WSF develops Olympic class

In late December 2015 Washington State Ferries (WSF) in Washington state in the USA’s Pacific Northwest confirmed an order with shipbuilder Vigor Industrial in Seattle for the fourth vessel in its series of Olympic class passenger and vehicle ferries. Construction work on the new ferry started in January. The vessel, costing US$122 million, is being funded through the state’s Connecting Washington transportation funding scheme and is due to be delivered in mid 2018. The Olympic class ferries have capacity for 144 vehicles and 1,500 passengers. WSF services carry more than 23 million passengers each year.

The new ferries are replacing four old vessels, built in the 1950s and 1960s, to provide more efficient, reliable, environmentally friendly, safer and more comfortable operations. The fourth ferry will follow the earlier three ferries in the class of which two, Tokitae and Samish, are already in service. The latest order follows Washington state legislature approving funding for the fourth ferry in July 2015.

Tokitae has operated on the route between Mukilteo and Clinton since mid 2014. Samish entered service in June 2015 following two months of sea trials and crew training. It serves the Anacortes to San Juan Island route. The third in the series, Chinacum, is under construction and due to be delivered in early 2017. It will operate on the route across Puget Sound between Seattle and Bremerton.

The name of the fourth ferry will be subject to a public consultation process. The names of all the vessels derive from native American languages in the Pacific Northwest.

The new ferries are replacing WSF’s Evergreen State class ferries, most of which were built in the 1950s and modernised in the 1990s. At the time the initial Olympic class contract was placed, 10 of WSF’s 22 passenger-vehicle ferries were between 40 and 60 years old. The four Olympic class ferries will directly replace four of these vintage vessels and it is planned that all 10 will be replaced over a 20 year period.

Following the original design and build contract in 2007, Tokitae was ordered in early 2012 and delivered in June 2014. Construction of the second ferry started in late 2012 and Samish was delivered in April 2015. The original contract between WSF and Vigor provided for construction of up to four ferries. The service has a usual requirement for three ferries, and having four will allow one to be on standby. The new ferries have an expected operating service life of up to 60 years and have been designed with that in mind, taking account of anticipated changes in demand patterns, including population growth and increased demand during peak periods.

WSF chief of staff Elizabeth Kosa commented: “Our top priority is keeping the ferry system safe and reliable for the millions of commuters, freight haulers and travellers who depend on us every year. Thanks to state lawmakers and critical funds from Connecting Washington, we are able to meet some of the ferry system’s most urgent needs, including building this new ferry.”

WSF said that the Olympic class ferries are equipped with the latest emergency evacuation and fire-suppression systems, and have two elevators with improved accessibility that comply with current legislation. The vessels’ hull design reduces wake and provides better fuel efficiency, while cleaner burning engines reduce emissions using low emission fuels, and offer reduced risk of fuel spills, and reduced engine noise and vibration. The basic design, by Guido Perla & Associates, is an updated version of WSF’s successful Issaquah class ferries, which have capacity for 130 vehicles.

WSF communications manager Brian Mannion told Passenger Ship Technology: “Our top priority is to provide safe, reliable transportation across Washington’s ferry system. New vessels help us do this by allowing us to retire the oldest vessels, which are 60 years old or more. New vessels provide greater reliability and the benefits of updated technology, including better fuel economy, smaller wake, cleaner burning engines and increased passenger comfort. In addition, retiring the older vessels allows us to focus our limited maintenance time and money on vessels that are in better shape. Our crews do an amazing job maintaining our fleet, but the reality is we get more bang for the buck when we invest in keeping a newer vessel in great shape, rather than trying to coax along a machine from the 1950s.”

The Olympic class ferries are double ended with five decks. There are two vehicle decks, a main passenger deck, a sun deck, and a navigation bridge deck. The vessels have improved heating and ventilation, and more internal flexible seating to improve passenger comfort. The design includes slightly increased vehicle capacity for cars and trucks with wider car deck lanes that provide more room for passengers to access their vehicles.

