As of this spring, Crowley was close to taking delivery of the 82-foot all-electric tugboat eWolf from Master Boat Builders.
The vessel, which will work in San Diego, Calif., is the first all-electric tugboat built in the United States. It was designed in-house by Crowley Engineering Services, the company’s design and naval architecture firm.
Once complete, eWolf will be powered by two 2,100-kW (2,816-hp) Ramme electric motors drawing electricity from battery banks installed below deck. Those motors will turn Schottel z-drives. Bollard pull is estimated at 70 tons, and it will be capable of 12 knots.
Although the tugboat is designed for fully electric operations, it does have some redundancy built in. There are two 400-hp diesel-powered generators on the main deck to charge batteries during long voyages. Crowley has said it does not expect to use the gensets during typical operations.
Corvus supplied the six battery banks with 6.2 megawatt hours installed below deck that store energy for the electric motors. The system will have enough power to perform two ship-assist jobs without the need to recharge. ABB integrated the electrical system to supply propulsion and hotel power.
“The battery system is modular and can be maintained and upgraded for future battery technology improvements without any significant modifications to the vessel,” Crowley said of the system.
Electric tugboats represent a major shift in tugboat design and outfitting. The engine room, for instance, has no main engines. As a result, eWolf was built without exhaust stacks. The result is true 360-degree visibility for the operator.
The zero-emission propulsion package will provide Crowley with some operational savings. For one thing, it will burn about 30,000 gallons less diesel each year than a similarly sized tugboat. Longer term, the emissions benefits are substantial.
Crowley estimates it will generate 178 fewer tons of nitrogen oxide (NOx), 2.5 fewer tons of diesel particulate matter, and 3,100 fewer metric tons of carbon dioxide (CO2) versus a conventional tug.
Bisso Towboat
Bisso Towboat Co., of Luling, La., will take delivery next year of a 5,000-hp z-drive tugboat currently under construction at Main Iron Works in Houma, La.
The new vessel will share the same hull as the 6,008-hp Capt. Joseph Bisso, which entered service in January 2022, albeit with a different propulsion package.
The new tug will be powered by two 2,500-hp Caterpillar 3516E Tier 4 main engines driving Kongsberg US205S z-drive thrusters with 94.5-inch stainless-steel propellers in stainless-steel nozzles. Bollard pull is estimated to be 66 tons.
Electrical power will come from two 118-kW Caterpillar C4.4 generators, and a JonRie Series 240 escort winch will be installed on the bow.
Once complete, the new tug will be the sixth z-drive tugboat Main Iron Works has built for Bisso Towboat in nine years, and the 10th z-drive tug in the company’s fleet. It will join Bisso’s other tugs performing ship-assist work on the Lower Mississippi River.
Crescent Towing
Crescent Towing of New Orleans, La., will soon take delivery of its first Tier 4-rated tugboat from Blakeley BoatWorks of Mobile, Ala.
The 92-by-38-foot Angus R. Cooper II also is the first Tier 4 tugboat delivery for Blakeley BoatWorks, a sister company to Crescent Towing.
Angus R. Cooper II will share the same Jensen/Crowley Engineering Services design as seven other ship assist tugboats in the Crescent Towing fleet, including Mardi Gras, South Carolina and Arkansas.
It will be powered by two 3,004-hp Caterpillar 3516 engines paired with Kongsberg z-drives. Electrical power will come courtesy of two John Deere four-cylinder engines, and Markey Machinery supplied the Class II electric hawser winch.
“Angus R. Cooper II is different from the other Jensen-designed tugboats in our fleet because of the Caterpillar engines whereas all of the previous tugs have GE engines,” said Ben Morvant, Crescent’s senior operations manager. “Also, the Angus R. Cooper II will join the Bulldog as the second full FiFi-class tug in our fleet.”
Angus R. Cooper II also is built to full ABS class, Maltese Cross and Escort Class.
Crescent Towing operates tugboats in Mobile, New Orleans and Savannah, Ga. Angus R. Cooper II will be assigned to Savannah.
Moran Towing
Moran Towing of New Canaan, Conn., has two tugboat projects underway on two coasts. Washburn & Doughty of East Boothbay, Maine, is building two 86-by-36-foot z-drive tugboats that are sister tugs to Andrew Moran and Dennis Moran, both of which entered service last spring.
The new tugs, which are not yet named, are scheduled for delivery in 2024. They will feature a design from Crowley Engineering Services and deliver 60 metric tons of bollard pull. Markey Machinery will supply the hawser winch.
The two tugs will be powered by two 2,550-hp Caterpillar 3512 Tier 4 engines paired with Kongsberg drives. John Deere 4045 generators will supply electrical power.
The two 86-by-36-foot tugboats ordered from Master Boat Builders will be the first deliveries for Moran from the Coden, Ala., shipyard. They will have similar features as the tugs under construction at Washburn & Doughty.
Signet Maritime
Signet Maritime is building a new generation of tugboats that will escort and assist deep-draft tankers calling on the Port of Corpus Christi, Texas.
The tugboats, Signet Sirius and Signet Capella, are currently under construction at Signet Shipbuilding & Repair in Pascagoula, Miss. They are tentatively scheduled for delivery in July and November, respectively.
Both feature the Advanced Rotortug design from Robert Allan Ltd. The vessels will have three MTU engines and three Kongsberg z-drives in a triangular layout under the hull. Electrical power will come from R.A. Mitchell RAMCO generators, and bollard pull will be 92 metric tons.
In another milestone, the tugs are the first commercial vessels in the United States designed entirely using a three-dimensional model. •