New tug simulator will incorporate operating characteristics of winch and line


This digital rendering depicts the way the Energia Costa Azul liquefied natural gas project in Baja California will look upon completion of the marine terminal. The 2,100-foot-long breakwater is designed to protect a one-ship berth. Four escort tugs with a bollard pull of 75 tons are being built in Spain for Moran Towing. MarineSafety International is programming its tug simulator in Newport, R.I., to replicate the operating characteristics of the tugs' winches and lines. (Courtesy Sempra Energy)

As part of a liquefied natural gas terminal project in Baja California, Mexico, the training and research company MarineSafety International is incorporating winch and line data into its simulator training.

In the past, lines were kept at a constant in tug simulation. But bigger sea conditions at the Costa Azul LNG receiving port meant that a special winch had to be engineered so that tugs could bring the LNG carriers into port. MarineSafety International (MSI) is incorporating winch and line data into its model to help train tug captains and the pilots who will dock the LNG carriers at Costa Azul using this new winch.

The simulator will use data from the DESDF-48WF winch, manufactured by Markey Machinery Co. of Seattle, Wash. This is a high-speed, 760-hp double-drum electric hawser winch designed specifically for the Costa Azul project. Cortland Puget Sound Rope in Anacortes, Wash., supplied the data for the lines. The rope company supplied elongation data for its Plasma 12-by-12-strand synthetic rope, a high-strength, low-stretch rope. The rope is manufactured from Honeywell Spectra fiber, which is then enhanced by a recrystallization process at Puget Sound Rope.

MSI, which is based at LaGuardia Airport in New York, runs a ship simulator center in Newport, R.I. The company has been involved both in berth layout research and mariner training for the Costa Azul project for several years. At its ship center, MSI has the staff to build ship simulations, to write the computer code to create simulated training situations, to build and maintain the simulators and to oversee the interaction of all these parts.

"Giving the mariner the actual data that they will be expecting to see when they are using the actual winch increases the value and validity of the training and gives the mariner confidence and familiarity in the equipment they will be using," said Rick Comeau, an instructor with MSI.

The need for a simulator with winch and tug data came about as a result of Sempra LNG's $945 million Energia Costa Azul LNG receiving terminal. The new terminal is scheduled to begin operations the second quarter of 2008, according to Art Larson, spokesman for Sempra Energy of San Diego, Calif., which is overseeing the construction of the terminal.

When operating, this will be the first LNG receiving terminal on the North American West Coast, processing one billion cubic feet of natural gas per day. LNG carriers capable of carrying between 138,000 and 210,000 cubic meters of gas will dock at this terminal. A 2,100-foot-long breakwater is being constructed to shelter the single-ship berth from Pacific Ocean swells, according to the Energía Costa Azul Web site.

Four new FiFi-1 escort tugs with bollard pull of 75 tons have been designed for the project by Robert Allan Ltd. They are being built at the Union Naval Shipyard in Valencia, Spain, for Moran Towing Corp. of New Canaan, Conn. Moran won the contract to provide tug services and ship assist expertise for the new terminal.

MarineSafety International began working on berth layout research for the Costa Azul project about three years ago, when it had a San Diego office (which since closed), said Rick Comeau. Sempra worked extensively with MSI on the marine aspects of mooring LNG carriers at Costa Azul, according to Larson. Right now, Sempra is training mariners at MSI to dock and undock LNG carriers at Costa Azul under a variety of conditions. That training is already occurring, even though the dedicated tug simulator is not finished. MSI's staff can come up with new ship simulation and port models as required; it has the data for over 250 ships in its computer banks.

This data for the Costa Azul LNG terminal will all be plugged into a new, dedicated tug simulator, scheduled to be finished in March, Comeau said.

The simulator will be able to accept controls for several different winches, all made by Markey Machinery: a ship-assist towing winch, an open-ocean tug winch and a winch that is similar to the unique winch Markey is building for the four Moran tugs that will operate at Costa Azul.

MSI is using the controls and data from Markey's DESF-48 winch, which will be ready for use on the simulator in mid-March. Comeau said MSI plans to incorporate data from the Costa Azul winch later, but that cannot be done now because the new winch has not yet been built.

The crucial part of the new tug is the new electric render-recover winch being designed and built by Markey. The new winch is necessary because outside the breakwater there could be 3-meter seas every 10 seconds, according to Scott Kreis, Markey's sales manager. Under these conditions, it is crucial to maintain positive tension in the line between the tug and the LNG vessel at all times.

The Costa Azul escort tugs will be equipped with DESDF-48WF winches from Markey Machinery. These high-speed 760-hp double-drum electric hawser winches were designed specifically for the conditions that prevail at the Costa Azul terminal. Puget Sound Rope is supplying the Plasma lines. (Courtesy Markey Machinery)

"The dynamic loads created when you're handling ships in these conditions, are significantly greater," said Barry Griffin, of Griffin & Associates, of Bainbridge, Wash., a manufacturer's representative for Markey. "The potential shock loads that can occur in the rope because of the tug bouncing around is much greater when in an offshore condition," Griffin said. "Under a shock-load situation offshore," the tug could lose connection with the vessel. In addition to lines breaking, bitts and chocks on the LNG vessel could be ripped out if a surge load occurred, said Comeau.

A year ago, Markey began doing numerical modeling of the Costa Azul port to see how much horsepower was needed in the winch, according to Blaine Dempke, Markey's president. Defining the line-loading forces that the terminal's tugs and deck machinery would need to handle required Markey to perform over 300 hours of simulations, engineering analysis and scale-model tank testing.

After the modeling, Markey came up with a design for the DESDF-48WF. It uses render-recovery technology to minimize the effects of forces and motions induced by high seas.

The winch features two drums, each with about 650 feet of 10-inch circumference soft-line in seven-plus levels. A single automatic level wind serves both drums.

The render-recovery technology means the winch maintains constant line tension and automatically compensates for the tug's surge, pitch and heave. "The winch takes care of tension and prevents the line tension from getting too high," said Griffin. "It provides for safe operations up to the full performance of the tug."

The winch controls tension and keeps slack out of the working line at all times, preventing snap-loads from occurring and reducing the risk of lines breaking or damaging the bitts the line is secured to on the LNG tanker. The DESDF-48WF hawser winch can maintain constant line tensions up to 75 metric tons in 1-meter seas and 63 metric tons in 3-meter seas.

There is a digital display that shows line speed, line tension and scope-out feedback for the winch. But there is also an analog display that shows line tension in a manner that is easier to read, said Comeau. In addition, there is a tension display for the pilot on the LNG tanker, allowing the pilot to observe tension in each of the four tugs' main lines, in real time.

The most difficult part of adding the winch to the simulator was the calculations needed. "Making the mathematical models work properly is the biggest challenge," said Comeau.

"This winch has features to it that most winches don't have, that we have to figure out how to apply to the simulator."

Once the new tugs are operating, a black box will be placed in one of the tugs, to collect data, "so we can go back with real-world data to compare with our numerical modeling," said Dempke.

And MSI will be interested in that real-world data, so they can compare it to the simulator. "We may have to tweak it a little," said Comeau.

Small factors could impact winch performance compared to the simulator model. For example, the Costa Azul winch is so sensitive that the speed rate of the spool is impacted by how much line is released.

By Professional Mariner Staff