Evolving winch and vessel designs enhance towing safetyJun 1, 2011 12:00 AM
There have been numerous innovations in winch towing operations over the past few years — render-recover winches, auto-abort systems, independently powered level-wind systems, digital line tension displays in the pilothouse — but all this new technology means that good training is even more important.
"Winch manufacturers are designing equipment that we didn't even ask for five years ago," said tug safety consultant Capt. Gregory Brooks, president of Towing Solutions of Spring Hill, Fla. This is "very sophisticated equipment that allows us to do our job more safely."
Without a proper understanding of the new equipment, "you can get into trouble because you think it will do something that it won't," said Brooks. In most cases, comprehensive training is done. But sometimes the ball gets dropped between the president of the towing company, who is paying a lot more for the winch, and the captain, who is driving the boat, Brooks said. â€œIf you pay the extra money for the winch, you should ensure that you train your people so that you can reap the benefits of the machine."
Boston Towing & Transportation's ASD tug Independence (designed by Robert Allan Ltd., of Vancouver, British Columbia) has large windows facing aft, affording the crew in the pilothouse good views of the deck and the JonRie InterTech Series 525 towing winch. (Brian Gauvin photo)
Jonathan Parrott, vice president of new design development at Jensen Maritime Consultants, agrees. "It is crucial for the winch manufacturers to be on hand for these training sessions," Parrott said. "The winches coming out now are incredibly complicated and fairly smart machines. The winch guys have to let (them) know what the winches can and cannot do."
David A. Beardsley, vice president of construction and repair at Moran Towing Corp., said that when a new winch is delivered, the manufacturer's representative is on board the tug for the first job to help train the crew.
The increased sophistication of winches means that a crewmember spends less time on deck as the tow and winch operations are monitored and controlled from the pilothouse. This places the deck hand in a safer environment, where he or she can also assist the deck officer as part of the bridge team and provide the two-person check.
"All the equipment is becoming more and more user-friendly, and it is all coming up into the wheelhouse to allow for better coordination between crewmembers," said Brooks.
In some cases, such as the big offshore tugs, companies have a second person in the pilothouse to run the winch, following the captain's orders, while the captain drives the boat. "Some of the boats have adopted a kind of offshore style of operations where the chief engineer will come up into the pilothouse and run the winch," said Brooks. This depends on the job, said Brooks, and there are some jobs where the captain can easily run the winch on his own.
With this change, the ability to see the deck and the winch from the pilothouse is even more important. "One of the most critical things on these boats is line of sight," said Parrott. "The guy up on the pilothouse must have a good line of sight everywhere."
This has become more challenging for naval architects, as more powerful winches are being put on smaller tugs. "You're getting smaller deck spaces — they have to compact everything," Parrott said.
The 128-foot tug was built to assist LNG tankers using an offshore terminal near Gloucester, Mass. (Photo courtesy JonRie InterTech / Bobby Davis)
Winches are also getting smaller, with a footprint for the winch that is 20 percent less than what it used to be.
A major change in how tugs are designed has helped with line of sight, and other issues. In the past 10 years, modeling of vessels during the design process has become more and more sophisticated.
"It has become easy to make a 3-D model of the deck and pilothouses," said Parrott. With a 3-D model, you can move the location of the winches around, for example, and then take different camera shots of those winches based on the modeling.
"You can do a fly through and just find out what you can see from the pilothouse," said Parrott. "It gives the owner a really good idea of what the boat looks like before you cut steel. And it helps for placement making sure the deck gear is laid out properly."
The design process should also include more input from those working the tug.
"The winch guy should not be independent from the naval architect — it all should be hooked together," said Brandon Durar, president of JonRie InterTech. "That is how I perceive the future."
Parrott agrees: "We try to get as much feedback from everyone on everything we can," he said.
Another major innovation is the render-recover winch, pioneered by Markey Machinery Co. A winch of this design automatically keeps the line tension constant, without allowing dangerous high line loads or slack conditions. If wave action creates forces that could separate the tug from the tow, the line automatically spools off the winch to prevent overload. And if wave forces bring the tow and the tug toward each other, this controller system quickly retrieves the line to eliminate any slack. These winches are usually powered by electric motors. Real-time line speed and load data are displayed in the pilothouse.
