Island Tug and Barge upgrades fleet with z-drive ATBs


British Columbia’s Island Tug and Barge has a history of innovation, and the company is taking another step forward with a new class of z-drive articulated tug-barge (ATB) units.

The first new ATB tug, Island Raider, is due in July from Island Tug and Barge’s (ITB) shipyard near Vancouver, B.C. The second, Island Regent, will be delivered in late 2018. The Canada-flagged tugs will push 25,000-bbl petroleum barges.

Tidewater Transportation of Vancouver, Wash., bought ITB in September 2017. These ATBs will be joining ITB’s current fleet of eight tugs and 11 barges. They’re the first, and likely the last, built in-house.

Capt. Ferdi van de Kuijlen, ITB’s vice president of operations, said the new ATBs will be more maneuverable and cost effective versus traditional towed barges.

“The project team spent months working on an ATB design to ensure the unit meets all the requirements of our customers and regulatory agencies,” said van de Kuijlen.

Island Tug and Barge built Island Raider in a temporary shipyard space near Vancouver, B.C. Launch was scheduled for early June 2018.

Casey Conley

Former CEO Bob Shields, who planned the two ATBs before selling the firm, described numerous benefits from the ATB units. In particular, he noted time lost handling the towline at landings or shortening up in narrow passages.

Naval architects at Robert Allan Ltd. in Vancouver, B.C., developed plans for the ATBs. Using computational fluid dynamics (CFD), designers considered several hull forms — including a catamaran. Ultimately, they abandoned that plan after realizing the monohull would be 25 percent more efficient.

Through digital trial and error with CFD modeling, designers developed an ATB tug that becomes effectively one unit when coupled with the barge.

“If you are designing a tug to be always in the notch, it’s going to be (relatively ineffective) on its own,” said Mike Fitzpatrick, president of Robert Allan Ltd. “But you are then able to design it so the difference between an ATB and conventional propelled vessel is (close to) negligible.”

Maneuverability benefits from z-drives apply across vessel classes, whether it’s a harbor tug, inland towboat or ATB. Fitzgerald added that the price difference between ASD and traditional propulsion is often smaller than many operators and shipyards expect.

After buying Island Tug and Barge, Tidewater hired Justin Nichols of Nichols Marine Services to oversee construction of the z-drive ATB tugs.

Casey Conley

“When you actually go through the full construction equation and look at the fact that you don’t need a gearbox, you don’t have stern tubes and rudders and steering gear, the cost differential is much less than you might otherwise think.”

The result of these design efforts is an 82-by-41-foot tugboat with a relatively shallow 12-foot draft. These dimensions fall under the 25-meter and 500-ton SOLAS limit. “We got a very large, comfortable tug on the hotel side as a bonus,” Shields explained.

Island Raider will be paired with ITB Resolution, while Island Regent will push ITB Reliant. Those barges, built a decade ago, were modified at Vancouver Drydock with specifically designed modules for the new pusher tugs.

The tugs are under construction in an industrial park on Annacis Island alongside the Fraser River. Although previous management began the project, Tidewater committed to finishing them at the Annacis Island yard. During a March visit, Island Raider was undergoing final outfitting while workers assembled Island Regent’s hull and house modules inside a nearby construction building.

Tidewater hired Justin Nichols of Nichols Marine Services in Washington to oversee the ATB construction. The job employs 60 people from nearly a dozen subcontractors. Although the work has taken longer than expected, the product is top-notch, he said.

The two tugs have broad bows, which are designed to fit tightly in the barge notch for optimum water flow efficiency. Forward, a raised forecastle deck contains an Articouple pin system built by Taisei Engineering Consultants. The self-aligning coupler system lets the tug adjust for changing barge draft by remote control from the wheelhouse in less than a minute.

Z-drives will allow for better maneuverability than with traditional towed barges.

Robert Allan Ltd.

The steel main deckhouse continues aft from the forecastle and contains accommodations. There are six cabins overall, including four singles and two shared double bunk rooms. The standard crew is four — captain, mate and two deck hands.

The next level up includes a wet room, large mess/lounge area and a fully stainless-steel finished galley. Stairs will lead up to a smaller cabin area for the HVAC and wheelhouse electronics. Above that is a large wheelhouse on a tower, with a full walk-around catwalk located 40 feet above the water.

Alphatron Marine developed the wheelhouse layout and view for optimal situational awareness. The tug bridge has integrated voyage data recording as well as data logging capability for keeping track of courses and fuel consumption, among other things.

The vessels will use only electronic charts, eliminating the chore of manual updates while creating more space on the bridge. Closed-circuit cameras are installed throughout the boat for bridge monitoring and management. An infrared camera mounted on the searchlight also displays on a bridge monitor.

Propulsion comes from a pair of V-12, IMO Tier II-certified, Cummins KTA38 diesels each generating 850 hp at 1,800 rpm. Carbon fiber shafts link the mains with twin Rolls-Royce US 105-P9 z-drives. The engines and their systems are entirely independent, allowing propulsion if one sustains a catastrophic failure.

Propulsion comes from twin Cummins KTA38 diesel engines turning Rolls-Royce z-drives through carbon fiber shafts.

Casey Conley

Forward of the engine room, the domestic equipment space includes a workshop, making good use of the ample space available. Forward of that, an electric over hydraulic pump for the coupling pins is located just below the main deck pin rooms.

The ATBs are not outfitted with a stern winch, meaning they will lack conventional towing capabilities. The vessels will serve tank barge routes between Vancouver, Vancouver Island and Puget Sound ports, all of which are in relatively sheltered waters. During an emergency, a towing bitt mounted on the foredeck will hold the emergency towing cable on the barges, allowing the tug to hold the barge in position.

The barges are fitted with 500-hp Schottel omnidirectional pump jets at the bow. These thrusters, common on inland waterway barges in Europe, draw water through a flat grid on the barge’s bottom. It is then driven out through thruster ports that give the barge 360-degree propulsion control. This, together with the tugs’ z-drives, will allow the ATB unit to effectively walk sideways parallel to its moorings.

The remote-controlled thruster can propel the tug and barge unit at 5 knots. When transiting narrow sections of the route, such as the Narrows in Vancouver Harbor, it will be in “standby” mode for immediate response. For mooring, the ATB unit can stop well off the dock and walk sideways for a gentle and controlled landing. Unlike conventional bow thrusters, these Schottel units are still effective while the ATB is underway.

The new ATBs are projected to have remarkable efficiencies compared with a traditional towing setup. One of ITB’s existing tugs, Island Scout, tows roughly 25,000-bbl barges now at about 5.8 knots loaded and about 7 knots empty. With identical twin 850-hp Cummins KTA38 mains, the new tugs are projected to make 8 knots loaded and 10 knots empty at the same rpm with the same capacity barges.

Although these vessels predated Tidewater’s ownership, new management is looking forward to delivery.

“We’re excited,” said Island Tug and Barge President Adrian Samuel. “They’ll be working the second they’re commissioned.”

Highlights: Z-drive propulsion unique on ATBs • Broad bow resembles river towboat • Barges fitted with 500-hp pump jets
By Professional Mariner Staff