Voyage Length

Perhaps the first essential is to define the word “voyage” since this can mean different things to different people.  The main point is to ensure that you always work in the same way to avoid confusion and it is recommended that the commencement of the voyage should always be from the time and the place where the ship completes discharge of the previous cargo.  In this manner, the first part of the voyage will be a ballast leg unless you are lucky enough to find a cargo out of the port in which you have just discharged.  Some people, including Worldscale, commence the voyage at the loading port and follow the laden passage with a theoretical ballast back to the loading port again.  However while this might at times be realistic for tankers, dry cargo tramp vessels rarely proceed on the same voyage twice so this is hardly a practical solution. With distances to hand, it is not difficult to estimate the length of the sea passage including the ballast leg. Working out the time spent in port can be a greater problem. Tankers are relatively simple as most tanker charters include a standard 72 hours all purposes laytime but dry cargo voyages vary enormously in their port time content. The snag is that you cannot usually calculate the port time until you know the cargo quantity; you cannot calculate the cargo lift until you know the bunkers which you cannot work out until you know the port time, which you cannot…….. and so on and so on.  Fortunately, dry cargo vessels do not consume much fuel in port and this can be safely ignored for the purposes of initial cargo calculations. Sometimes there are alternatives and only a marginal difference will tilt the pendulum in favour of one or the other.  Bad weather at certain times of the year; high canal tolls on one route; cheaper bunkers on another.