Maritime Geography

Whether the management department or company becomes closely involved in such calculations or whether this problem is left entirely to the shipowner’s chartering department, it is important the  Ship Manager is fully aware of the process of voyage estimating.  If for no other reason, it is vital to understand how various pieces of data, supplied by the ship manager, fit into the process of evaluating the profitability of a proposed voyage. The first essential is to examine the subject heading itself.  “Voyage Estimating” includes both voyage and time charter trips, the latter are rarely as straightforward as they seem and the pitfalls will be explained in due course.  The word “estimate” speaks for itself and it is necessary to point out that ships do not run like clockwork; it is, therefore, impossible to calculate to perfection.  That is not to suggest that the aim should be less than total accuracy and it is essential to seek to achieve this and to test the accuracy of  the estimates against the final voyage results. For voyage estimating it is also essential to have knowledge of maritime geography, with particular regard to distances and load line zones.  There are several sets of distance tables commercially available which can be used, but to avoid absurd mistakes one should have a fairly accurate idea of the major world distances.  A useful method is to divide the world into areas, naturally this mainly falls into oceans, and then learn a number of strategic mileages across each area.  Alternatively, instead of actual distance one can think in terms of days steamed, and as a useful guide, a speed of 14 knots works out at almost exactly 3 days per 1,000 nautical miles.  On this basis, it is easy to remember that a transatlantic voyage from US Gulf to Rotterdam is 15 days whilst that from Hampton Roads to the same destination lasts for 11 days.  Under this simple system representative voyages can be calculated and memorised.  Provided you remember to correct the time for vessels of differing speeds, this should make the task considerably easier.