The main sub-contractors involved in building the ferries are JM Martinac Shipbuilding Corp, Nichols Brothers Boat Builders, Jesse Engineering Co and Vigor. The hulls are constructed by Vigor at its Harbour Island facility, while Nichols Brothers constructs and fits the main superstructure at its Freeland facility. Eltech Electric supplied the design and installation of the lighting, switchboards, power, control, interior communications and navigation equipment.

Nichols Brothers has been sub-contracted by Vigor Industrial to deliver a close-to-complete superstructure for the fourth ferry by spring 2016. Nichols Brothers is responsible for construction of the grand block section of the vessel including the upper car decks, exhaust stacks and pilothouses. Additional work includes all superstructure piping, windows, stairs, ladders, all exterior hand rails and painting the interior and exterior throughout.

A complex hydraulic transfer system will move the 1,100 tonne superstructure approximately 600ft from inside Nichols Brothers’ facility to a barge in Holmes Harbor. The barge will then transport the complete superstructure to Vigor’s Seattle facility to be joined with the hull and for complete final outfitting, and dock and sea trials.

The propulsion system for the Olympic class ferries consists of two main engines rated at 3000hp each, driving controllable pitch propellers through reduction gears at each end of the vessel. The two main engines are EMD 12-710G7C-T3, 12 cylinder, two cycle V type turbo charged, electronic fuel injection diesel engines. The two Falk 44x14DMH2S reduction gears are rated at 6,000hp. They contain internal hydraulic clutches capable of joining the two gear boxes together for combined operation. The amount and direction of thrust developed is controlled by varying the engine speed and the pitch on the propeller blades.

The Rolls-Royce propellers can be pitched in a positive (pushing) or negative (pulling) direction, with independent control of pitch at each end, to manage the amount and direction of thrust. The propeller at one end is driven in a counter clockwise direction, while the propeller at the other end is driven clockwise. Depending on the configuration of the six hydraulic clutches – three in each reduction gear box – the system can be set up for different modes of operation, with various configurations of engines and propellers. This means that independent control of engine speed and propeller pitch can be achieved on either end, or all 6,000hp developed by both engines can be used to drive the stern propeller, with the bow in a full feather position and its clutch disengaged.

The ZF Marine propulsion control system is a programmable logic controller-based electro-pneumatic remote control system that features two Rockwell Allen-Bradley SLC 500 programmable logic controller systems. Each uses a separate source of power, a separate set of digital and analogue input sensors, and a separate set of digital and analogue output drivers and devices.

On Tokitae and Samish, ship service electrical power is provided by three auxiliary Detroit Diesel Series 60 engines and Newage alternators rated at 300kW each. On Chinacum, three Volvo Penta D13 series engines and Newage alternators rated at 340kW each provide electrical power.

The ferries are equipped with highly manoeuvrable Rolls-Royce SV650-3 FCP rotary vane steering units, one at each end of the vessel. These systems utilise a spherical vane rotary actuator that is fitted to the top of the rudder stock and reacts like a hydraulic motor. It is activated by two hydraulic pumps that allow oil under pressure to enter three internal compartments around the circumference of the actuator. Three internal spherical shaped vanes attached to the rudder stock move in a direction corresponding to the pressure differential of the oil on either side of the three vanes.

The design of the Olympic class ferries was conceived with conventional diesel propulsion, but WSF has been developing plans to use liquefied natural gas (LNG) fuel systems for new ferries and retrofits. A further replacement programme to build at least three more Olympic class vessels is expected to take place in the early 2020s, although this will depend on WSF securing funding for additional ferries. If these orders go ahead, the vessels might feature LNG propulsion systems.

WSF has received US Coast Guard approval to retrofit the propulsion systems on the six existing Issaquah class ferries to use LNG fuel. Class society DNV GL has completed a risk assessment and safety plans. The retrofit involves fitting two LNG fuel tanks on the open top deck of each ferry.