MV Captain Kurbatskiy - Design

Design

The hull form of the ship, a result of intensive model tests in both open water and model ice, was very different from that of conventional merchant vessels, being more akin to polar icebreakers than traditional cargo ships. However, in addition to good icebreaking and manoeuvring capabilities in various ice conditions the vessel had to be able to operate in open water without bottom slamming or shipping of green water occurring in rough seas. Despite the compromises the ship had impressive icebreaking capability — the SA-15 class ships were designed to break level ice up to one metre (3.3 ft) in thickness with a snow layer of 0.2 metre (0.7 ft) in continuous motion without icebreaker assistance. The ships were also the first freighters in ten years to be built to the highest Soviet ice class notation available for merchant ships, ULA.

The ship had a maximum overall length of 177.20 metres (581.36 ft) or 173.55 metres (569.39 ft) with the stern notch excluded. The breadth of the ship, like all other cargo ships operating in the Northern Sea Route, was limited to 24.50 metres (80.38 ft) by the size of the escorting icebreakers. The shallow waters of the Northern Sea Route limited the draught to 9 metres (29.53 ft), but outside the arctic the cargo capacity of the ship could be increased by allowing the ice-strengthened parts of the hull to become submerged.

The harsh operating conditions of the arctic seas placed high requirements on the strength, reliability and redundancy of the propulsion machinery, especially for single-screw ships operating independently without icebreaker escort. For this reason the robust propulsion system had several innovative features and prototype arrangements to improve the ship's operational capability. Propulsion power was provided by two 14-cylinder Wärtsilä-Sulzer 14ZV40/48 4-stroke medium-speed diesel engines running on heavy fuel oil, each with a maximum continuous output of 7,700 kW (10,326 hp) at 560 rpm. As a precaution against failure of the propeller pitch control mechanism the main engines were directly reversible. The main engines were connected to a single propeller shaft through a double input/single output single-stage reduction gear equipped with separate multi disc clutches and Voith fluid couplings. The hydrodynamic couplings that allowed over 100% slipping between input and output shafts were used in difficult ice conditions to increase propeller torque and protect the main engines from large torque variations resulting from propeller blades hitting the ice. The fully locking mechanical clutches were used to improve fuel efficiency when the ship was operating in open water or light ice conditions. Because the power output per shaft of the SA-15 class freighters was at that time one of the highest among icebreaking ships, second only to the Arktika class nuclear icebreakers, the propeller of the ship was of extremely robust design. The four-bladed stainless steel controllable pitch propeller was developed and manufactured by KaMeWa specially for the SA-15 project.

A multipurpose general cargo ship, the vessel was capable of carrying a wide variety of cargo ranging from general and dry bulk cargoes to containers, heavy cargo, long goods and trailers. The ship had five holds fitted with tweendecks, four forwards and one abaft of the superstructure. The ship, designed to serve the remote arctic regions, was also equipped with flexible winterized cargo handling equipment for loading and unloading in undeveloped ports. For loading and unloading of general cargo, containers and bulk cargo the ship was geared with four deck cranes located on the centerline, one on the aft deck and three forwards of the superstructure. On the continuous tweendeck the ship could also carry roll-on/roll-off cargo which was loaded and unloaded via a stern quarter ramp that could also be lowered directly on ice.