According to Spanish Law 27/1992, of November 24, on State Ports and the Merchant Navy, it is mandatory to have proof of payment of the insurance premium for the current period on the boat. This document  it will prove its validity, provided that contains at least the following specifications: The insurance company that underwrites the coverage. Sufficient identification of the insured vessel. The coverage period with indication of the date and time when its effects begin and end. The indication that it is the compulsory insurance coverage. This documentation must be on board the boat. If it is required by the competent authorities and said documentation is not found on board, the policyholder will have five business days to justify the validity of the insurance before them. The navigation of leisure boats that are not insured in the established way, will suppose a serious infringement  (Chapter III of Title IV of Law 27/1992, of November 24, on State Ports and Merchant Navy of Spain).