze River and there will be little a chasing team can do tactically to gain on the leader. Even so, these matched yachts have been known to cause many an upset in the closing stages of racing and the Clipper 2002 event, in particular, is proving to be especially close.

After six races and four different winners so far, Jersey currently lead the overall Clipper 2002 standings on 39 points, with Bristol chasing hard on 34 and London not much further behind on 31 points.

The fleet is now moving out of oceans, back into seas, and crews will wave farewell to the Pacific as they pass Kyushu and enter the China Sea.

Once over the finish line the yachts have a 110-mile passage to Shanghai. The frontrunners will initially proceed to an anchorage to await the other yachts and the Chinese pilots who will escort the fleet as a whole up the Yangtze River. Race seven’s winning yacht is expected into Shanghai on Saturday, 22 March.