A dive boat is a boat that recreational divers use to reach a diving site which they could not conveniently reach by swimming from the shore. Dive boats may be propelled by wind or muscle, but are usually powered by internal combustion engines.
Dive boat features
Features that make a boat suitable for use by divers are:
- Sufficient space and stability to carry the divers and their equipment
- Facilities for the divers to enter the water from the boat and board the boat from in the water
Safety equipment may be required, either by legislation or the diver certification agency to which the boat operator is affiliated. This will usually include:
- marine VHF radio
- small craft emergency equipment - life jackets, flares, fire extinguishers and other equipment according to the size and operating range of the boat
- oxygen first aid equipment
- diving shot
- a signal flag to indicate that divers are in the water.
On larger boats additional diving support facilities may also be present:
If the freeboard of the boat is too high for the divers to climb back on board unaided, a ladder or other aid must be provided. Boarding aids range in cost, complexity, safety and ease of use, from a rope ladder, through rigid ladders and stairs with handrails, christmas tree ladders which allow the diver to climb while wearing fins, to temporary and fixed stern platforms, lifting platforms and passerelles.
Types of dive boat
Many types of boat can be used as dive boats. Some notable types of dive boat are:
- the open boat
- rigid-hulled inflatable boats (RHIB or RIB)
- open rigid hulled boats
- inflatable boats
- the day boat
- the live-aboard
Open boats are generally used for short distance, or short duration, trips to dive sites, usually for a single dive or sometimes for a "two tank" trip, either with both dives at the same site, or with the second dive on the way back, or a short distance from the first. They generally have no amenities other than seating and stowage for dive gear, and the divers are usually exposed to wind, spray and sun during the trip. It is common for divers to kit up in their dive suits before boarding, for protection from the weather. It is unusual for the operator to provide refreshments other than bottled drinking water and an after-dive candy.
Rigid-hulled inflatable boat
Divers only spend a few hours at a time on these fast but exposed boats. The boats are usually relatively small so they can easily be transported on roads and launched at a convenient site depending on the weather. Boats of this size can be launched from slipways or through the surf on suitable beaches. The smaller models are suitable for amateur divers, as they can only transport a few divers. The larger boats can carry enough divers to be viable for professional use. These boats will generally carry basic safety equipment such as marine VHF radio, small boat safety gear, lifejackets and oxygen first aid.
The divers usually sit on the inflatable tubes and enter the water by rolling backwards over the side, and return to the boat by climbing back in over the tubes after removing the heavy parts of their diving equipment and handing it up. Some boats have ladders which hook over the tubes to make boarding easier for the less athletic diver. An advantage of this type of boat compared with similar-sized rigid boats is that the inflated tubes make the boat very stable during the entry and exit of the divers.
Open rigid hulled boats
These serve a similar function to the Rigid-hulled inflatable boats, but do not have inflatable tubes. They are more durable, but usually heavier for the same load capacity. In Australia and New Zealand the "tinnie" is often used as a dive boat. These boats are usually less stable than the equivalent inflatable and are not as easy to climb back on board, but are light, durable and economical.
These are usually relatively small and used only for short distances with a small number of divers. They are relatively uncomfortable, and not usually very fast, but are stable for their size and can be deflated and transported in a car or utility vehicle.
These boats are usually made of rigid materials - such as glass reinforced resin, plywood or aluminium. Day boats are generally relatively large: typically, between 60 to 90 feet (18 to 27 m) in length, as they must provide some comfort for the passengers for several hours. Many day boats are used for scuba-divers and also for other marine tourism activities such as fishing and whale-watching. In general, divers or passengers will spend only the daylight hours on a day boat, and do not sleep in them overnight. Dive boats which provide sleeping accommodation are generally referred to as "live-aboard" boats. Generally a professional crew operate the boat. The boat provides shelter from the weather and is likely to have various facilities such as a toilet (called the "head") and a small kitchen (called a "galley"), to cater for the guests and crew. Day-boats may have a saloon where divers can relax on upholstered benches, and one or more dining tables. Many day boats also have an uncovered sun-deck, and a shaded area, for divers wishing to be out in the open air. The boat will usually have a diving air compressor, oxygen first aid, a VHF radio, a GPS and possibly gas blending facilities. A day boat would generally be used to transport divers to multiple dive-sites (typically between one and three sites) during the same day.
The divers usually enter the water by stepping off a dive platform or the side of the boat, and return on board using a ladder or a lift. In some cases a smaller "tender" is used to carry divers to and from less accessible sites, and to rescue divers who are in difficulty or who drift away from the boat.
On these commercially operated boats, the divers live and sleep on board and dive from the boat for periods of a few days to several weeks. A professional crew navigate and operate the boat. In addition to the usual domestic facilities expected by hotel guests, the boat will have a diving air compressor and emergency oxygen. Some have gas blending facilities and a few even carry a recompression chamber.
The divers enter the water by stepping off a dive platform or the side of the main deck, and return to the boat using a ladder or a lift.[clarification needed] Divers may also transfer to and from the dive site in a tender which is carried on, and launched from, the live-aboard boat.
- The lowest deck, which is for the engine and stores.
- The lower deck, which is all or mostly cabins for the passengers, usually two passengers per cabin.
- At the stern, a small diving deck with diving ladders.
- The main deck, which has the dining / social room, and crew bedrooms, the bridge, and open space.
- One or two upper decks.
- Gilliam, Bret (1992). "Evaluation of decompression sickness incidence in multi-day repetitive diving for 77,680 sport dives". Journal of the South Pacific Underwater Medicine Society 22 (1). Retrieved 2014-02-10.
Seamanship: A Guide for Divers, BSAC, ISBN 0-9538919-7-6