Crowley’s rugged ice-class ATB built to withstand Alaska’s harsh climate


Alaska has notoriously challenging weather conditions and climate. Crowley Maritime built an articulated tug-barge (ATB) rugged enough to safely sail through these icy waters and nimble enough to steer itself into berth.
The 128-foot Alaska-class tugboat Aveogan is paired with the 100,000-bbl Oliver Leavitt. The tug and barge pair up through an Intercon C-Series coupler with a first-of-its-kind “modified wave” lightering helmet to allow for ship-to-ship transfers. Propulsion comes from twin 3,384-hp GE Tier 4 engines paired with Schottel z-drives.

The double-hulled ATB meets both ABS Ice Class and IMO Polar Code standards. The tug is equipped with a closed-loop ballast system that transfers water between the tugboat and barge as the tugboat burns fuel. Oliver Leavitt is outfitted with spill response equipment to protect Alaska’s pristine waters and coastlines.
Crowley Shipping’s petroleum services group will operate the ATB for Crowley Fuels Alaska. Jensen Maritime Consultants designed the ATB, and Bollinger Shipyards built the vessels at its Louisiana yard. Petro Star Inc., based in Anchorage, chartered the vessels for Crowley to carry fuels to some of Alaska’s most remote communities, including Dutch Harbor, located 700 nautical miles from Anchorage.

“It is a very capable ATB,” said Lev Yampolsky, Petro Star’s vice president of logistics and terminal operations. “The capabilities we will get with this ATB from Crowley are things we are very excited to see: the ability to move fast, switch cargo and quickly prepare the barge for different cargo configurations. That is going to give us good operational flexibility.”

Aveogan features an advanced suite of Furuno navigation electronics.

Crowley Maritime

Aveogan is named for Oliver Leavitt, a former chairman of Arctic Slope Regional Corp. (ASRC) and a current member of the company’s board of directors. Aveogan is Leavitt’s Iñupiat name. ASRC is an Alaska Native corporation that acquired Petro Star in 1987, three years after it launched.

Petro Star operates two refineries — one in Valdez and the other near Fairbanks — that make jet fuel, heating oil and other refined products for the Alaska market. Its commercial distribution arm uses ATBs to deliver fuels to hubs like the Port of Alaska in Anchorage, as well as the far-flung fishing outpost on St. Paul Island. Petro Star also supplies U.S. military jet fuel in Alaska.
Crowley subsidiary Jensen Maritime of Seattle designed Aveogan and Oliver Leavitt to work in Alaska’s challenging environment. Its naval architects used computational fluid dynamics to optimize the hull form for efficiency while underway, according to Jay Edgar, Jensen’s vice president of engineering. The work paid off: Aveogan and Oliver Leavitt should maintain at least 10 knots when pushing a loaded barge.
Speed is a huge advantage when working in a state as big as Alaska. “If you think about the map and the ability to go 1 to 2 knots faster, over 1,000 miles, it adds up,” Yampolsky said.
Designing Oliver Leavitt to ABS Ice Class D0 standards required additional framing and thicker hull plating at the bow to withstand first-year ice. The 400-by-85-foot barge is beamier than barges with similar capacity to maintain a shallow draft required in some parts of coastal Alaska. Its maximum draft at full capacity is 22 feet.

The Intercon C-Series coupler on Aveogan has the first-of-its-kind “modified wave” lightering helmet allowing for ship-to-ship transfers.

Crowley Maritime

The ATB is packed with innovation and industry firsts. One is the patented closed-loop freshwater ballast management system that pumps ballast water back and forth between the tug and a 79,000-gallon storage tank located in Oliver Leavitt’s aft rake. The first-of-its-kind system eliminates the need for ballast water treatment and means the tug has zero ballast discharge. Oliver Leavitt is outfitted with two Panasia ballast water treatment systems operating at 350 cubic meters per hour.
“As you’re burning fuel on the tug, instead of having to adjust the coupler pins, we can transfer ballast from the barge retention tank back to the tug to keep on a constant draft without overloading the pin system,” said Christopher Clark, Crowley Maritime’s manager of new construction.

The Intercon C-Series Model 50 coupler system with a “modified wave” lightering helmet design marks another industry first. The aft side of the helmet has a smooth friction plate, while the forward face has a wave pattern without the “teeth” design found on many coupler systems. Hydraulic pressure on the wave side maintains the connection in dynamic sea conditions.

“This ATB will be doing coastal transits in Alaska waters most of the time, but it is also able to conduct ship-to-ship transfers from a larger vessel,” said Matt Yacavone, a vice president at Crowley Fuels. “Larger tankers can’t get into some of the ports … so this vessel will be able to go alongside and pick up a smaller cargo and carry it to the terminals.”

Vessels working in Alaska — whether they’re fishing vessels, ships or oceangoing ATBs — must be robust enough to get where they’re going. They also must be maneuverable enough to get into berth in smaller ports, many with shorter docks and challenging geography. Crowley solved this problem with the 483-foot ATB by installing Schottel SRP 560 z-drives.

Jensen Maritime Consultants designed Aveogan with a patented freshwater ballast transfer system between the tug and barge.

