Medium ship has 2 lower decks and the large ship can have up to 3 lower decks. Now , if you'd like to have a crew on board, you could. They're like servants in construction but preform different duties. There is a navigator, cook as  RS gold well as a cannon-man (Operates weapons in mini-games - described in a future post) or a repairman to fix your ship. It is your responsibility to pay your crew money and provide them with crew quarters. If you decide to go out on the sea, you are able to also store your supplies, such as alchohal and food items. When you head out into the sea, you won't be attacked by other players ships but you can be stopped and searched by a security vessel.

In order to ensure that you do not transport weapons or persons who are not yours, they can board your vessel. But you can get passengers on board who pay a fee of up to 10k , depending on the size of the boat. Any Runescape port can be reached by. BTW You CANNOT Summon Familiars or any other. Pets are not allowed on the boat of another person or on your vessel. If you depart your ship and  OSRS buy gold do not return the ship, your crew and vessel remain in port. The crew is not able to board your ship. Except if you dismiss the crew, do not pay them, or they are unhappy with the conditions on your vessel (e.g. there isn't enough food, too small sleeping spaces and so on.), nobody can access your vessel.