Crowley Maritime, focusing its current building efforts on expansion and modernization of its West Coast tank barge fleet, is engaged in a $250 million construction program involving six new heated oil barges and matching 9,000 hp tugs with articulated connection systems.
The first of these six units, delivered from the VT Halter Marine shipyard in Mississippi, was christened in April and immediately set to work delivering petroleum products from Gulf Coast refineries to West Coast terminals, particularly those in southern California. Others will follow over the next year or two. The new tug, Pacific Reliance, and the 180,000 barrel barge, 650-1, are actually the fifth articulated tug-barge unit put into service by Crowley in recent years. Four other units, with slightly smaller barges, were introduced in 2002 and 2003. The tugs and barges are gradually getting larger, more powerful and more modern as the building program continues, according to Ed Schlueter, vice president of Crowley’s subsidiary, Vessel Management Services.
Pacific Reliance, in a class of tugs that are among the most powerful in the United States, is a SOLAS-rated vessel powered by a pair of 12-cylinder, 3612-B Caterpillar diesels with electronic controls and electronic fuel injection. Each engine produces 4,640 hp at 900 rpm, according to Crowley. Those big diesels are coupled to Reintjes gears with built-in shaft brakes. The steel shafts turn a pair of Rolls-Royce 12-foot diameter, five-bladed, skewed-tip propellers with oversize rudders. Although similar to its predecessors, this new tug has enhanced soundproofing and accommodations for a seven-person crew plus the latest in electronic navigation, control and alarm systems.
This tug also marks the first use of an improved Intercon coupler system which allows the tug to rotate the two pins which project out from the side of the hull so the tug remains connected to its barge, but can still move up and down in the notch as the barge changes draft during loading or unloading. With this modified system designed especially for offshore mooring and lightering situations, the tugs crew can rotate the toothed helmets at the end of the 50-inch Intercon pins to a vertical position. In this 90° rotated position, the helmet teeth do not mesh with the matching teeth in the barge notch, but the smooth facing of the pins is still engaged in the steel ‘ladder’ to lock the vessel into the barge notch.
“This type of system is only for loading or unloading in an offshore situation where you don’t want to become disconnected from your barge but you do want to be able to move vertically,” said Schlueter.
The most significant improvements to these units, however, have been made to the double-hull barges that are also being built by VT Halter Marine Inc. Not only are the barges about 30,000 barrels larger but they are set up with a double anchoring system, complete independence of 14 heated cargo tanks, dual-mode inert gas system and a constant-flow ballast exchange system that minimizes the risk of environmental damage potentially related to ballast water.
The barges are also equipped with their own inert-gas generation system and a complete array of Intercon electric deck winches set up for Spectra-style rope for mooring lines.
The dual anchoring system is necessary for the barge to load or unload cargo at offshore mooring systems off the California coast, according to Schlueter. Those mooring systems often require a vessel to deploy both anchors and then fall back on a fixed mooring to stabilize its stern.
Pacific Reliance was completed under a three-year charter agreement with ConocoPhillips that will likely employ the use of those three-point mooring systems, according to Marine Transport Corp., the Crowley subsidiary that operates these articulated tug-barge units.
While most barges have Danforth-style anchors mounted on a slide at the bow, the new Crowley barges all have ship-like anchors deployed from hawsepipes at the bow with all-chain rodes stored in a chain locker.
In keeping with its mission of carrying mixed cargoes of petroleum products or ‘easy’ chemicals, the barge is set up with a devoted deep-well cargo pump for each tank with complete isolation of each of the 14 tanks. Previous barges built in this series, by comparison, have 12 unheated cargo tanks with four individual cargo pump systems.
The newest barge is set up for heated cargo in individual tanks with heating conducted through Trantor plate heaters instead of the more conventional steel coil system.
Pacific Reliance may also be one of the first U.S. tank vessels to employ a constant exchange ballast water system that constantly pumps ballast in and out of tanks to prevent long-distance transportation of seawater.
“This system enables the full exchange of ballast while still at sea,” said Schlueter. “So if you arrive at a place like San Francisco or Seattle, you don’t have the problem of how to handle all that ballast water that you might have picked up in a far-away place. It’s a system that makes the environmentalists happy.”
The ballast system, which can be remotely operated, involves pumping ballast water in while the vessel is still offshore and moving through the water, allowing it to overflow through a system venting through the barge side.
The maritime industry has struggled for years to come up with a solution to the problem of ‘invasive’ species of aquatic creatures being introduced to ports around the world through in-port exchange of ballast water. Some other shipboard technologies being investigated and developed to solve the problem include filtration and separation of ballast water, chemical dosing, ultraviolet light disinfection and thermal treatment.
Pacific Reliance, with tankage for 160,000 gallons of fuel, is expected to be able to maintain a steady 12 knots while pushing a loaded barge in up to a Force 5 sea condition, according to design specifications.
The next tug to follow in the series, Gulf Reliance, will be larger at 135 feet and will be set up almost identically to Pacific Reliance. The next four, however, will be powered by Wartsilla heavy-fuel diesels with slightly greater horsepower and greater fuel oil tankage.
“With fuel prices going up and up, we have come to the conclusion we should do something to counteract that trend by switching to heavy fuel, which is dramatically less expensive than regular diesel fuel,” explained Schlueter. “Those tugs are being set up to burn IFO 380 fuel, which has higher viscosity and somewhat different content,” he said.
Although there are differences in size and machinery between some of the Crowley ATB units, the company expects that when the current building program is complete, perhaps in 2008, units of all 10 pairs will be interchangeable.
None of the tugs are equipped with towing winches since they are designed to remain almost permanently in the notch of their respective barges. When underway, each tug maintains an emergency towline attached to one of the stern quarters of its barge, while an emergency towline rigged from the barge bow can be deployed manually or picked up by a tug coming alongside when bad weather moderates. Meanwhile, should a tug have to break out of a notch because of adverse weather conditions, one strategy is to initially tow the barge by its stern quarter until help arrives or until conditions warrant a change in strategy.
Crowley Maritime is a private company that operates more than 300 vessels, more than 4,000 employees and annual revenue in excess of $1 billion.