Page 45: of Maritime Reporter Magazine (May 2021)

TECH FILE SUSTAINABLE PROPULSION

Photo left:

The test tank at

KONGSBERG’s Hydro- dynamic Research

Center.

Photo below: ntegrating the pro- peller and rudder in the Promas unit has reduced drag and boosted ef? ciency.

Photo on opposite page:

A central CPP and pair of rotatable Azipull mechanical thrusters give the Finnish Coast Guard vessel Turva ef? cient operation and optimal manoeuvrability. tinuously, smoothing out the engine dard twin-screw con? guration. When “We have estimated that this combina- load and enabling power-generating ca- the vessel is carrying out low-speed as- tion will reduce power consumption by pacity to be reduced by up to 30%. The signments of this nature, the CPP can be up to 15% when benchmarked against positive rami? cations for sustainability feathered to reduce drag. the twin-screw norm,” said Grunditz. are considerable, with the potential for “If Turva is operating in frozen con- “That’s an annual saving in the region of vessels to carry out zero-emissions op- ditions,” he saidd, “the thrusters can be $1.8 million. The Promas systems will erations for a given period of time, or to used to ? ush ice around the hull while allow RoPax ferries to spend shorter run solely on battery power in environ- the CPP works to power the vessel times in ports and harbors, meaning that mentally sensitive locations. With their through the ice. During high-speed tran- lower speeds are required when in tran- double barrier seals, the pods are VGP sits, the CPP shares loading between the sit. This marked overall improvement (Vessel General Permit) compliant, even three propellers while steering is han- in energy ef? ciency is obviously kinder without the use of EAL (Environmental- dled by the thrusters. This arrangement to the environment, allied to the fact ly Acceptable Lubricants). boosts performance and reduces fuel that the reduction in propeller loading

Grunditz looks at the Finnish Coast consumption; which, in turn, decreases signi? cantly cuts down on underwater

Guard vessel Turva, equipped with a the boat’s carbon footprint.” noise which has been shown to have a central CPP (controllable pitch propel- potentially negative effect upon marine ler) and a pair of rotatable Azipull me- The Triple-Screw Alternative mammals.” chanical thrusters, as a strong reference For RoPax, Kongsberg Maritime also These bene? ts are echoed in another for the Kongsber cumulative brand. offers a more sustainable, triple-screw con? guration which combines a central “Turva needs to be highly maneuverable alternative to the twin-screw con? gura- controllable pitch propeller in front of when undertaking tasks including ice tion which large ferries have traditional- an azimuthing thruster with a counter- breaking, dynamic positioning and tow- ly deployed. In the triple-screw arrange- rotating propeller. This arrangement, ing, and for this the rotatable thrusters ment, a large-diameter, lightly loaded designed to regain energy and rotational have been found to deliver substantially central propeller works in tandem with losses, results in ef? ciency gains of be- better positioning accuracy and mobility two open-shaft Promas propulsion and tween 10 and 15% over conventional than would be achievable with a stan- maneuvering systems. twin-screw systems.

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MR #5 (34-49).indd 45 5/6/2021 5:02:59 PM