Crowley Maritime

“The z-drives offer the vessel much more maneuvering ability when we’re going into some of the restricted ports where they don’t have assist tugs to get into the dock or mooring location,” Yacavone said.
The ice-hardened z-drives and Vulkan carbon-fiber shafts are paired with twin 3,384-hp GE 8L250 engines that meet EPA Tier 4 emissions standards. The tugboat achieved 97 tons of bollard pull during testing and trials at Bollinger. Ship service power comes from three 99-kW John Deere gensets; a fourth John Deere 88-kW emergency generator is installed to meet the IMO International Convention for the Safety of Life at Sea (SOLAS) requirements.

Aveogan is one of the first U.S. ATBs specifically designed to meet IMO Polar Code standards for service in Alaska. Under these rules, the vessel designers and operators performed risk assessments and considered the potential hazards of operating in polar waters to determine additional features necessary in such a challenging environment. The tug also was designed to maintain stability with a limited amount of ice accumulation.
Aveogan can support up to 11 crewmembers, and its breadth ensures plenty of space for each person. The main deck has a mess-lounge and galley, a self-serve area that also functions as a food prep area, a pantry and laundry room. It also has a well-equipped exercise room and coupler pin rooms accommodating the Intercon equipment.
Three single cabins and two double cabins are located on the 01 deck, along with the emergency generator room and heating and cooling machinery. The 02 deck has another double cabin, along with four singles including cabins for the captain and chief mate. The 03 deck has a dedicated stateroom for a pilot.

The tug is equipped with Schottel z-drives for maneuverability in compact Alaskan ports.

Crowley Maritime

The electronics room and a small head lead up to the wheelhouse with a 50-foot height of eye above the waterline. Beier Integrated Systems of Houma, La., designed and installed the wheelhouse navigation electronics primarily consisting of Furuno equipment. Off-ship communication equipment includes an Iridium FleetBroadband system and Cobham SAILOR GMDSS.

Aveogan has a robust deck equipment package that includes a 300,000-pound capstan and forward winch, both supplied by Oil States. A 1,000-pound Toimil knuckle-boom crane is installed on the boat deck for loading provisions. Marsis supplied the electrically driven fire pump and manually operated monitor installed on the 03 deck. The tug has a 2,800-gallon tank for firefighting foam.

“Given the Aveogan/Oliver Leavitt’s strong performance capabilities, Crowley Fuels will be working closely with Petro Star to operate the vessel to meet their fuel transportation and distribution needs to serve Alaska,” said Rick Meidel, vice president and general manager of Anchorage-based Crowley Fuels Alaska. “The vessel’s functions add a new dimension for our fuel supply services in the state.”

Oliver Leavitt is divided into 12 cargo tanks with piping that allows for six segregated cargoes.

Each tank is fitted with dedicated electric deep-well pumps supplied by MarFlex, and a vacuum stripping system that removes virtually all cargo residue after discharge. The barge has a combination windlass/winch that handles the bow anchor and four additional electric winches provided by Oil States, allowing for a total of eight mooring lines on powered drums.
North Pacific Crane Co. supplied Oliver Leavitt with two 10-ton cranes primarily used to handle hoses for loading or discharging petroleum products. The cranes also can lift the three 8-by-18-foot Yokohama pneumatic fenders permanently stored on the barge into position during ship-to-ship transfers. Oliver Leavitt has a self-contained hydraulic boom reel with 2,000 feet of inflatable boom that can be deployed using a dedicated 17-foot aluminum skiff.

Aveogan and Oliver Leavitt will work on charter for Petro Star, an Alaska-based fuel refiner and distributor.

Crowley Maritime

Aveogan and Oliver Leavitt represented a unique project for Bollinger Shipyards in Amelia, La. The COVID-19 pandemic posed entirely new challenges during the final weeks before delivery; completing the vessel in those conditions, Yampolsky said, deserves recognition.
Chris Remont, executive vice president for new construction at Bollinger Shipyards, said the yard worked closely with the Jensen and Crowley team throughout construction. This collaboration, he said, allowed crews to address issues as they arose. It ultimately led to a high-quality finished product the yard and its workers are proud of.
“I think that, with all of the barriers and circumstances that surrounded the project, given the pandemic in particular — and especially the complex and innovative design of the vessel — provided for a truly impressive tug that was delivered in spite of issues that were presented in the project,” Remont said.

Aveogan and Oliver Leavitt is the first Crowley ATB designed specifically for the Alaska trade, but it won’t carry the distinction for long. Master Boat Builders in Bayou La Batre, Ala., is building a new Jensen-designed Tier 4 ATB tug that will serve Western Alaska with a 55,000-bbl barge that Greenbrier Marine (formerly Gunderson) is building in Portland, Ore. Like Aveogan/Oliver Leavitt, the vessels will meet ABS Ice Class and IMO Polar Code Standards.

The two new ATBs will give Crowley a continued foothold in the Alaska market with some of the most innovative and capable vessels working anywhere in the world.

Highlights: Meets IMO Polar Code and ABS Ice Class D0 • Closed-loop freshwater ballast transfer system • Z-drive propulsion
By Professional Mariner Staff