The fifth leg of the Volvo Ocean Race, from Rio de Janeiro to Miami, starts tomorrow (9 March) at 1.30pm local time, 1630 GMT.

The 4,450 nautical mile leg, which will take the fleet approximately 19 days to complete, will involve racing through the trade wind belts of the north and south atlantic oceans which are separated by the windless doldrums.

For the first part of the leg, to the north-east corner of Brazil, the fleet will have to battle against the trade winds and the Brazil current. Here the navigators face their first choice: they can elect to go offshore, but in doing so, will sail a longer course, the possible repayment being stronger and steadier winds. Or, alternatively, if they decide to stay close to the coast, the thermal effects of the day and night may help with lighter, more favourable winds. The strength and position of the current will also play its part in the decision-making process.

From the north-east corner, the wind should become more favourable, allowing the fleet a choice of where to cross the equator and then pass through the doldrums. In the western atlantic, the doldrums are usually fairly narrow, so the passage through should be quick and painless, just a narrow band of squalls and calms before finding the north-east trade winds on the other side. The equatorial current will also be giving them a helping hand as they head towards the Caribbean.

Perfect sailing conditions should be found as the fleet passes the West Indies, where the wind will vary between the south-east and the north-east, blowing mainly at 15 to 20 knots or Force 4-5.

Once past the Bahamas and towards Miami, the wind is likely to become more variable for the final approach and for the crossing of the gulf stream. With luck, the wind Gods will be smiling and the the trade winds will hold all the way, but the gulf stream can become rough if a cold from from the USA chooses the same time to sweep down from the north-west. These fronts appear quite regularly, and it will be a matter of chance as to whether one coincides with the fleet’s arrival. With a strong northerly wind against the fast flowing current, steep breaking seas can quickly develop, requiring the crews to treat the final few miles with respect and caution. After four legs of the Volvo Ocean Race, and with five stages still left to race, illbruck, with her American skipper, John Kostecki, has a clear lead of seven points over her nearest rival, Grant Dalton and his team, including two Americans, onboard Amer Sports One. But, breathing down Dalts’ neck and just two points behind, on a total score to date of 20, is Assa Abloy, with Neal McDonald in charge. McDonald has boosted his crew and now has four Americans in the crew line-up.

The next three teams have just one point between them: News Corporation in fourth overall on 19 points, just one point behind Assa Abloy, Tyco with 18 and djuice with 17. Five points behind djuice is SEB, who did not finish leg three, from Sydney to Auckland, and leg four from Auckland to Rio de Janeiro, due to rudder and rig failure.

With seven points is Amer Sport Too, led by Lisa McDonald. This team is pushing hard all the way and, with the crew becoming more and more familiar with their boat, this team is gaining strength day by day and is now in a position to engage in serious battle with the seven other contenders.