Dive boat
A dive boat is a boat that recreational divers or professional scuba divers use to reach a dive site which they could not conveniently reach by swimming from the shore. Dive boats may be propelled by wind or muscle power, but are usually powered by internal combustion engines. Some features, like convenient access from the water, are common to all dive boats, while others depend on the specific application or region where they are used. The vessel may be extensively modified to make it fit for purpose, or may be used without much adaptation if it is already usable.
Dive boats may simply transport divers and their equipment to and from the dive site for a single dive, or may provide longer term support and shelter for day trips or periods of several consecutive days. Deployment of divers may be while moored, at anchor, or under way,. There are a range of specialised procedures for boat diving, which include water entry and exit, avoiding injury by the dive boat, and keeping the dive boat crew aware of the location of the divers in the water.
There are also procedures used by the boat crew, to avoid injuring the divers in the water, keeping track of where they are during a dive, recalling the divers in an emergency, and ensuring that none are left behind.
Purpose
The dive boat provides a means of transport to and from dive sites which may be too far or inconvenient for shore access. This is the case with the majority of recreational dive sites. It can also provide a base of operations where the divers can shelter, rest, store and change gear, socialise with other divers, eat and sleep between dives. They can provide enhanced safety, comfort and convenience, and provide guided access to sites of particular interest, but introduce their own set of hazards. They can also provide access to diving procedures which may be difficult, dangerous or impossible from the shore.Types of dive boat
The usual classification of recreational dive boats based on operational parameters includes:- basic dive boats
- day boats
- liveaboards
Dive boats may be privately owned and operated, or run as a commercial business.
The structure, layout and size of a dive boat for any given application may vary considerably according to regional requirements and traditions, and convenience.
Basic dive boats
These are usually open boats 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 private use, 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 first aid oxygen administration equipment.Space in the boat is limited, and divers generally travel and kit up while sitting on the tubes opposite a central cylinder rack where the fully rigged scuba sets are stowed. Water entry is commonly by simultaneous rolling backwards over the side, and return to the boat by climbing back in over the tubes one at a time after removing the heavy parts of the diving equipment and handing it up to the crew. Some boats have ladders which hook over the tubes to make boarding easier for the less athletic diver, others rely on assistance from the crew. 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 and if the boat is filled with water during surf transit maneuvers. These boats are usually fairly fast, maneuverable, seaworthy in surf and rough conditions, and relatively wet and uncomfortable. They seldom provide any shelter from the elements, and their advantages are that they get the diver to the site and back fairly quickly, are generally good for operation through surf, are usually trailerable and can be launched at slipways and beaches.
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 light aluminium "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. Kayaks and canoes are occasionally used as dive boats for one or two divers, and are portable and paddled by the occupants.Decked rigid hulled boats
Flush decked boats with transom boarding arrangements are commonly used in areas with generally pleasant weather and sea conditions. The flush deck with seating and storage along the sides leaves the centre of the deck open for movement to and from the stern. Gates in the handrails amidships may be provided to get divers into the water more quickly, and an awning may be provided for protection from the sun.Inflatable boats
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, folded, and transported in a car or utility vehicle.Day boat
These boats are usually made of rigid materials - such as glass reinforced resin, plywood or aluminium. Day boats are generally relatively large: typically, between 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 "liveaboard" 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 and a small kitchen, 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 during the same day, or multiple dives at the same site, with surface rest and refreshment periods between them.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.
Liveaboard
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 mechanical lift platform. Divers may also transfer to and from the dive site in a tender which is carried on, and launched from, the liveaboard boat.
Liveaboards used on the West Coast of Thailand and in the Red Sea tend to be up to long and have:
- The engine and stores compartments.
- The lower deck, which is mostly cabins for the passengers, usually two passengers per cabin.
- At the stern, a diving platform with diving ladders.
- The main deck, with dining/social room, crew cabins, the bridge, and open space for preparation and storage of dive gear.
- One or two superstructure decks.
Diving support vessels
A diving support vessel is a ship that is used as a floating base for professional diving projects. They are not generally classified as dive boats but share the basic purpose of transporting divers and giving them access to the water at the dive site. Basic requirements are the ability to keep station accurately and reliably throughout a diving operation, often in close proximity to drilling or production platforms, for positioning to degrade slowly enough in deteriorating conditions to recover divers without excessive risk, and to carry the necessary support equipment for the mode of diving to be used.Recent offshore diving support vessels tend to be dynamically positioned and often have additional functions. DP makes a wider range of operations possible, but the platform presents some inherent hazards, particularly the thrusters, making launch and recovery by diving bell widespread. DSVs for inshore operations tend to be much smaller, and may operate while moored for shallow work. Live-boat operations are considered unacceptably hazardous for surface supplied diving unless a stage or bell is used to keep the divers' umbilicals clear of the vessel's thrusters.