The objective of this paper is the study of the possible use of meteomarine forecasts for correct management of ships ballast water, in order to improve the safety of navigation, having in consideration the economical costs (wrong load/unload of water) and the possible environmental impacts that can be generated. The analysis has been carried out verifying the operative forecasts used for the training of the Italian Yacht "Consorzio Prada" for the America's Cup 2000 and issued in the period April-July 1999. Studying the forecasts quality, situations of potential incorrect load of ballast water has been examined and, consequently, the potential negative effects. It has been demonstrated, furthermore, how also a correct weather forecast is of paramount relevance for the safety of navigation, without economic loss and observant of the increasing important environmental aspects.
The introduction of ballast water has a crucial role in the performance growth of different types of craft (Buxton and Logan, 1986). At the same time, however, the sensitivity of these kind of crafts to the meteomarine conditions implies a more complicated management due to the decision to load or unload the ballast, in order to modify the trim of the boat (Bierk, 1996). From these considerations, it is possible to recognise the relevance of a correct meteomarine forecast to allow safe navigation and, at the same time, reduce the unnecessary environmental impacts. Bressani (1999) has already demonstrated that on medium-small sailing craft, characterised by ballast water of about 750–1500 1 of capacity, the water quantity to load, subject to the meteorological conditions, is a key point in the boat performance. In fact this operation leads to change in the draught with evident effects on the metecentric height and, thus, on the general both stability and trim.
