Time

Time is vital to the work of a dry-cargo shipbroker, whether working under time-constraints when negotiating charters; maintaining contact with, for example, principals, brokers or ship’s masters; calculating timecharter duration; or establishing estimated dates of arrival of ships. However, it is important to understand how time is “calculated”. On a global basis, “Time” can be said to start at the Greenwich Meridian, which passes close to central London and which is taken to be zero degrees or 0o. From this starting point, imaginary lines of longitude are drawn, westwards and eastwards, for 180o each making a total of 360o for a complete circumference of the globe. Thus, if three hundred and sixty meridians (or lines of longitude) are drawn from pole to pole at equal intervals, they will be 1o of longitude apart. Starting from the Greenwich Meridian and travelling eastwards (towards India), time “advances” one hour for every 15o of longitude. Thus, a complete circle of the Earth coming back to the starting point of the Greenwich Meridian, will take 24 hours (i.e. 360 ¸ 15) and time will have “advanced” by 24 hours, or by one day. Westwards from Greenwich (towards the United States) will have the reverse effect. One hour will be lost for every 15o and upon returning to the Greenwich Meridian, one day will have been “lost”. Where those tracing eastwards and westwards passages meet “half way round” at the 180o meridian (in the central Pacific Ocean) is located the imaginary International Date Line (or “IDL”) for short, which is not completely straight, taking minor deviations so as not to bisect small islands or affect land masses. Thus, by travelling eastwards across the “eastern hemisphere” from the Greenwich Meridian, local time advances hour by hour until 180o East or the “IDL” is reached, at which stage one is 12 hours ahead of “Greenwich Mean Time” (GMT for short). Moving in the opposite direction from the Greenwich Meridian across the “western hemisphere”, one “loses” 12 hours in reaching 180o west.