Article 241 of the French Customs Code
Ships and other seagoing vessels, including maritime drones as defined in article L. 5000-2-2 of the French Transport Code, which have been registered are subject to mortgages, unless they have been registered because they meet the conditions defined in 3° of article L. 5112-1-3 of the French Transport Code. They may only be encumbered by conventional mortgages. To be valid, mortgages must be in writing.