ATHENA | Crowley, Seattle, Wash.

Athena’s 96-ton bollard pull makes it one of the most powerful tugboats in the world under 80 feet long.
Athena’s 96-ton bollard pull makes it one of the most powerful tugboats in the world under 80 feet long.
Athena’s 96-ton bollard pull makes it one of the most powerful tugboats in the world under 80 feet long.


Athena solidifies Crowley’s Puget Sound towing fleet
Crowley’s latest ship-assist tugboat packs a lot of power into a compact package.  

Diversified Marine delivered the 77-foot Athena earlier this year using Robert Allan Ltd.’s proven RApport 2500 design. The nearly 6,800-hp tug delivers more than 90 tons of bollard pull, making it one of the world’s most powerful tugboats under 80 feet long. 

“We like this model of boat, we like the design and we like the maneuverability,” said Paul Manzi, Crowley’s vice president of asset management. “The pilots tend to like them because as ships get bigger and spaces get tighter, these smaller, more powerful tugs become a really important part of the tool set for docking and undocking ships.”

Brusco Tug & Barge of Longview, Wash., initially ordered the vessel from Diversified, its longtime partner located along the Columbia River in Portland, Ore. Crowley operates Athena on charter, along with its sister tugs Hercules, delivered in 2020, and Apollo, which entered service last spring. 

All three are powered by Caterpillar Tier 4 engines driving Berg MTA 628 z-drives. They make up to arriving tankers and containerships through Markey electric winches on the foredeck. 

Athena is based in the Puget Sound, where it primarily escorts and docks containerships calling in Seattle and Tacoma. Crowley operates Hercules in Los Angeles-Long Beach, and runs Apollo in and around San Francisco Bay. 

“The three of them together work out really well,” Manzi said. “With Athena, we now have one on the Puget Sound, one in the Bay Area and one in Long Beach.”

Robert Allan Ltd. of Vancouver, B.C., developed the RApport 2500 series from its time-tested RApport 2400 platform released a generation ago. These simple vessels, typically used as dayboats, are known for being nimble and maneuverable when working alongside a ship. 

The 2500-series tugs are 25 meters long, hence the name. They are a meter longer (3.28 feet) and 10 feet wider at the beam than the 2400 series tugs. They carry the same “slippery” hull form that helps the operator steer into the best position to push or pull. The sturdy skeg is designed to improve escort capabilities. 

Athena, like Apollo, is weighted down with nearly 8 tons of scrap metal in the skeg to further enhance its escort function, according to Henry Reeve, a project manager and senior naval architect with Robert Allan Ltd. The weight makes the tug more stable but also makes it sit lower in the water. Reeve and his team used computational fluid dynamics to strike the right balance on the design of both vessels. 

“We did adjust the deckhouse design slightly to move the engine room ventilation intakes to the side of the house,” Reeve said of Athena. “But the remainder of the design was the same.”

Athena’s powertrain consists of Caterpillar 3516E main engines turning Berg z-drives.
Athena’s powertrain consists of Caterpillar 3516E main engines turning Berg z-drives.

The powerplant, however, is a little different on all three tugs. Athena is the most powerful tugboat of the three, with twin Tier 4 Cat 3516E engines producing just under 6,800 total hp. The mains turn 106-inch four-bladed propellers in Berg MTA 628 z-drives. Berg also supplied the electric steering package. 

Bollard pull reaches 96 tons ahead and 94 tons astern. Apollo and Hercules, which have slightly less powerful engines, are rated for 90 and 88 tons, respectively. “To have this much bollard pull, it’s massive for a boat of that size,” Manzi said of Athena. 

Two Cat C7.1 auxiliary engines driving 150-kW generators provide electrical power. An FM-200 fixed fire suppression system provides fire protection in the engine space, while off-ship firefighting consists of a 1,300-gpm forward-facing Elkhart Brass monitor supplied by a 1,250-gpm Carver pump. 

Crowley has set a goal of becoming the most sustainable transportation provider in the Jones Act trade. The company, based in Jacksonville, operates four Tier 4 harbor tugboats — including the tug Valor that has been retrofitted — and has two ships operating in the Puerto Rico trade powered by liquefied natural gas. 

Meanwhile, it has designed the first-ever fully electric U.S. tugboat, eWolf, which is slated for completion next year. The company also has designed a second electric tugboat with gensets to charge the batteries that will offer a longer endurance. 

Manzi considers the company’s new Tier 4 vessels from Diversified to be state-of-the-art, and among the least-polluting tugs in the United States. They also burn less fuel than a comparably powered older tugboat. Longer term, they represent an effective stand-in as the company pursues a hybrid and fully electric future. 

“These high-efficiency Tier 4 engines are our bridges to that near-zero and zero emissions technology,” Manzi said. “We are building eWolf to a similarly-sized platform, and we are looking to put the same amount of bollard pull into the hybrid designs we are developing.”

“So right now, it is about getting our crews used to the higher power and more maneuverable platform these tugs offer,” he continued. 

Athena escorts and assists ships using a Markey winch installed on the bow.
Athena escorts and assists ships using a Markey winch installed on the bow.

Athena makes up to ships using a Markey Machinery Co. DEPC-52 electric winch on the bow that can hold 750 feet of 10-inch line. The winch is equipped with Markey’s Render/Recover system and NexGen automatic controls, said Scott Kreis, Markey’s vice president of sales and engineering. 

“We have larger, more powerful winches for purely escort applications, but to date, the DEPC-52 is Markey’s highest capacity winch for harbor tugs that perform ship assist missions,” Kreis said in an email. 

While the RApports Series 2400 tugboats were typically outfitted as dayboats, the new series features accommodations for six crewmembers. The three cabins are located below deck, while the main deck has a galley and crew lounge available during downtime between jobs. 

The wheelhouse is outfitted with a suite of high-end navigation components. This includes a Transas navigation system, Furuno radar, GPS and AIS system. The vessel also has a Furuno loud hailer and Standard Horizon radios. 

Crowley also installed a Reygar BareFLEET remote monitoring system that allows shoreside personnel to monitor the engines and speed while the tug is working. The system, for instance, will track fuel consumption to determine whether the vessel could be operated more efficiently and burn less fuel. 

“The value of the BareFLEET system is we can see it from shore,” Manzi said. “Our operations guys get pinged when the vessels are running hard. The idea isn’t to be Big Brother watching the crews, but we want to give people the right tools to do the job in the most efficient ways possible.”

Diversified is currently building a fourth boat in the series for Brusco Tug & Barge, and for now it is not clear which company will operate the vessel. Redd said the tug will be built to the same specs as Athena. Delivery is slated for early next year.

“They are just really nice boats,” Redd said of the three tugs in the series. “They pull like gangbusters and everybody that operates them seems to like them. They are just a really neat boat.”

Looking back at the build, Redd is proud that all three were delivered during the Covid-19 pandemic, which has impacted shipyards across the United States and the world. Athena also was built during a time of rapid inflation and supply-chain turmoil. 

“We built it during Covid, so that in itself is quite an accomplishment,” Redd said. 

Crowley put Athena to work this spring in and around Seattle. The company has been pleased with the results. “She is one of the most powerful boats working in that area,” said Manzi. “We can put that boat in places we can’t with our other tugs.”