Durar said that the method to display all this information in the pilothouse has evolved. At first, the information was displayed only on computer touch screens. Having to select menus off a touch screen gets complicated, with all that a captain has to do, he said. Particularly in displaying line tension information, "we went back to analog meters," said Durar. "It's like trying something new and going back again."
The winch controls aboard Independence are mounted in the pilothouse. The controls feature independent level wind, which means none of the crew needs to be on deck once the tug has made up to its tow. An emergency abort system, visible in the upper right corner of the photo, activates when the tugâ€™s heel reaches 15 degrees. (Photo courtesy JonRie InterTech / Bobby Davis)
Beardsley said that with all the new alarm and monitoring systems, Moran has made changes in where these displays are located in the pilothouse. Some of the digital controls are so sophisticated that the captain can troubleshoot the winch itself from the pilothouse.
"We've been going through a learning curve as to where to best mount these units," said Beardsley. Some of the digital displays are mounted overhead, above the operator. "If you spend any time with the machine in the overhead position, it becomes tedious — from neck strain to sun glare, or just holding your hand high above your head to use the touch pad screen."
Moran has also found that it helps to have analog meters along with the new, digital displays. For example, Beardsley was on board a boat recently and looked at a touch screen panel for the line tension meter, and he found some of the text hard to read on the small screen. So the company is working to install an analog meter mounted on a window mullion.
"We're trying to put a meter that he can view without looking down or looking up, and taking his eyes completely away from the field of vision," Beardsley said.
Blaine Dempke, president of Markey, said another new feature is data logging in which all the line tension data is stored in a computer, to be reviewed at a later date. Data logging can be used for many purposes. One is to monitor the life of soft line, which is increasingly used instead of wire.
"This is important, because the cost of soft line is so high, that you want to use it as long as you can, but not one day longer," said Dempke.
The use of soft line, in general, has helped with injuries. "You are getting the wire rope off the working deck," said Dempke.
When crews do handle the line, soft line reduces injuries to the hands from the barbs on wire line.
JonRie InterTech has also worked with naval architects on the H-bitts, in order to bring the cross bore as low as possible. "The distance to your screws is lower, and makes the vessel more stable," Durar said.
Another change that helps safety is that crewmembers no longer level wind off the drum.
"Once you have made up the tow, you don't have to go down on the deck anymore," said Durar. "You don't have the extra man down awash having to adjust the level."
JonRie InterTech developed a level winder powered by an independent motor with separate controls that can stop and start the winder to adjust the wire-spooling operation.
Render-recover winches also have a sensitivity control, which dictates how quickly the winch responds to specific sea conditions.
"If you have a short, steep seaway giving you some bumps, you dial the sensitivity up so the winch responds quicker," Brooks said. "But if you have a long, rolling Pacific swell, you can dial that sensitivity down so the winch responds a little more gently — so you're not jerking your own line and creating surge loads on the gear."
Another innovation is electronic abort systems that are controlled in the pilothouse. The abort system releases the winch brake and allows the drive motor to freewheel so that all the line is released from the drum.
Beardsley said Moran is putting abort buttons on deck for the crew, as well as having them in the pilothouse. These systems also have battery backup.
For line tows, abort systems can be set to respond to specific conditions and abort automatically. For example, JonRie InterTech's automatic abort systems include a tug attitude sensor, which monitors the tug's deck edge submersion while escorting and towing.
"Once you hit deck immersion, you should release your tow," said Durar. The captain can still activate the abort system on his own. "But if something happens, and you miss your opportunity, you can auto abort with this sensor."
With the advent of auto abort systems, it is critical to carefully evaluate the factors that trigger them. "The problem with auto abort is, how do you set up the system? What will be your criteria?" said Parrott. "Any time you have an automatic system, you have to step back and look at the parameters and say — are these realistic? It is going to be the human eye, and brain reaction, that are still going to be critical in the whole operation."