McAllister solidifies fleet with new Tier 4 tugs


McAllister Towing and Transportation decided to build Capt. Brian A. McAllister, the most powerful docking and escort tug in its fleet, to handle big containerships expected in East Coast ports following the recent expansion of the Panama Canal.

This spring, the 6,772-bhp Capt. Brian was nearing completion at Horizon Shipbuilding in Bayou La Batre, Ala. A sister vessel, Rosemary McAllister, was scheduled for delivery this summer, and McAllister has exercised an option on a third tug. The lead boats, named after the company’s chairman and his wife, were designed by Seattle-based Jensen Maritime Consultants.

Martin Costa, McAllister’s engineering manager, said Capt. Brian “is set up for extra-large container vessels.”

The canal’s new locks are 1,400 feet long, 180 feet wide and 60 feet deep, permitting ULCVs (ultra large container vessels) to pass between the Atlantic and Pacific oceans. East Coast ports served by McAllister could see containerships up to 1,200 feet long with beams up to 160 feet. When they arrive, Brian and Rosemary will be ready to escort them safely in and out of the harbor and assist them to and from their berths.

In addition to handling containerships, these tugs are set up for rescue operations and can work with LNG.

McAllister wants these boats to be as versatile as possible. Capt. Brian is equipped with a powerful Markey Machinery bow winch. The 100-hp electric single-drum hawser winch boasts 350,000 pounds of line pull and an adjustable brake holding force of 253 tons. It also features Markey’s render/recover automatic tensioning system.

Costa said that winch is more than enough for ship escorting and docking, meaning the tug will be well suited to handle larger ships at the port of New York/New Jersey, where Capt. Brian A. McAllister is expected to work.

Even if large ships don’t materialize in the numbers East Coast ports are expecting, these tugs will have other ways to earn their keep. Consider the electric Markey winch on its stern, a single-drum towing winch that can hold 2,500 feet of 2.5-inch wire. Less visually striking but just as important is the hydraulic three-pin towing system on the stern with its hold-down block and stern roller.

These crucial elements let Capt. Brian serve as a rescue vessel. While the primary mission is ship assist and escort, if a ship loses propulsion or steering, or a barge breaks loose and could run aground, these tugs can tow it to safety. “If one breaks down, we can go get it,” Costa said. “We can do ocean towing if necessary.”

McAllister installed a Markey TES-40-75 winch on the stern to provide versatility as towing jobs arise.

These tugs also have the ability to escort liquefied natural gas tankers (LNG). With the glut in domestic natural gas production, existing LNG import terminals were being mothballed and plans for new ones were cancelled. But in early 2016, the Sabine Pass LNG terminal in Texas began exporting LNG, raising hopes for a new market for LNG escort tugs.

To qualify for that work, Capt. Brian has a firefighting system that earned an FFV1 rating. The tug has two remotely controlled FFS fire monitors, each rated at 5,284 gallons per minute. The monitors have adjustable fog tips with foam capability. Two FFS fire pumps are each rated at 5,980 gallons per minute at 185 pounds per square inch. They are powered by two Caterpillar diesels generating 831 hp each.

The tug has a deluge system that envelops the tug in mist as a defense against heat and flames to protect the tug and its crew while fighting a fire on another vessel or on shore.

The tug’s fendering system is also specially designed for safely handling LNG vessels. On the bow, the tug has Shibata cylindrical fendering on top with Viking soft-loop material below. The design lets the tug exert no more than 17 metric tons per square meter of pressure against a ship’s hull. 

A Jason’s cradle (for man-overboard rescues) has been installed to enhance LNG escort capabilities. For the same reason, the boat’s galley can be quickly converted to a medical triage facility.

Given the tug’s versatility, it should be able to handle a wide range of work as markets change or opportunities arise. “If you’re building a boat, you try to make it as functional as possible,” Costa said.

In addition to being the most powerful escort tug in McAllister’s fleet, Capt. Brian A. McAllister will also be its first powered by Tier 4 diesel engines. The two Caterpillar 3516E engines will each generate 3,386 bhp at 1,800 rpm. They will power two Schottel SRP4000 FP thrusters with four-blade 2,800-mm nibral props in nozzles. Bollard pull is 80 metric tons.

McAllister and Jensen Maritime Consultants have a long working relationship. Jensen designed two 96-footers for McAllister, the sister vessels Buckley McAllister and Eric McAllister, which entered service in 2014.

