HOW TO PLAN OFFSHORE VOYAGES

Choosing the best ocean route can be daunting. Jimmy Cornell explains how to do it, and how the parameters are changing

- Jimmy Cornell

Every voyage starts with a dream, and a voyage on my own boat to the remotest parts of the world was my dream as far back as I can remember. That dream became a reality in the early 1970s when I started preparing for a world voyage with my wife, Gwenda, and our two young children, Doina and Ivan.

The first step was to join a course on offshore navigation and it instantly turned me into a lifelong addict of that ancient art. This is how I learnt about the importance of pilot charts in voyage planning, and became my most useful source on weather conditions during our six-year-long round-the-world voyage. In those days there were no weather forecasts available on offshore passages, and the monthly pilot charts provided information on the kind of sailing conditions to be expected by showing prevalent wind direction and strength, percentage of gale force winds, currents, and tropical storms and their tracks.

The first pilot chart was produced by Lieutenant Maury of the US Navy in 1853 and showed the prevailing winds and currents in the North Atlantic. The early pilot charts were based on records obtained from the logbooks of captains sailing the North Atlantic trade routes. The data was displayed numerically, but were superseded by easier-to-interpret charts in which the winds were shown figuratively, as in this British chart of the South Indian Ocean of 1856.

INTERPRETING PILOT CHARTS