Wielgosz, Mirosław; Wiśniewski, Bernard; Korwin-Piotrowski, Tadeusz
(Scientific Journals of the Maritime University of Szczecin, Zeszyty Naukowe Akademii Morskiej w Szczecinie,
2012)
Since 2009 the Polish Steamship Company has operating on its ships SPOS, which main function is receiving weather information, presentations of this information in the form of synoptic and wave maps with forecasts up to 216 hours. The second function of the system is ability to determine the Great Circle, rhumb line and navigation composite routes and the so-called optimal and recommended by the system route (Optimum High and Wide). Because for each of these routes it is possible to generate in advance ship’s position for one, two, three days and so on until the destination (usually the roadstead of the destination port), it is likely to compare the various routes. SPOS compares distances (NM), duration of voyages (days and hours), expected average speed, as well as date and time ship reaches the destination (ETA – Estimated Time of Arrival). The reliability of these data is dependent on the ship’s characteristics as a control object or ability to obtain the calm water speed (Vo) at full sea speed propeller revolutions, and reduction of vessel speed due to waves and wind. The third element affecting accuracy of a voyage plan in terms of initial estimations is the reliability of weather forecasts (waves, wind, currents, ice restrictions, fog, etc.)