The first two Z-Tech 2400-class harbour tugs were built at the Leevac Shipyards Jennings. Image courtesy of Leevac Shipyards, LLC.
Chole K was delivered to Bay-Houston Towing Company in September 2013. Image courtesy of Robert Allan Ltd.
Zeus was delivered to its owner Suderman & Young Towing Company in October 2013. Image courtesy of Robert Allan Ltd.

Z-Tech 2400-class tug

The new Z-Tech 2400-class terminal and escort tugs, which have been designed and engineered by Canadian naval architects and marine engineering company Robert Allan (RAL), have been designed particularly to operate in major ports and marine terminals.

Zeus and Chole K, the first two tug boats of the Z-Tech 2400-class, were ordered in April 2012. The two vessels were built at Leevac Shipyards Jennings, for Suderman & Young Towing Company and Bay-Houston Towing Company respectively.

Chloe K was delivered in October 2013 and her sister vessel Zeus was delivered in December 2013. G&H Towing Company will operate the vessels in the Ports of Houston and Galveston on behalf of the owners.

Suderman & Young Towing Company and Bay Houston Towing Company again signed contracts with Eastern Shipbuilding Group (ESG) in August 2014, for four RAL-designed Z-Tech 2400 harbour tug boats.

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Z-Tech 2400-class terminal and escort tug boat design

The Z-Tech 2400 harbour tug is based on the Z-Tech concept, which was originally developed to meet the PSA Marine of Singapore’s requirements. The vessel features a rounded stern and a proven underwater hull design.

The tug offers omni-directional performance and its wheelhouse is well designed to clear the ship’s sides during escort missions. The vessel has an overall length of 80m, beam of 38.3m, depth of 15.9m and maximum draft of 16m.

The tug boats are built as per US Coast Guard (USCG) regulations for vessels under 200 US GRT and are assigned the ABS class notation A1 Towing Vessel, AMS Escort Service and ABS Loadline Statement of Compliance (SoC). The owners of the vessels have also opted to comply with the International Convention on Load Lines (ICLL) regulations.

The vessels have been outfitted to provide accommodation to six people. Each vessel features a main deckhouse containing a galley, mess, and two officer cabins with a shared washroom. The tug boat also features two double berth cabins, storage space and a common washroom in the lower deck.

The wheelhouse is fitted with a single split-control station enhancing the visibility for both ahead and aft operation, as well as over the aft working deck.

The vessel is equipped with tanks that can store 37,600 gallons of fuel oil; 6,200 gallons of potable water; and 2,900 gallons of sewage.

The new tug boat and terminal vessel’s propulsion

The Z-Tech 2400-class vessels are fitted with a marine propulsion system comprised of two Caterpillar 3516C Tier-3 high power main diesel engines. Each engine driving a Schottel Rudderpropeller (SRP) 1215 in nozzles Z-drive develops a maximum power of 2,575hp at 1,600rpm.

"The propulsion system integrates two John Deere 4045AFM85 Tier-3 main generator engines, which generate a power of 99kW each."

The propulsion system also integrates two John Deere 4045AFM85 Tier-3 main generator engines, which generate a power of 99kW each at 1,800rpm.

The Z-Tech 2400-class vessels are fitted with a Markey DEPCF-48S forward hawser winch with a 36in wide drum. The electrically driven winch has a mid-drum brake with a holding capacity of approximately 300,000lb and a line pull of 16,000lb at 83ft/min. The aft deck has a towing bitt with a safe working load (SWL) of 60t.

An upper row of cylindrical fenders with 36in diameters are fitted at the bow as well as a lower course of Schuyler SR3D-2 double loop soft fenders of 16in diameters. The sheer fendering incorporates a Schuyler double loop soft fender.

The propulsion system gives the vessel an average speed of 12.3k and a bollard pull of 61.1t.