The SA-15s feature several innovative systems for icebreaking freighters. The ship is directly driven by diesel engines through reduction gears, being equipped with controllable-pitch propellers (CPP). As described above, CPPs are a useful design for icebreaking ships, as they provide rapid power supply and quick response for switching between full ahead and astern, in particular in ramming mode. Also, both friction and fluid couplings are installed between the main engines and the reduction gear. The former is employed when navigating in ice to protect the propulsion system from ice torque, and the latter is used in open water or light ice conditions to improve fuel efficiency. (Figure 4.1-5 (a)). Another innovative feature of the SA-15, an air-bubbling system, is fitted to reduce friction and accretion between the hull and snow or ice at anchor in the winter. The bow also incorporates an observation deck for monitoring of ice conditions. The deck is linked to the accommodation space by a narrow, sheathed corridor, so that the crew can check conditions without venturing out to the exposed sections of the ship.
(2) Icebreakers
In addition to the SA-15 freighters, built for polar-sea shipping, the Soviets constructed a powerful fleet of icebreakers to support these vessels in NSR waters. These NSR icebreaker support operations are today divided east and west between two organizations, the Far East Shipping Company (FESCO), headquartered in Vladivostok, and the Murmansk Shipping Company (MSC) (Table 4.1-4). The icebreakers in question belong to the Russian government, which lends the vessels to the two shipping firms under an operating contract (WP-96). Currently FESCO's icebreakers suffer from a low availability rate, so in practice only MSC is operating Russia's icebreaker fleet.
The core of the Russian icebreaker fleet consists of five Arktika-class nuclear icebreakers (the Arktika, Sibir, Rossiya, Sovetskiy Soyuz and Yamal), all of which were constructed during the Soviet era. Represented by the Arktika-class icebreakers, with 75,000HP propulsion systems and the ability to perform continuous breaking of ice 2.3m thick, Russia boasts the most powerful icebreaker fleet in the world. In addition, two shallow-draft icebreakers designed for coastal and river operation, the Taymyr and Vaygach, were jointly developed by Finland and Russia. Both of these nuclear-powered icebreakers are presently operated by MSC. Russia's diesel-electric icebreakers, on the other hand, were constructed in Finland and are allotted to MSC and FESCO. As described in the following section, most of Russia's icebreaker fleet uses the conventional, wedge-type bow design, despite the recent development and commercialization of an improved bow shape that has demonstrated excellent icebreaking performance.
