The last of five large tractor tugboats built by Nichols Brothers Boat Builders of Freeland is undergoing sea trials at the Langley Marina.

Its new owner, Baydelta Maritime of San Francisco, is expected take delivery in Langley by the end of the month, Matt Nichols, managing director for business development, said Monday.

The tug was launched Aug. 12, complete with a christening from Sharon Hart, executive director of the Island County Economic Development Council.

The latest vessel is the last of four ordered by Baydelta. Another of the tugs also was delivered in 2008 to the Minette Bay Co., of Prince Rupert, British Columbia.

The five tugboats have provided steady work for Nichols Brothers for three years.

The $10-million tractor vessel is 100 feet long, weighs 585 tons, has up to 92 tons of pull and can reach a speed of 14 knots.

Nichols said that while at Langley, the tug will undergo a thorough testing of its engines and other systems, and its pulling power.

“We’ll run it hard and see if we can break it,” he said.