05.10.2012
Text: Press service of the Krylov Scientific Center
Photo: Model tests of the new icebreaker in flat ice. Press service of the Krylov Scientific Center
Project of a multi-hulled icebreaker capable to make wide ice lanes was presented to participants of the port development conference under the TRANSTEC-2012 international transport exhibition.
According to the head of 54-th laboratory at the Krylov Scientific Center Kirill Sazonov, one of the main objectives affecting development of hydrocarbon production at Russia's freezing sea shelf is foundation of a sea transport system.
Cost estimates show that such system can be effective only with the use of supertankers. However, present-day icebreakers are not capable to escort such ships reliably and safely because of smaller hull beam. Many ice-technology experts work actively on development of various technical facilities making wide ice lane.
The Krylov Scientific Center thoroughly analyzed offers of Finnish experts to design an asymmetric icebreaker and an icebreaker with outriggers. However, according to Kirill Sazonov, these solutions can not settle the problem. Due to nonlinear dependence of ice resistance on hull width, use of an asymmetric icebreaker leads to considerable growth of consumed power. An icebreaker with outriggers also undergoes increased ice resistance because of constraint motion of ice between the icebreaker's hull and outriggers.
Finally, it was decided to design a technical facility making wide ice lane (over 50 meters) in ice cover. This vessel was supposed to have appropriate ice resistance comparable to currently serviceable icebreakers. Otherwise, ice escort by two icebreakers would be more cost-effective than the use of the newly-developed vessel.
As a result of researches, several new projects were offered. One of them was four-(three) hulled icebreaker. It constitutes three or four icebreaking hulls put together. Specific feature is that the hulls are relatively small; each is comparable to a medium- or small-size icebreaker. Every hull is powered with propulsion unit. Right and leftmost hulls can be equipped with rudder propellers, the rest hulls are driven by common screws.
Mutual alignment of the hulls is noteworthy. It allows not only making a wide ice lane but reduce ice resistance. Side hulls are located at such distance from the central hull that their ice resistance is reduced by somewhat 40%. Besides, clearances between hulls are designed in a manner letting small ice pieces easily pass.
Model tests of the new icebreaker included towing tests in compacted flat ice (0.9-, 1.5-, and 2.1-meter thick) and in ridged ice.
As a result, scientists obtained dependency of ice resistance on motion speed in uniformly thick flat ice. That data was used to calculate maximum ice trafficability of the icebreaker; it is maximal ice thickness being overcome by a ship at minimal steady speed of 1.5-2 knots and full power.
Width of the ice lane made by a model of the new icebreaker was measured during the tests as well. It was 54-57 meters in equivalent to full-scale conditions.
It is possible to conclude on the basis of the experiments held that experts of the Krylov Scientific Center developed a new prospective ice-breaking system, i.e. multi-hulled icebreaker capable to make over 50 meters wide ice lane in severe ice conditions.
