Shallow-draft Aurora is designed for the long haul

Crowley Maritime has enhanced its fuel delivery unit with a sturdy articulated tug-barge (ATB) that will operate in remote western Alaska.

The 4,000-hp Aurora pairs with the 55,000-barrel double-hulled barge Qamun through an innovative Intercontinental coupling system. The ATB meets International Maritime Organization (IMO) Polar Code and ABS ice class D0 standards and has a 4,300-mile range. It can operate in temperatures down to negative 20 degrees Fahrenheit.

Master Boat Builders of Bayou La Batre, Ala., built Aurora, while Gunderson Marine of Portland, Ore., built Qamun. Crowley Engineering Services, formerly Jensen Maritime, designed the 410-foot ATB for shallow-draft operations in the Kuskokwim and other winding Alaska rivers that are prone to shoaling. In a region with few assist tugboats, the ATB is maneuverable enough to dock itself in trying weather and sea conditions. 

Aurora and Qamun were expected to enter service in June 2021, joining Crowley’s fleet of seven tugboats and 10 tank barges already delivering fuel in western Alaska. The new ATB will be more efficient and resilient than traditional tugboats towing barges off the stern, according to Rick Meidel, Crowley Fuels’ vice president and general manager.

“It is about reliability, speed and making deliveries in weather conditions where we are not able to do it today,” he said in a recent interview. “Alaska is an austere environment. The seas are rough, and we can frequently get held up waiting for a break in the weather to reach the dock.”

The 108-by-46-foot Aurora is a smaller cousin to the 128-foot ATB tugboat Aveogan that Crowley placed into service last summer. The larger tug pairs with the 100,000-barrel Oliver Leavitt and works under contract to the Alaska-based refinery Petro Star. 

Aurora and Qamun will typically work in western Alaska from April to October before shifting to comparatively balmy southeast Alaska during the winter months. The ATB will make fuel deliveries to some of the most remote places in the United States and Canada during that seven-month season.

Specifically, the vessels will deliver 4 million gallons of fuel to Eareckson Air Station on Shemya Island. The outpost, home to about 175 U.S. Air Force personnel and contractors, is located 900 miles west of Dutch Harbor, Alaska. Its small dock lacks protection and is routinely battered by wind and surf, offering narrow windows to safely discharge cargoes. Unexploded ordnance from World War II in the small adjacent harbor makes anchoring particularly hazardous, leaving captains with few good options in poor weather.

Aurora also will push Qamun into Arctic Canada for annual deliveries to a remote mining camp near Roberts Bay, Nunavut. The mine is located near Victoria Island, more than 1,000 miles east of Prudhoe Bay, Alaska.

Closer to home, Aurora must safely transit up the narrow Kuskokwim River to Bethel and surrounding Native Alaskan villages in western Alaska. Design parameters required the tugboat to draw no more than 9.5 feet while carrying 15,000 gallons of fuel.

“That was the contract specification, but we hit that with 20,000 gallons of fuel on board,” said Dean Sahr, Crowley’s manager of new construction.

Maneuverability and the ability to reach terminals in all weather was another design imperative. Aurora, named for the aurora borealis, is powered by twin 2,000-hp GE 6L250 Tier 4 engines driving Schottel SRP 460 z-drives. Qamun is equipped with an 800-hp Schottel omnidirectional bow thruster to help guide the barge in and out of terminals.

“This will be a very maneuverable boat,” said Capt. Kenneth Graybill III, a staff captain for Crowley Petroleum Transport who oversaw construction and delivery. “That is one of the reasons they went with z-drives … so you can maneuver the whole unit safely without an assist tug.”

Aurora is expected to sail at 9 knots or faster with a loaded barge in 3- to 5-foot seas. Based on Aveogan’s performance in Alaska over the past year, Meidel expects the new ATB will exceed those projections.

“It will be able to get where it’s going faster (than a line-haul tugboat and barge) so we can expand our customer base and make more deliveries than we have done in the past,” he said.

Aurora has an unusually spacious interior owing to its 46-foot beam. It will operate with up to 11 crewmembers sharing seven cabins across three decks. Wireless internet is available throughout the vessel, and mariners can access an extensive on-demand TV and movie library. The crew spaces are rated for no more than 65 decibels when the ATB is underway.

“Crew ergonomics is really important to us,” Sahr said. “We just really put a lot of effort into making it comfortable because these guys are going to be so remote.”

Sahr expressed particular pride with the galley and comfortable open-concept mess. The kitchen area is equipped with gleaming stainless-steel appliances and surfaces for easier upkeep and maintenance. The mess has a large table facing a 60-inch TV with access to the on-demand entertainment library.

“The galley standard is the best we have in the Crowley ATB fleet,” Sahr said.

The bridge resembles that of an oceangoing ship, with plenty of space to move around. The controls are laid out like a tractor tugboat and designed for a single operator. The helm chair along the centerline is placed between z-drive controls and a modern suite of Furuno navigation electronics. Forward-facing helm stations also have been installed on the port and starboard sides of the wheelhouse.

Aurora has Inmarsat and Iridium satellite systems to ensure stable communications even in high latitudes. Crew communicate internally through an intercom system and Icom handheld VHF radios.

Like most modern ATB tugboats, Aurora is designed to stay in the notch. The tugboat has a tapered square bow that pairs with Qamun through an Intercontinental Model 34 coupler. The coupler helmet, like the one on Aveogan, has a wave design on one side and a smooth friction plate on the other. Hydraulic pressure on the wave side maintains the connection between tug and barge in dynamic conditions.

Aurora is equipped with a sturdy H-bitt and a Coastal Marine Equipment capstan on the aft deck. The capstan is well suited for tightening mooring lines, retrieving anchors and, in an emergency, handling a hawser connecting the tug and barge.

The 350-by-88-foot Qamun, an Inupiaq word for “low sled,” has 12 tanks, 10 of which hold 5,000 barrels while two hold about 3,000 barrels. The barge will load some of its cargo at the Petro Star refinery in Valdez, but much of the product it delivers will come from foreign-flagged tankers that loiter in international waters each summer. Qamun can load 6,000 barrels of cargo an hour while alongside another ship, according to Crowley.

The barge has two anchors, one fore and one aft, that allow the ATB to push close to shore in small communities that lack terminal facilities. The 800-hp electrically driven Schottel jet thruster is located at the bow, forward of the cargo tanks and aft of the forepeak.

Electrical power on the barge comes from three 436-hp John Deere engines paired with selective catalytic reduction systems that meet IMO Tier 3 standards. Tanks for the barge engines hold 1,700 gallons of urea and 14,000 gallons of diesel.

“The electrical and control system on Qamun is the most technically complex that we have installed on a barge,” said Richard Hunt, vice president and acting general manager at Gunderson Marine. “The integration of all the systems into a central command and control location has been very challenging (but it will) provide the barge crew with enhanced safety and operational efficiencies.”

MarFlex, based in the Netherlands, supplied three electric deep well pumps for Qamun. The company also outfitted the barge with two ballast pumps, two cooling water pumps and one variable-speed drive system. Other equipment on Qamun includes Coastal Marine Equipment winches, two burly North Pacific Crane Co. cranes and a Panasia ballast water treatment system. The barge can hold nearly 1.3 million gallons of ballast water.

As of early May, Aurora was underway to the West Coast, where it will pick up Qamun in Portland. From there, the vessels will sail north to Alaska, where plenty of work awaits.

Categories: American Tugboat Review