Belos is a third-generation "Diving Support Vessel", a modern vessel built in 1985 for conducting advanced underwater operations in the world's offshore oilfields.

FMV - the Swedish Defence Materiel Administration - procured the vessel in 1992 for the Swedish naval forces for use in diving and submarine rescue.

The vessel is intended to serve as a command platform for submarine rescue and to be able to carry and launch URF. With the recently made modification she can carry and launch the british rescuevehicle LR 5.

The vessel is equipped with a dynamic positioning system enabling it to remain stationary over a point on the sea bed even in very heavy weather without anchoring. If required, however, the vessel can four-point anchor at depths down to 500 metres.

The vessel ships a large pressure chamber system which can accommodate divers for several weeks in connection with diving operations. The chamber can also be used for medical treatment e.g. in the case of severe fire in which persons injured by smoke need above-atmospheric-pressure oxygen treatment. Other possibilities include treatment of intractable wounds and pressure chamber treatment following diving accidents.

The vessel is also equipped with a powerful crane for lifts of up to 100 tonnes at depths down to 450 m. The crane can be used for fairly large lifts, e.g. when laying cables or heavy material. One example was the bow visor from the foundered M/S Estonia.

The diving system permits diving operations during saturation diving down to a depth of 450m. Our (limited) experience and diving tables have been developed down to 300 m. In the present North Sea offshore environment, human diving normally applies down to a maximum of 150-180 m. Deeper dives are often accomplished with technical support systems (unmanned vehicles). To assist diving operations there are a "Seaowl" and a "Mantis" system. These permit unmanned operations down to about 300 m and 800 m respectively.

The vessel can also support other types of human diving. Air diving (Hardhat and welter systems) is normally limited to 50 m regardless of system. Deeper dives are carried out with diving bells and Heliox. The heavy diving system permits work at depths down to 60 m for submarine rescue. Light diving is limited to 40 m. The different systems are intended to supplement each other.

Belos is also equipped for fire-fighting. She has water cannon with a capacity of 7200 m³/h. These are for use on serious fires in e.g. an oil terminal, a vessel in dry dock (cf. M/S Sally Albatross at Finnboda Yard) or in ship fires at sea. Oil fields of a certain size and type require the availability of a "fire-fighting ship" during production. Belos has the capacity for this.

The vessel has a helicopter landing pad, upon which any of the country's helicopter types can land. In combination with the large accommodation capacity, the landing pad could be used to advantage as a transit station in the medical care chain in a sizeable rescue operation, e.g. a ferry fire.

The existing medical care resources do not at present permit disaster medical care on any large scale, but they can easily be expanded to a large capacity. The vessel can if required accommodate medical teams and other medical care personnel.

An active high-frequency sonar will shortly be available to permit searches for objects of different sizes on the seabed.

HMS Belos basic data: