New Boston boat advances the art of tugboating

Half of its fleet may have been inactive during the worst of the recession, but that has not stopped Boston Towing & Transportation from locking up its position as the lead tugboat company in its port, as symbolized by the recent arrival of its latest tractor-style tugs.

(Brian Gauvin photos)

The two tugs, Independence, 128 feet and 5,400 hp, and Justice, 98 feet, 5,400 hp, are largely dedicated to the newly-constructed offshore LNG importation terminal located about 10 miles outside of nearby Gloucester, Mass. The company, and these two tugs, are under long-term contract with Neptune LNG, an affiliate of Suez LNG North America. Boston Towing’s two other ASD tractors, Freedom and Liberty, were purpose-built in 2003 for assisting LNG tankers making their way into unloading facilities within the harbor.

Independence heads home after unloading cargo, including transferring crewmembers, to an LNG tanker moored about 10 miles outside of Gloucester, Mass.

“If you want to be the premier tugboat company in Boston, you’ve got to have the LNG contracts, and it looks like that’s what has happened,†said Vincent (Jake) Tibbetts, president of this 75-year-old company, now a subsidiary of the Reinauer Transportation Companies of New York.

The other sizeable tugboat company in Boston is Constellation Maritime, a subsidiary of Foss Maritime, with its green and white tugs, including at least one tractor tug, tied up almost directly across the inner harbor from those of Boston Towing.

While conventional LNG tankers continue to unload at shore facilities such as those inside the port of Boston and at a half dozen other U.S. terminals, the newest breed of offshore tankers are specifically designed to re-gasify their own cargo and to offload at offshore mooring terminals (buoys), several of which are now available outside Cape Ann, Mass. LNG tankers were already calling at the new Neptune floating terminals this past spring, with practice loads, while regular shipments are expected to commence later this year. The facility consists of a deep-water buoyage system, with two floating pipeline buoys, and a 13-mile submerged pipeline connected onshore to the Spectra Energy pipeline, which facilitates delivery of gas to New England customers.

Independence Capt. Chuck Delory keeps an eye on the tugs position while standing by at an offshore LNG terminal near Boston.

The mission of Boston Towing and its tugs is to provide ship-assist service whenever needed, plus offshore logistics and support, towing, firefighting, man-overboard assistance and to provide general service as needed, with at least one tug always on standby duty on site when a ship is at the terminal, according to Bill Skinner, marine superintendent of the tug company.

“We also need to be ready to assist in preventing other vessels from entering the Coast Guard-established security zone,†he added.

Bill Skinner, marine superintendent, left, and Vincent Tibbetts, president of Boston Towing & Transportation, during a quality-control ride aboard their new tug, Independence.

Independence, the larger of the two new tugs, is based in Gloucester, closer to the offshore site, while the smaller tug, Justice, is based in Boston and is free to work at general shipdocking assignments when not needed for LNG support work. Independence is involved in daily support activities on a year-round basis whenever a ship is at the terminal. As part of that service, the tug can self-load and transport three containers and other supplies on its aft deck, in addition to transporting crewmembers and passengers. As part of its design for year-round work, Independence features a massive and voluminous hull with sponsons for added stability on both sides, raised forward bulwarks, a relatively low profile, 21 heated pilothouse windows, heated decks and cap rails and a long list of equipment for general offshore capability. On-deck equipment that appears immediately to the eye are the Effer deck crane, Ribcraft rescue boat, full-boat deluge system, JonRie InterTech towing winch and the Markey hawser winch.

A relatively unusual feature that cannot be seen is the controllable pitch (CP) propeller package that immediately added a new dimension to both maneuvering and technique for firefighting.

Propellers in a CP system can be ‘feathered’ over a substantial angular range with consequent reduction in needed engine power with each angular reduction. Thus, with propeller(s) partially feathered there is engine power available to operate a fire pump directly off the front end of each engine after being engaged by an electro-hydraulic clutch. While the pump is operating, however, the partially feathered propeller can still be used to move the tug.

Skinner, of Boston Towing, estimates that running a fire pump flat out might take up to 1,000 hp out of each engine, thus leaving considerable power still available for driving and maneuvering the tug.

While the CP props were originally designed to facilitate firefighting efficiency, the tug’s crew immediately took to the feature as an added control dimension for underway operations. Charles “Chuck” Delory, one of the tug’s captains, said the CP props remind him of a diesel-electric propulsion system, where he can leave the engine running at a modest rpm and use the CP feature to control boat speed, thrust and even reverse direction since propeller pitch can be reversed as well.

The main engines are 16V-4000 M-61 MTU diesels connected by carbon fiber shafts to Rolls-Royce 255-CP drives. The engines produce 2,700 hp each at 1,800 rpm, according to tug specifications.

Another design feature that is not readily discernible is the use of steel sponsons on either side of the hull to provide greater buoyancy.

The hull of Independence flares out just below deck level, thus allowing the tug to be built with a narrower hull in way of the waterline and further below. The sponsons provide for a larger deck area without a matching increase in displacement, said Skinner. The tug thus has the same waterline length and beam, without the added drag and associated fuel consumption, he added.

The tug’s designer, Robert Allan, explained that the sponsons, with their inherent buoyancy, were initially designed to provide enhanced escort capability, but they also function as unofficial roll dampening devises, he said.

Also, about that hull, counter to many new tractor-style tugs these days, Independence does not have an escort keel. Instead of a short, deep keel, situated at the forward end, this tug has a long, full keel located more or less amidships. The actual keel is about 80 feet long, three feet wide at its base and roughly five feet high, according to Skinner.

“This tug is not intended to do formal escorting,†said Skinner, “and we wanted to achieve other advantages with the long keel.†Specifically, he said, the long keel provides better tracking offshore and makes for easier dry docking. In addition, he said, a keel with lots of surface area also helps to reduce roll when working offshore for long periods.

Independence is designed to remain offshore at the Neptune terminal possibly for days, or considerably longer, during periods of heavy activity. Because LNG carriers working at offshore terminals first have to re-gasify the liquid cargo before pumping it overboard, it can take days to unload. During that time at least one of the new Boston tractors is expected to remain on station.

By Professional Mariner Staff