Pacific Maritime Magazine - Marine Business for the Operations Sector

M/V Samish: Washington's Second Olympic Class Ferry

 

The second Olympic-class ferry M/V Samish, was delivered last month to Washington State Ferries by a consortium of builders including Vigor Fab, Nichols Bros. and Jesse Engineering. Photo courtesy of Vigor.

The commissioning of the M/V Samish in the Washington State Ferries (WSF) fleet marks another milestone in the agency's plan to replace the three vessels in the 310-foot Evergreen State-class, built between 1954 and 1959, before they are 60 years old. The new Olympic-class vessels are 362.5 feet long with an 83-foot beam and carry 144 cars. This is a "mid-size" ferry for WSF; the first, M/V Tokitae, is in service on the Mukilteo-Clinton run, the second will join the Anacortes-San Juan Islands route at the start of the Summer 2015 sailing season on June 14.

The design for the Olympics actually dates back to 2007. Seattle naval architects Guido Perla Associates were preparing the vessel design when severe hull corrosion was found in four of the system's smaller ferries – the 60-car Steel Electric-class built in 1927. The Olympic design was shelved until early 2012, after the legislature approved $265 million for construction of two vessels. Guido Perla reprised the general plans and performed detailed engineering to enable the consortium that had successfully built the three 64-car vehicle ferries in 2009-2012 to begin work. (To comply with a 1993 state law, all Washington State ferries have to be built in-state.)

The team includes Vigor Fab at Vigor's Seattle yard as the prime contractor, Nichols Brothers on Whidbey Island to pre-fabricate the superstructure and Jesse Engineering in Tacoma to build the two identical bows. Other partners were Eltech Electric for the electric systems and controls, and Greer Tank & Welding. WSF supplied its standard propulsion package of twin Tier 3 EMD medium-speed two-stroke diesel engines originally purchased through Valley Power Systems.

The engines produce a maximum of 3,000 HP at 900 rpm.

In the double-ended hull, the engines face in opposite directions, each connected to one Rolls Royce controllable-pitch four-blade propeller via a Falk 4.986:1 reduction gear. To improve the steering, Rolls Royce high-lift rudders were fitted at both ends of the vessel. An inter-connecting shaft runs between the two transmissions, allowing both engines to power a single aft propeller for a top service speed of 17 knots at 80-percent power, with an economy cruise speed of 14 knots.

Energy efficiency is increased by the waste-heat recovery system that uses the exhaust gases to provide hot water for the ship's hotel needs. There are three MTU Series 60 300kW gensets in the engine rooms with a fourth on the sun deck for emergencies. The navigation and other lights are LEDs.

The double-ended hull is classed Sub-Chapter H for 1,500 passengers by the US Coast Guard. It was assembled from 10 modules with steel plating 7/16-inch thick on the bottom; the superstructure plating is generally 1/4- to 5/16-inch thick. The efficiency of the bow shape was improved by tank tests to feature a more streamlined "wake-adapted" stern shape that required a thin tapered shape for the stern tube and skeg, explained Brian Evert, Vigor Fab's director of project management. This was accomplished with special castings and heavily-rolled plating.

The superstructure of the Olympic-class ferries is more than 300 feet long, weighs 1,500 tons and includes four upper decks: the upper vehicle deck, the passenger deck, sun deck, plus the crew-only navigation deck. To load the massive house onto a barge, heavy lift contractor Omega Morgan laid a platform from Nichols yard 600 feet across the county road, beach, and tide flats out into Holmes Harbor to reach a depth of 12 feet at high tide.

After the tow to Harbor Island in south Seattle, another 600 feet of track had to be laid from the barge to the deck of the bare hull with both in drydocks. The transfer was successfully completed by specialist movers Engineered Heavy Services. The Olympic class features wider lanes, two compliant ADA elevators, stairwells four-feet wide and less angled. Overnight cabins are provided for crew who are working the early shift or re-positioning the ferry.

Rolls Royce high-lift rudders are fitted at both ends of the vessel, and an inter-connecting shaft allows both engines to power a single propeller for a top service speed of 17 knots at 80-percent power. Photo courtesy of Vigor.

In an extreme emergency, there are two Marine Evacuation Systems on each passenger deck housed in large lockers. They inflate to provide an inclined evacuation slide leading into an extra large-capacity SOLAS inflatable liferaft. Four additional rafts are stowed on the sun deck.

The ferry is operated from identical wheelhouses at each end. The helm consists of two jog sticks set fore and aft on the console – one for each rudder. When under way, the forward rudder is automatically locked amidships and the forward CP propeller feathered for minimum resistance.

At very low speed, both rudder and propeller can be activated for docking. In the event of any of these controls mal-functioning, the helmsman also has an electronic order telegraph to signal the engineer on duty in the engine room to over-ride the system manually. The two throttle levers are combined with the propeller pitch control, and all controls have 100-percent redundancy.

 
 

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