A ship is a navigable object, longer than 15 meters, or authorized to carry more than 12 passengers. Types of vessels include passenger, cargo, technical vessels, fishing, public or scientific research vessels. Enrollment in the register of ships is based on the decision of the competent harbor master's office. As of January 1. 2020., there is only a Single Register of Ships. According to the Maritime Code, ship registrations are divided into: first entry in the ship register, entry in sheet A, registration, pre-registration, note, transfer of ship registration, deletion of the ship and re- registration of the ship. If the ship meets the legal requirements and technical standards of the Croatian Ship Register, it is capable of sailing within certain navigation limits and for a certain purpose. Ship's documents and books contain information about important events and actions carried out on board, they must be on board and be available at all times for verification purposes at the request of the competent authorities. Shipping documents are divided into two groups: shipping documents on the identity of the ship and shipping documents on the ship's seaworthiness. The paper presents the concept od division and the importance of ship registers.