McAllister stayed with the Jensen design for several reasons. One is the hull shape. Some competing designs rely on skegs to enhance escorting capabilities. Capt. Brian A. McAllister and sister tug Rosemary McAllister will, by contrast, take advantage of their wide beam.

Jensen Maritime Consultants designed Rosemary McAllister, shown here under construction at Horizon Shipbuilding, and sister vessel Capt. Brian A. McAllister. McAllister picked up the option on a third tug in the class, Ava M. McAllister. It will be delivered from Horizon next year.

“We’re relying more on hull shape, greater beam, rather than the skeg,” Costa said. The new 100-foot boats will have a beam of 40 feet, making them 4 feet wider than Buckley and Eric.

Jonathan Parrott, Jensen’s vice president/new design development, said the firm’s super 96-footers were in the 4,000- to 5,000-hp range. Tugs of 6,000 hp and higher necessitated a bigger boat. The super 96s can accommodate 6,000 hp, but their size limits the deck equipment they can carry and the 36-foot beam limits the size of the nozzles that can be installed.

Much bigger containerships started calling West Coast ports more than a decade ago. Jensen responded to the need for bigger tugs with its 100-foot-long, 40-foot-beam Valor class design. “That seemed to be where a lot of people were headed,” Parrott said, noting that the extra beam provides significantly more indirect force for steering and braking.

The new McAllister boats are different in appearance from the earlier 100-footers Jensen designed for West Coast operators, notably in their distinctive upright plumb bows.

To meet EPA Tier 4 standards, the new McAllister boat will have an SCR (selective catalytic reduction) system using urea injection to control stack emissions. The urea is injected into the exhaust stream, not into the engine itself.

“We kept finding out little peculiarities of the urea system,” Parrott said.

One of them was its corrosiveness. Jensen determined that using a normal steel tank with an interior coating would not do. In addition to being corrosive, urea is slippery and will seep through even the smallest cracks. “Any microscopic hole and it is going to leak out,” Parrott said. Jensen specified a 2,500-gallon stainless steel tank that allows inspection for leaks along all the tank’s surfaces.

Urea degrades at higher temperatures, and McAllister and Jensen put the urea tank in a separate air-conditioned space inside the engine room to counteract this problem. Cooling urea keeps it “fresh,” ensuring the emissions control system functions properly and prevents spoilage.

Previously, engine manufacturers tinkered with engine timing to meet emissions standards, particularly when moving from Tier 2 to Tier 3. With Tier 4, engine timing returns to settings that optimize fuel consumption. “You’re back to a normal engine,” Costa said. “The reduction in fuel cost will pay for the urea. You’re not penalized for doing Tier 4.”

Schottel SRP4000 FP thrusters before installation.

Schottel redesigned the z-drives on the new tugs to increase efficiency. The nozzles have been opened up a bit where the water exits and made a little longer. The props have been given “a tremendous amount of shape,” Costa said. The result should be a 3 percent increase in efficiency.

The hull paint from PPG is expected to last 15 years. “We’ve been upgrading the painting system,” Costa said. “We don’t want to repaint two or three times a year.”

Crew comfort concerns played a big role in the design. Normally crew will be four to five: captain, mate, engineer and one or two deck hands. The new boats have four crew cabins: three doubles and one single. That means that when the tug is operating with a crew of four, each person would have his or her own space. The boat has a full galley. The adjoining mess/lounge is an open and spacious L-shaped area made possible by the boat’s wide beam.

To isolate noise emanating from the engine room, bulkheads were lined with 4.5-inch-thick mineral wool insulation panels with a lead sheet embedded inside. “It goes all the way around the engine room,” Costa said. “It keeps the heat in here. It keeps the noise in here.”

One noise-reduction element is the drive room containing the three generators located aft of the engine room. This places machinery that runs when the vessel is tied up in a separate space, as far as possible from areas crew would occupy when off duty.

The tug’s larger size also allowed the designers to use straight shafts instead of cardan shafts to connect the engines to the thrusters. Straight shafts create less noise and vibration.

Capt. Brian A. McAllister and Rosemary McAllister are tugboats, of course, not cruise ships. Still, Parrot said, “We’re very much aware how important crew comfort is.”

Or as Costa observed, “This boat is going to be very comfortable, crew-wise.”

Highlights: Most powerful tugs in McAllister’s fleet • First Tier 4 tractor tug working on East Coast • Urea stored in climate-controlled area
By Professional Mariner Staff