• 2018 February 16 09:39

    New DNV GL class notations aim to improve stern tube bearing performance

    DNV GL has revised its class rules for single stern tube bearing installations and introduced two new class notations, “Shaft align(1)” and “Shaft align(2)”, to help customers better manage the risk of stern tube bearing failure. The new class notations can be assigned to both newbuilds and vessels in service in conjunction with propeller shaft withdrawal, DNV GL said in its press release.

    The classification rules covering shaft alignment are formulated to achieve an acceptable distribution of loading on the shaft bearings and lubrication of the aft bearing, taking into consideration the bending moment induced by the propeller during operation. However, during turning manoeuvers at higher ship speeds, exaggerated propeller bending moments can occur, potentially resulting in a reduced shaft-bearing contact area and an exponential increase in local pressure and thermal loading. This could cause damage to the aft bearing. Most of the reported bearing damages have been observed in the aft-most part of the aft bearing, typically during a starboard turn on a right-handed propeller installation. The new rules put additional focus on the impact of these transient hydrodynamic propeller forces and moments, induced in turning conditions, on the aft-most propeller shaft bearing.

    In the “Shaft align” class notations and the revised main class requirements for single stern tube bearing installations, a multi-sloped bearing design is mandatory. This is further supplemented by an additional evaluation of the aft bearing lubrication condition considering an increased propeller-induced hydrodynamic bending moment on the aft bearing in the downward direction. Additional design and installation criteria also assist to increase the operating margins and enhance bearing performance and fatigue lifetime in normal continuous running conditions.

    The notation “Shaft align(1)” is intended for propulsion systems installed on vessels with conventional hull forms and incorporates enhanced aft bearing performance during normal and turning operating conditions. “Shaft align(2)” is intended for propulsion systems requiring additional calculations to predict hydrodynamic propeller loads during turning conditions, for example vessels with non-conventional hull forms such as asymmetric stern, twin skeg etc. Design and in-service follow-up rules for the class notations are included in the updated DNV GL rules for the classification of ships, Pt.6 Ch.2 Sec 10 and Pt.7 Ch.1 Sec 6(38) respectively.

    About DNV GL
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2018 December 16

16:09 Navios Acquisition completes acquisition of Navios Midstream
15:23 Thun Tankers names environmentally adapted tanker Thun Evolve
13:21 Traxens trials IoT network in port environment for first time, at MSC Terminal Valencia
12:32 Executives must watch both sea and air amid trade war tensions, warns Xeneta
10:55 CMA CGM announces FAK rates from ISC to North Europe and the Mediterranean
10:11 PGNiG receives third spot delivery of US-sourced LNG at Świnoujście

2018 December 15

16:23 MOL Passenger Line receives award for outstanding performance in 'Cruise of the Year 2018'
14:53 CMA CGM to implement GRR for India East Coast-West Africa trade
13:51 CMA CGM announces LSS on services from / to China, Hong Kong and Taiwan
12:44 NYK Cruises receives Grand Prix Award for 2018 World Cruise
11:27 TT-Line places order for RoPax "green" ferry with China's Jiangsu Jinling Shipyard

2018 December 14

18:17 Hapag-Lloyd to increase rates from East Asia to Mexico, Central America, West Coast of South America, Caribbean & Panama
17:48 Petersburg Oil Terminal puts into operation its emergency response team
17:33 Vinalines to open container shipping centre next week
17:30 Fairway adjustment will simplify Elbe traffic control already next year
17:27 Final cruise ship for the year calls to the Port of Gothenburg
17:23 The MV Magda joins the Klaveness Bulkhandling pool
17:16 India’s containerised export up 10% in the third quarter of 2018
17:13 FSL Trust announces newbuilding agreement for the construction of two LR2 product tankers
17:13 Havyard project with Havila Kystruten on hydrogen-powered coastal route operations to receive over NOK 100 million in funding from Pilot-E
16:24 World Fuel Services expands bunker operations in US leading up to 2020
15:57 IMO held training workshops in Cameroon Single Window for Foreign Trade Transactions
14:49 Onezhsky Shipyard lays down self-propelled hopper barge of Project HB600
14:08 Irish Continental Group plc takes delivery of cruise ferry W.B.Yeats
13:55 WMU takes part in Ocean Literacy Conference
13:31 First in industry ADNOC co-loads LPG and propylene onto same vessel in Ruwais
13:10 WMU hosted round table discussion regarding key challenges facing IMO
12:53 Bunker market at the Port of Saint-Petersburg, Russia shows mixed price movements (graph)
12:32 Nordic American Offshore secures contract for its PSV NAO Viking
12:11 Rosrybolovstvo supports 2nd Dredging and Hydraulic Engineering Structures Congress
11:50 Association of Commercial Sea Ports celebrates its 30th anniversary
11:24 Gazprom and Itochu sign MoU under Baltic LNG project
11:06 Scorpio Bulkers announces time charter-out agreement
10:48 Domestic ferry safety exercise conducted in Indonesia
10:25 IMO holds training for managing insecurity in west Indian Ocean and Gulf of Aden
10:06 EC adds six new yards to its ‘European List of ship recycling facilities’
09:47 Brent Crude futures price down 0.61% to $61.05, Light Sweet Crude – down 0.4% to $52.37
09:25 GTT notified by HSHI for the tank design of two new LNG carriers for CMM
09:18 Baltic Dry Index is up to 1,365 points
08:06 Fincantieri publishes its Sustainability Plan 2018-2022
07:14 Port of Long Beach cargo volume up to 621,835 TEU in November 2018
06:09 Mitsubishi Shipbuilding holds christening ceremony for LPG carrier "LAUREL PRIME"

2018 December 13

18:43 Coal exports via Rosterminalugol hit 19-millionth tonne mark
18:28 Port of Kaliningrad throughput in Jan-Nov rose 4% to nearly 13 million tonnes
18:25 Tideway completes installation of longest AC offshore wind export cable at Hornsea One in the UK
17:49 Hapag-Lloyd to cancel calls at Port of Bremerhaven
17:25 Building of Johan Sverdrup Phase II begins
17:19 Port of Vyborg 11-month cargo volumes soar 24% to 1.72 million tonnes
17:13 Seabridge first in Belgium to receive the SCA certificate
17:08 Jan De Nul cleans up polluted beaches along the coast in southern France
17:07 Bunker fuel prices at Far Eastern ports close the week lower
17:00 Murmansk Region will improve water safety regulations – Marina Kovtun
16:47 Port of Vysotsk cargo volume in Jan-Nov rises 6% to 16.86 million tonnes
16:36 Maersk Broker Bulk Chartering and NAODAN Chartering
16:30 Murmansk Region Governor is a member of revised State Commission for Arctic Development Issues
16:26 YILPORT Holding wins Port Operator Award at Lloyd’s List Global Awards
16:03 Rosmorport releases RFPs for design of an DF 12/14MW icebreaker
15:49 Jotun and Kansai Paint build relationship to meet marine and protective demand
15:46 Baltic Sea Ports Authority icebreakers assist merchant vessels in the Gulf of Finland
15:21 Containerships receives its first LNG-powered container vessel