Article 9
Seasonal and short-time period operations 1. If a shipping company operating a regular service on a year-round basis wishes to introduce additional ro-ro passenger ships to operate for a shorter period on that service, it shall notify the competent authority of the host State or States not later than one month before the said ships are operated on that service. However, in cases where, following unforeseen circumstances, a replacement ro-ro passenger ship must be introduced rapidly to ensure continuity of service, Directive 1999/35/EC shall apply. 2. If a shipping company wishes to operate seasonally a regular service for a shorter time period not exceeding six months a year, it shall notify the competent authority of the host State or States not later than three months before such operation takes place. 3. Where such operations take place under conditions of lower significant wave height than those established for the same sea area for all-year-round operation, the significant wave height value applicable for this shorter time period may be used by the competent authority for determining the height of water on the deck when applying the specific stability requirements contained in Annex I. The value of the significant wave height applicable for this shorter time period shall be agreed between the Member States or, wherever applicable and possible, between Member States and third countries at both ends of the route. 4. Following agreement of the competent authority of the host State or States for operations within the meaning of paragraphs 1 and 2, the ro-ro passenger ship which undertakes such operations shall be required to carry a certificate confirming compliance with the provisions of this Directive, as provided for in Article 8(1).