Vessels are contracted through public tenders for a period of four years, and the possibility of one renewal for the same time period. For new contracts, there is always a period of time when the vessel is under preparation, and the location of vessels is occasionally revised based on risk assessments and bids received. The number of vessels available at any given time, and the exact location, varies depending on these factors. The latest figures and distribution of EMSA vessels can be accessed in the EMSA website.