Icebreaking terminal tugs for SvitzerWijsmuller designed by Robert Allan Ltd.

April 3, 2007

In late February 2007 the high performance ASD terminal/escort tug Svitzer Sakhalin was delivered from ASL Shipyard of Singapore to the Owners, SvitzerWijsmuller of Copenhagen, Denmark. Svitzer Sakhalin is the first of four tugs being built to this new unique design, which will operate under a long term contract to Sakhalin Energy Investment Corporation. The second vessel, Svitzer Aniva is currently on passage to Sakhalin with an estimated time of arrival of late March. Two additional tugs to the same design are currently under construction at the Admiralty Shipyard in St. Petersburg, Russia, with delivery scheduled for late in 2007. The design was developed for SvitzerWijsmuller by Robert Allan Ltd. of Vancouver, BC under the direction of Jim Hyslop as Project Manager.

These heavy-duty ice-class tugs will be used at the Prigorodnoye oil export terminal and Liquefied Natural Gas plant, located near to Korsakov Port, in Aniva Bay on the south coast of Sakhalin Island. The oil terminal and LNG plant, both currently under construction, will handle both crude oil and LNG exports. The tugs will be expected to fulfill duties which include ship berthing, buoy maintenance, ice channel breaking and ice management at the terminal.

The tugs were built to Lloyd’s Register of Shipping requirements for a 100A1 Tug, Fi-Fi 1 with waterspray, LMC, UMS, IWS, Ice Class 1AS FS notation, as well as to the requirements of the Russian Maritime Register of Shipping for an ice class LU-5 notation for the hull only. The vessel also meets all SOLAS and International Loadline requirements.

Particulars of the Svitzer Sakhalin are as follows:

The propulsion system comprises a pair of Bergen Model C25:33L8P diesel engines, each rated 2,395 kW at 1,000 rpm, driving a Rolls-Royce Model US 305CPP Z-drive thruster. This combination delivered a bollard pull of 73 tonnes, and a free running speed in excess of 13.5 knots on recent acceptance trials.

These tugs are outfitted to a high standard for a crew of six persons, plus two Client representatives. The Officer’s cabins include private en suite facilities, and others share a common lavatory/shower facility. There is a spacious lounge/mess area and a fully equipped modern galley.

The main hawser winch is a double drum, hydraulic winch supplied by Rolls-Royce. Both drums have a capacity for 110 metres of 120 mm diameter synthetic hawser. The brake capacity is 180 tonnes. Aft is a single drum towing winch, with a capacity for 800 metres of 52 mm SWR, and with a brake capacity of 180 tonnes. The latter is located in a fully enclosed shelter.

Additional deck equipment includes a large utility/buoy-handling crane by Norcrane, rated 10 tonnes at 8 metres outreach, a 10 tonne tugger winch, shark jaws and tow-pins mounted flush with the main deck aft (first pair of tugs only), ahead of a 4 m long x 1,000 mm OD stern roller. There is also deck space for storage of two 20′ containers.

The tug is equipped to a full Fi-Fi 1 (with waterspray) Classification, with two main-engine driven pumps, with a total capacity of 2,800 m³ per hour.

The ship’s service generators are a pair of Volvo D9 MG gensets, each rated at 225 kW, delivering 400 volts/3 phase/50 Hz power throughout the ship. There is also a 24 kW air-cooled emergency generator.

The new design was developed in response to a very demanding Statement of Requirements, issued to industry for this project. The requirements included the ability to break 85 cm of level ice at a minimum of 3 knots, perform harbour ice management, and when operating in pairs break a channel wide enough for the tankers calling at the terminal. In addition, the tugs had to meet the stipulated minima of 70 tonnes BP and a speed of 12 knots. In order to verify the design, an extensive series of model tests were commissioned by Robert Allan Ltd., carried out at the HSVA, Hamburg, Germany, under the direction of Alan Reynolds of Offshore Research Ltd. of Vancouver, on behalf of the designers. The program focused on the icebreaking performance of the tug, and was conducted as both towed and self-propelled tests. The performance in ice exceeded all expectations, and in particular the ability of the tug to break out of an ice channel was exceptional. Very little ice-propeller interaction was observed.

The unique hull form incorporates an aggressive icebreaking “spoon” bow, with shallow buttock angles in the ice contact zone, optimized for icebreaking performance. This shape merges into a modern ship-docking style bow, providing low contact pressures for tanker handling duties.

Additional design features developed to deal with the harsh winter environment in Sakhalin include underdeck heating and a large boiler/heat recovery system. The underwater hull is treated with Inerta 160 low friction ice-capable coating.

These vessels provided a unique opportunity for the design team to combine their historic expertise in icebreaker design, gathered primarily in vessels built for the Canadian Arctic in the mid 1970’s and through the mid-1980’s, with their capabilities in modern ship-handling tug design.

For more information on these ice-class tugs, or any other high-performance tug design requirements, please contact us.