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Seeking a complete power and propulsion system designed specifically for tug operations, Seattle-based Harley Marine Services has turned to Hamburg-headquartered Caterpillar Marine - ordering four Cat 3516 marine propulsion engines and four Cat Propulsion Marine Thruster Azimuth - Tug (MTA-T) rated drives.

The ordered units will power two new Harley Marine harbour tug vessels currently under construction at Diversified Marine Inc., a shipyard in Portland, Oregon.

In a statement, Emil Cerdier, sales manager for Cat Propulsion, commented: "Much of Harley Marine's fleet is powered by Cat engines, and with the construction of these two new vessels, they're adding our tug-specific propulsion solution as well. Getting a complete package from one supplier simplifies the design, installation, and service support, allowing Harley to rely on the Cat dealer network as a single point of contact for the entire powertrain system."

Each Harley Marine harbour tug is to include a pair of 3516 engines, each delivering 2575 horsepower (hp) - or 1920 kilowatts (kW) - at 1600 revolutions per minute (rpm) and two MTA 524-T thrusters with a 95.5-inch (2,400-millimetre) propeller diameter.

The MTA 524-T is specifically optimized for the operation profile of a tug. Based on the standard MTA design, the tug rated drives include features to maximize bollard pull, simplify installation and maintenance, and increase manoeuvrability. The Harley Marine units are to be delivered with custom-made fixed-pitch propellers and a PTO-powered steering and lubrication system.

Cat Propulsion's complete package for tugs includes engines, high-speed shafting, clutches, and controls. The display consoles for the control system will also control engine and thruster functionality.

"Our MTA-T units bring the twin advantages of performance excellence and economy to the tug market," Cerdier said. "Customers like Harley Marine will benefit both in terms of bollard pull and from the reliability of a consolidated control-engine-thruster package with component parts optimized to work together."

Cat dealer Peterson Power led the efforts on the project, helping refine the spec and eventually supporting the installation and service of these systems. Cat Financial is providing complete vessel financing throughout the construction and term of both tugs.

The Cat engines and thrusters are expected to deliver in mid-2016, with vessel deliveries in early 2017.

Caterpillar Marine will be at Booth #1901/#2001 at the upcoming International WorkBoat Show in New Orleans on December 1–3.

For further information about the company, please visit www.cat.com/marine.