NAVAL RSV 421: Propulsion and Manoeuvrability

The Bulgarian research/survey vessel Sv. Sv. Kiril i Metodii (NAVAL RSV 421) is on a historic first voyage to Livingston Island to support the 31st Bulgarian Antarctic expedition there.

Originally built as an auxiliary vessel for servicing oil platforms, laying cables and pipe routes and sampling the seabed, Sv. Sv. Kiril I Metodii turned out to be extremely suitable for conversion into a research vessel. One of the reasons for this is the ship's propulsion system with azimuth thrusters, a system of mechanisms that ensures the ship's good propulsion and precise manoeuvrability.

Some ships are propelled solely by internal combustion engines, while NAVAL RSV 421 is an electric ship. It has main diesel generators, three in total. Each of these diesel generators has two mechanisms: an internal combustion engine which is connected to a generator.

"Using the fuel from the internal combustion engines, we convert that energy into torque, which we use to generate electricity through the connected generator. This electricity provides the operation of all the other mechanisms. It is distributed by the Central Control Station according to the needs and operations that the crew has to perform at that moment. The actual control of the propulsion complex comes from the ship's command bridge," NAVAL RSV 421 First Engineer Dimitar Bahchevanov told BTA.

The generators supply power to two azimuth thrusters. This mechanism has the great advantage of allowing the ship to change to any one direction, maintain a set course or position itself at a fixed point without being affected by external weather conditions, including currents and swell, he added.

Along with the azimuth thrusters at the stern, NAVAL RSV 421 also has two bow thrusters - two parallel propellers under the bow with one propeller each.

It is this set of mechanisms and movements that allows NAVAL RSV 421 to move and manoeuvre precisely, even in more severe weather conditions.

The ship uses a dynamic positioning system that provides external information about wind speed and direction, current, swell, etc. Information on these weather conditions comes from various sensors located on the ship.

BTA's Daily News editor Konstantin Karagyozov is the only member of the media who is travelling on board the ship to Livingston Island and back, and will cover the Bulgarian expedition on site throughout the stay in Antarctica.