main deck, which has the dining/social room, crew bedrooms, the bridge, and open space. One or two upper decks. Others Boats intended for other purposes can usually be used as dive platforms provided that there is reasonably convenient access to the water and enough space to carry the necessary equipment. Auxiliary sailing yachts and motor yachts are often used by their owners as dive boats, and catamarans can be particularly amenable to this function as they often have spacious decks and stern boarding facilities with swim ladders. Diving from a boat Procedures for diving from a boat vary depending on the boat, the diving equipment, the dive site and the dive plan. Stowage of dive gear Trim and stability of small boats can be significantly influenced by where and how the dive gear is stowed. When transiting a surf line, or in other rough sea conditions, the movement of the boat can cause poorly secured equipment to move, which can directly injure the occupants, and adversely affect trim and stability, and thereby the safety of the vessel and its occupants. Dedicated dive boats usually provide cylinder racks to stow the scuba sets, and may also provide bins or racks to stow other heavy equipment. Larger vessels, particularly liveaboards, may also provide a camera table and fresh water rinsing facilities for washing gear after the dive. Deployment of divers Divers will usually enter the water with positive buoyancy, as this allows them to make final surface checks, signal to the boat that they are OK and co-ordinate descent with a buddy, but there are occasions when negative buoyancy entries are chosen to avoid excessive drift in a strong current, in which case all pre-dive checks must be done on the boat, the buoyancy compensator, and where applicable, the dry-suit emptied of gas, and the breathing apparatus function thoroughly checked before entering the water. The risk of injury if there is an equipment problem is greater for negative entry, particularly with breathing gas failures. Water entry Several techniques are used for water entry from boats, depending on the layout of the vessel, particularly the freeboard at the entry points. Large dive boats often have a permanent or folding platform at the stern just above the water, intended to make water entry and exit safer and more convenient for divers. Such platforms will usually be provided with steps or ladders from the deck,