In shipping business, once the cargo quantity and the loading/discharging rates per day being offered by the charterers are known the port time can be estimated with some accuracy. As always, there are pitfalls because it is rare for weekends and holidays to count in dry cargo fixtures and these, coupled with notice time and weather delays, extend the port time before demurrage is likely to start.
Let us take an example: A vessel is to load 35,000 tonnes of cargo and the charter loading rate is 2,500 tonnes per weather working day of 24 consecutive hours, Sundays and Holidays excepted. If one divides 35,000 by 2,500 it will be seen that the loading time allowed to the charterers is 14 days. This, however, excludes weekends and if you consider the working week to be 5 days, the time permitted approaches 3 weeks. If allowances are also made for notice time and some weather delays, it will become realistic to allow 20 days in port for loading. If loading is to take place over a period of extensive Public Holidays – e.g. Christmas and New Year, or Ramadam – even more port time should be allowed. Needless to say, if the time allowed includes Sundays and Holidays (SHINC) less allowance will be needed, perhaps 15 days. Even with SHINC, there are inevitable delays in arrival, shifting, notice time, waiting for tides, etc. This system is quite adequate for most charters and, in general, the full time allowance should be put in the estimate and demurrage/despatch ignored. Unfortunately, nothing in shipping is ever simple and different criteria have to be used for what are commonly called “despatch” charters. In certain trades, it is well known that vessels habitually load and discharge well within their laytime and, indeed, shippers and receivers expect to earn considerable despatch. It is likely, therefore, that comparing two voyages where one is a charter of this nature will show an unnatural disparity. Regrettably, there is no short cut to knowledge in a case like this and a voyage estimator must be aware of the trades where fast turn-rounds are to be found. Only in such cases is it correct to estimate a lesser port time than allowed but, in that event, a suitable addition to the expenses must be made to cover the inevitable despatch bill.