Russian Maritime Register of Shipping (RS) has developed and implemented requirements to hull ice strengthening structures of double-acting ships.
The ships that comply with the new requirements at the shipowner's discretion may be assigned the distinguishing mark DAS ( ) to the character of classification, where the RS ice class for stern-first operation is indicated in brackets. The requirements have been integrated into Part XVII of the Rules for the Classification and Construction of Sea-Going Ships as a new section.
The provisions of the new section are based upon R&D on hull ice strengthening structures of ships operating stern-first as well as upon RS hands-on experience received during plan approval of double-acting ships.
The new DAS distinguishing mark requirements cover:
· aft end design, in way of skegs and azimuth thrusters;
· new approximate dependencies for shape functions;
· determination of ice loads on the aft region.
The requirements have been introduced into RS Rules by Circular № 314-47-1265C of 17.09.2019
By the end of 2019 RS is to complete the development of the relevant requirements for machinery, propulsion and navigation equipment.
The DAS concept foresees the optimisation of a ship’s hull form for efficient movement both in clear and ice-covered water. The DAS concept implementation became possible after the development of new AZIPOD azimuth thrusters. Already 40 double-acting ships of higher ice classes Arc6, Arc7 and Icebreaker6 are built to RS class.
RS is the globally recognised leader in the development of the requirements for ice class ships. The RS-classed fleet comprises 3000 ice class ships including more than 40 icebreakers. Over 500 RS-classed ships are Arc4 and higher.