Seabulk Towing welcomes hybrid Spartan in Port Arthur
It’s been a while since any American operator invested in a large diesel-electric hybrid tugboat. This year, Seabulk Towing will welcome two.
The first boat is the 98-by-43-foot Spartan, built by Master Boat Builders of Coden, Ala., using the RApport 3000 design from Robert Allan Ltd. It will be followed this summer by Titan. The order is in addition to two 98-foot Rotortugs built by the same shipyard.
Spartan represents many firsts, including the first hybrid for Seabulk Towing, based in Fort Lauderdale, Fla. It’s also the first hybrid tug project for Thompson Tractor, a Caterpillar and Berg Propulsion dealer in Mobile, Ala., that was a key partner in the project.
Spartan arrived in its new homeport of Port Arthur, Texas, around March 15. A few weeks later, the tug’s crew was acclimating to the vessel and its hybrid propulsion system. Capt. Chris Y’Barbo said the tug performed admirably during the delivery voyage from Alabama to Port Arthur through 6- to 8-foot seas.
“It’s awesome,” he said of the vessel as it underwent final outfitting in Orange, Texas. “It did better than I thought it would do in those conditions.”
The hybrid powerplant on Spartan consists of two 2,550-hp Caterpillar 3512 main engines, along with two 565-kW Cat C18 gensets and a third 200-kW Cat C7.1 genset. Lastly, 560-kW ABB electric motors are installed aft of each Berg z-drive. Total installed horsepower, including the electric motors, is more than 6,600.
Berg, based in Sweden, supplied the electrical integration technology, including the power management system and electrical switchboard, according to Richard Tremayne, marine business manager for Thompson Cat, which also distributes Berg components.
There aren’t many diesel-electric hybrid tugboats operating in the United States. Harbor Docking & Towing, located in nearby Lake Charles, La., operates two vessels: Ralph and Capt. Robb. San Francisco-based Baydelta Maritime operates one hybrid tugboat. The three, which share a similar diesel-electric platform, were delivered in 2019.
The Great Lakes Towing Co., of Cleveland, operates three smaller hybrid tugs that use a different system to achieve a similar result.
The hybrid system on Spartan has four main modes: standby, eco, mechanical and power. Standby uses only the hotel generator for power. In eco mode, one or more generators send power to the ABB electric motors that turn the z-drives. The system automatically spools up generators as the operator demands more power. Power mode uses electricity from the three gensets and electric motors in tandem with the two Cat main engines. Mechanical mode reverts to the twin Cat main engines and disengages the electric motors.
The versatile system allows operators to downsize their main engines from a 3516 to a 3512 while achieving similar top-end performance, Tremayne said. Additionally, the tugs burn less fuel and generate lower emissions than a traditional twin-screw ASD tugboat. More time spent in eco mode means less wear and hours on the main engines, which reduces maintenance.
“The objective for this vessel was really a few things, with one being flexibility and being able to customize how the vessel is being operated to suit the actual operation,” said Lawren Best, director of design development for Robert Allan, Ltd., of Vancouver, British Columbia.
“The hybrid system allows the tug to do about 6 knots on one genset and about 9 knots on two gensets,” he continued. “That allows for reduced running hours on the main engines when they are just doing transits at slow speeds. But when they need to do ship handling or escort work the mains are fired up and this gives them continuous bollard pull capacity.”
Running the tug in fully-electric eco mode can give the operator much better control at slow speeds. The electric motors can turn the propeller as slowly as one rpm — a plus in situations where finesse is required.
Running in eco mode with the electric motors generates about 25 tons of bollard pull. It jumps to almost 83 tons in boost mode with all systems running at full power.
The operator can select between modes with the touch of a button on the wheelhouse console. Toggling between modes takes only eight to 10 seconds, according to Y’Barbo. “I am still trying to get used to the different modes and trying to be as fuel efficient as possible,” he said in March.
The RApport 3000 tugboats come from proven lineage that began more than a generation ago with the 78-foot RApport 2400. The 3000 moniker stems from its length, at 30 meters (98 feet). Best described the vessel as an all-purpose ship-handling and escort tugboat.
“It benefits from having a flush deck that lowers the tow point, which increases the stability of the vessel,” Best said.
The 98-by-43-foot hull leaves plenty of space inside for crew accommodations and machinery. The engine room, for instance, has a large storage room on the port side for tools, the FM-200 fire suppression tanks and other equipment. The starboard side is empty for now, but it could hold batteries in the future to create a full electric hybrid system, engineer Buck Shoemaker said.
The primary hybrid electrical equipment is located in the z-drive room that’s also home to the Berg MTA 628 drives and ABB motors. A bulkhead and steel door separate this equipment from the main engine room.
“I came off of the Rotortug Triton, so I am used to taking care of five engines,” Shoemaker said.
Spartan’s wheelhouse is equipped with an Alphatron integrated bridge that houses four retractable touch-screen displays. Those screens show the JRC Sea Radar and a JRC River Radar, along with Alphatron GPS and autopilot. It also houses the Siemens alarm panel and controls for the JonRie InterTech winch.
The JonRie Series 225 double-drum escort winch on the bow is equipped with a Hagglunds hydraulic motor and a spring-set hydraulic release band brake. The winch holds 600 feet of 8.5-inch Samson Saturn-12 synthetic line. It can generate 50,000 pounds of line pull, and has a brake holding force of 720,000 pounds, according to JonRie President Brandon Durar.
The aft deck has a JonRie Series 424 hydraulic capstan with a 21-inch head. It has a line pull of 20,000 pounds and a mid-barrel load of 100,000 pounds, Durar said.
With nearly twice the acceleration of a traditional mechanical tug, the ability to scale power as needed and the possibility of adding batteries in the future, Spartan and Titan give Seabulk new tools for efficient ship assist. It will be interesting in the years ahead to see whether any other operators follow suit.