Tuesday, May 17, 2016

Jensen Designs High Performance Tractor Tug

By Mark Edward Nero

Seattle-based naval architecture and marine engineering firm Jensen Maritime has designed a new high performance tractor tug for Vessel Chartering that features some of the first Tier IV engines meeting higher federal air emissions standards among US tugboats.

The multipurpose tractor tug, which is being built by JT Marine of Vancouver, Washington, was jointly developed by San Francisco-based Vessel Chartering and Jensen, a subsidiary of Crowley Maritime, Crowley said May 4.

The 110-foot long vessel is designed to have the ship assist and escort capabilities of smaller harbor tugs, while featuring the improved towing performance and increased range of larger ocean-going tugs. Also, the escort capability was enhanced to provide support for assisting large, 18,000-TEU containerships due to an increased future demand in West Coast ports. The design offers the flexibility to support ship escorts, assists and towing.

The engines are designed to meet the federal Tier IV standard, which incorporate the emissions-reducing performance requirements by the US Environmental Protection Agency. To meet the requirements, the two engines on this vessel use systems that clean exhaust gases after they have left the engines. This is the third tugboat designed by Jensen Maritime with engines meeting the Tier IV requirement.

The tug was also designed without any ballast tanks, thereby eliminating the need for ballast water discharge and the potential transfer of invasive species. Instead of ballast tanks, the tug will transfer fuel, as necessary, in order to maintain proper trim.

The 40-foot wide vessel is to be powered by a pair of 3,385-horsepower Caterpillar 3516 Tier IV engines. With an electrically powered, double drum tow winch aft by Rapp USA and an electrically powered hawser winch forward by Markey Machinery as deck machinery, the vessel will be capable of a 93-to-95 short-ton bollard pull. Both winches’ electrical power will remove any chance of a hydraulic oil spill on deck.

The tug is designed to carry up to 123,000 gallons of fuel, 4,300 gallons of fresh water, and up to 4,500 gallons of urea, which is used for treatment of the main engine exhausts in order to meet Tier IV emissions requirements. A water maker is being installed for potable water when out at sea, and a large pilot house will provide all-around visibility. The deckhouse has an open feel with a large mess and lounge area along with accommodations for a 10-person crew.

The tug’s planned for delivery in the second quarter of 2017 to Vessel Chartering, a wholly owned division of San Francisco-based tanker escort and assist company Baydelta Navigation.