Next Tug for Tidewater: Granite Point


Photo courtesy of Vigor.

Tidewater's second new push tug, the Granite Point, was launched at the Vigor Industrial shipyard in Portland in late September.

Tidewater Transportation and Terminals' series of three new towboats is continuing on schedule with the launch on September 18 of the second of the class, the Granite Point, at the Vigor Shipyard in Portland. This was less than three months after the christening of the first of the class, the Crown Point, while the hull of the third and final vessel, the Ryan Point, is already complete and the superstructure modules are being fitted out before assembly. These are the first new vessels to be built for Tidewater in 30 years, and mark a significant technical step for Vigor, Tidewater and the Columbia-Snake River system in general.

Headquartered in Vancouver, Washington, Tidewater operates a fleet of 16 vessels and 160 barges to transport a wide range of cargo among a network of upstream ports, terminals and grain elevators reaching 350 miles to Lewiston, Idaho. The new design takes advantage of numerous technical developments to significantly improve fuel efficiency, reduce exhaust emissions, and increase crew safety and comfort with the latest sound and vibration reduction measures.

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Tidewater chose CT Marine, Naval Architects and Marine Engineers of Edgecomb, Maine to design the class. Founded by Corning Townsend in 1978, this office specializes in riverboat and ATB design and has an outstanding record, with many design innovations, more than 200 vessels from 500 to 10,000 bhp at work on American rivers, and another 25 under construction this year alone. However, it was only when Townsend visited Tidewater and rode a tug and barge tow through the Columbia Gorge that he experienced the high winds and currents and truly appreciated the difficulty of navigating the locks and narrow channel.

"That trip showed me that the conditions on the Columbia River were very different from the Mississippi and called for an entirely different type of boat," he told me. "Turning power and thrust were of paramount importance, but even the deck layout is different. With reduced draft restrictions, the four empty barges had a higher freeboard of as much as 15 feet, compared to 10 feet in the mid-west. That increased the windage and difficulty of turning," he explained. When he returned to Maine, he went back to the drawing board, and produced a new concept that he felt would meet all these demands.

For superior handling, he specified an enhanced steering system using four steering and four flanking rudders. "Fitting twin rudders on each nozzle increases the side force by at least 30 percent, and allows shaft removal with the rudders in place," Townsend pointed out. To increase visibility, he drew the wheelhouse with exceptional all-round visibility through full height windows and a split steering console. He also changed the bow from the traditional scow-type to a ship-type with a heavy stem to divert logs towards the side and away from the propellers. This was a feature that he had tested in the NRC model basin at St. John's, Newfoundland and used successfully on Corps of Engineers boats on the Mississippi.

CT Marine succeeded in packing all the required equipment, 44,000 gallons fuel and two Caterpillar 2,240 bhp engines into a compact 102-foot by 38-foot vessel that met all Tidewater's expectations. When the Vigor Shipyard in Portland was chosen as the builder, Tidewater's engineering team began refining the design with Vigor's production engineers and Genoa Design International Ltd. (GDI) of Newfoundland, who performed all the 3D modeling, lofting, CAD files, and detail design. "We developed an excellent working relationship with Tidewater staff, and were able to improve on many details and streamline the building procedure," stated Kale Kramer, Vigor's director of manufacturing."

Kramer flew out to eastern Canada to visit GDI and ensure the changes were all integrated into the final design before any plate was CNC cut in Portland.

"A great deal of effort went into designing, engineering and building a towboat that would meet or exceed all performance parameters," commented Bruce Reed, Tidewater COO and Vice President. (GDI is involved in many high-profile projects including New York's Staten Island ferries and is a part of Canada's National Shipbuilding Strategy, providing services to the Vancouver BC Shipyard building new offshore research vessels.)

Tidewater's three sister ships are environmentally friendly vessels with EPA Tier 3 compliant V-16 diesel engines driving two 92-inch by 100-inch fixed pitch, stainless steel propellers through CT's own SL-type Kort nozzle, via Reintjes (WF 873) 6:4.41 reduction gears. The stern above the screws is slightly concave, creating a small "tunnel" effect; the service speed is 8 knots with sufficient fuel for two round trips to the upper Snake River. To minimize power usage, variable-frequency drives were used in all major rotating machinery applications and LED lighting was employed throughout. The deck machinery consists of seven Patterson WWP 65E-7.5, 65-ton electric winches, with pilothouse remote operation and local push button control stations on the main deck. Each winch has Samson 1 3/8" Turbo 75 Synthetic Line.

Tidewater also went the extra mile to ensure the crew areas had the best-possible technology to reduce noise and vibration. They employed Noise Control Engineers of Billerica Massachusetts to develop a sound and vibration control package for the vessel, Reed explained. In the engine room, this effort began with Christie and Grey vibration-control engine mounts and comprehensive acoustic insulation of the bulkheads with vibration damping tiles. Particular attention was paid to the elevated mufflers, which are heavily insulated and flexibly mounted where they pass through two openings in the overhead deck above the engine room.

The generator room is positioned aft on the main deck as far from the accommodation as possible and with soundproof doors to contain the noise of the two Cat 7.1, Tier-3 480-volt generators, rated at 200 kW at 1,800 rpm. The insulation measures focus on the crew quarters where they are supplemented by a floating floor inside the entire forward half of the deckhouse. Each space is effectively a freestanding insulated box surrounded by an 8-inch space filled with specific insulating materials in the walls and overheads. There are soundproof doors at both ends of the central corridor leading from the mechanical areas aft to the galley, creating a double barrier.

The livability of crew spaces is growing in importance to attract and retain crew and increase safety. Tidewater Port captain Brian Fletcher proudly pointed out that this unprecedented effort has resulted in noise levels of less than 60 decibels in the accommodations during vessel operation. The captain and mate's staterooms on the upper deck benefit from the same acoustic treatment and are even quieter.

Photo courtesy of Vigor.

The new Granite Point's flat-bottomed hull has strengthened bow plating to withstand impacts from logs and flotsam.


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