The Jensen Maritime-designed Earl W. Redd, the first tractor tugboat in America to enter service in compliance with the US Environmental Protection Agency (EPA)’s Tier IV environmental standards by use of a Selective Catalytic Reduction (SCR) system, was christened in February 2017 by owner Harley Marine Services Inc, of Seattle.

An SCR system scrubs emissions by converting nitrogen oxide (NOx) into ammonia, which is then absorbed by ceramic bricks built into the engines.

The technology significantly reduces the amount of NOx, particulate matter and hydrocarbons released into the environment, and makes the 120ft vessel one of the cleanest-running tugboats in terms of marine emissions.

Built at Diversified Marine Inc.’s shipyard in Portland, Ore., the Earl W. Redd is the first of seven such tugs in development by Jensen.

“With six more Tier IV tugboat designs slated for release soon, Jensen is leading the industry in the production of environmentally friendly designs balanced with high-quality performance,” said Jensen’s Johan Sperling, vice president. “The completion of this tug is a continuation of our commitment to meet the industry’s demands for strong, yet nimble, vessels with quality design.”

Jensen also equipped Earl W. Redd with modern Rolls-Royce US 255-P30-FP Z-drive propulsion and two Caterpillar 3516E diesel engines, for a rated 5,000 horsepower. Two, 125 kilowatt-hour (kW) John Deere generator sets provide the tug’s electrical power.