Deep-draft Crescent Towing tugs have power to spareJun 29, 2016 02:58 PM
Crescent Towing’s 5,500-hp z-drive tractor tug Mardi Gras pushing downriver on the Mississippi River with New Orleans in the background.
For Crescent Towing of New Orleans, Mardi Gras came twice this year.
The company accepted delivery of the 92-foot azimuth stern drive tugboat Mardi Gras in March, about a month after New Orleans celebrated the annual Fat Tuesday transition into Lent. Jensen Maritime Consultants of Seattle designed the vessel, and Steiner Shipyard in Bayou La Batre, Ala., built it.
Mardi Gras is the fourth ASD tug Jensen designed for Crescent Towing. Steiner will deliver a fifth tug, Arkansas, later this year. “And we have a third boat started at Steiner that should be completed by the end of the year,” said Keith Kettenring, Crescent Towing’s executive vice president.
Capt. Joseph Carson at the sticks. Jensen Maritime Consultants designed Mardi Gras and Steiner Shipyard built the tug.
At 92 by 38 by 19.5 feet, the new vessels are the same dimensions as Lisa Cooper, J.K. McLean and David Cooper, the first three Jensen-designed vessels delivered between 2010 and 2012 from C&G Boat Works of Mobile, Ala. The new tugs are powered with two eight-cylinder Tier 3 engines rated at 2,748 hp each, whereas the previous three are fitted with six-cylinder mains producing 5,225 total hp. All five tugs have Rolls-Royce 255 z-drives.
“We wanted to increase the horsepower and accommodate a 2800-mm propeller on the outdrives to increase our overall bollard pull,” Kettenring said. Higher horsepower and larger wheels in type 19A nozzles boosted bollard pull from 65 tons to 75 tons.
Given the ever-increasing size, tonnage and draft of the ships calling at Crescent Towing ports in New Orleans, Mobile and Savannah, the tugs’ high horsepower and deep-draft design is important for safety and long-term serviceability.
Mardi Gras’ stern has a Washington Crane RSRH, an 80-ton quick release hook and a JonRie 424 hydraulic capstan.
“Horsepower is needed to better control these ships in order to avoid accidents and environmental casualties,” he said.
Once all three of the new tugs are delivered, there will be nine z-drive tugs in Crescent’s 28-vessel fleet. Crescent Towing, a Cooper T. Smith company, chose GE mains for all but one of its ASD tugs — the six-cylinder units for fuel efficiency and the eight-cylinder units for efficiency with a little more horsepower.
Low maintenance is a big plus with the GE engines, according to Larry Ohler, port engineer for Crescent Towing. “They are very dependable engines and there is very little down time.”
One of two GE L250 Tier 3 main engines aboard Mardi Gras producing 2,748 horsepower each.
Kettenring agrees, saying the mains are a perfect fit for the company.
The position of the towing staple on the bow is another departure from the tugs delivered in 2010. Locating it 6.5 feet further back from its spot on the previous tugs changed the vessel’s center of gravity when towing. The modification improved the steering by 30 percent and increased the vessel’s stability. Balancing tankage to increase stability was another modification.
“We worked directly with Jensen on the changes and a big change was the way the shipyard and Jensen worked together to cut the steel,” Ohler said. As a result, Steiner cut 20-foot steel sheets instead of 10-foot sheets, achieving a stronger tug with a smoother appearance. “These boats will be around for 50 years plus because there are fewer welds,” said Ohler.
Chief engineer Jamie Ortiz at the main engine control panel.
“And they are more robust because there are fewer seams,” added Kettenring.
The bow is typically the working end of an ASD tug, hence the natural home of the towing winch — in this case, a JonRie InterTech Series 230 escort winch.
“The JonRie Series 230 is a super series, having a larger brake and more drum capacity to handle larger ships,” said Brandon Durar of JonRie InterTech. The winch incorporates JonRie’s foot pedal control, automatic tension system and active heave compensation.
Chief engineer Jamie Ortiz, Capt. Joseph Carson and deck hands Andrew Carson and Keith Lowe aboard Crescent Towing’s Mardi Gras.
“The controls are all JonRie in-house design along with the 60-hp HPU, which also operates the JonRie series 424 hydraulic capstan aft,” he added.
On the aft deck is a JonRie 424 hydraulic capstan and a Washington Chain RSRH rotary quick-release hook. The stern equipment is used for lighter work, smaller tows and vessel shifting.
“We also increased the size of the drum on the JonRie winch to take 550 feet of 9-inch Plasma line,” said Ohler. He added that they increased the brake tension to 350,000 pounds to accommodate additional steering forces caused by the relocated staple.
Mardi Gras has a JonRie Series 230 escort winch on deck with 550 feet of 9-inch synthetic line.
Firefighting is provided by a SKUM monitor supplied with 4,200 gpm of water by a Peerless pump powered by a John Deere model 6135AFM85 engine.
Schuyler Companies supplied the cylindrical fender to wrap the curve of the bow bulwark. Below the bow fender, a section of Model 100A laminated fendering protects the lower section of the bow and the forward end of the skeg. The sides and stern are covered with D-Obore fendering and aircraft tires to provide extra cushion.
Crescent Towing’s fleet shuffle will see the new Mardi Gras replace Port Allen, while the original Mardi Gras has been renamed Port Allen.
When the three new tugs are delivered, Crescent will spread its nine z-drives among its three ports. The 98-foot, 6,700-hp Bulldog and the 96-foot, 4,000-hp Savannah are in Savannah; the 104-foot, 5,200-hp, Point Clear is in New Orleans along with David Cooper and J.K. McLean; and Lisa Cooper is in Mobile. Deployment for Arkansas and the unnamed third tug has been not determined.
“We think that these boats built at Steiner are very well-crafted tugs,” Kettenring said.
“We have bought the design from Jensen,” he added, “so we think this is going to be the future tug design for us.”