Harley Marine opens era of Tier 4 tractor tugs in United States


Harley Marine Services of Seattle has taken delivery of Earl W. Redd, the first U.S. tractor tug that meets EPA Tier 4 emissions limits and the first tugboat using a selective catalytic reduction system (SCR) to comply with the stricter federal standards.

The 120-by-35-foot tug is powered by twin Caterpillar 3516 engines each producing 2,675 hp at 1,600 rpm linked with Rolls-Royce US 255-P30 FP z-drives. Each engine is paired with a urea-based SCR aftertreatment system installed above the engine compartment that converts nitrogen oxide in diesel exhaust to nitrogen and water vapor. The system is expected to exceed federal emissions requirements.

The versatile Earl W. Redd has a Markey hawser winch on the bow and Markey towing winch on the stern to accomplish a wide range of services, including salvage and rescue towing. However, with a bollard pull of 75 tons, the vessel is also suited for docking and ship-assist jobs.

Other components on the tug include twin John Deere 125-kW generators and Schuyler rubber fendering. Earl W. Redd has an oversized 127,000-gallon fuel tank to allow for long voyages, and an 8,200-gallon urea tank.

Jensen Maritime Consultants of Seattle provided plans for the tugboat, which was built by Diversified Marine of Portland, Ore., at its shipyard along the Columbia River. The tug is named for shipyard owner Kurt Redd’s father, who was a longtime presence at the yard.

By Professional Mariner Staff