HydrusOct 31, 2017 03:57 PM
San Francisco goes greener with new line of ferries
The 135-foot Hydrus is the lead boat in a new class of ferries for San Francisco. It is one of the earliest passenger vessels to enter service with a selective catalytic reduction (SCR) system.
Named for a small constellation, Hydrus became the brightest star in San Francisco’s Water Emergency Transportation Authority (WETA) fleet in April. The 135-foot aluminum catamaran also set the bar for greenest in the group, a noteworthy contribution in California’s quest for cleaner air and water.
The art of moving an ever-increasing number of commuters in this port city is an unrelenting challenge — perhaps struggle is a better word. The Golden Gate and Bay bridges are choked. Bay Area Rapid Transit (BART) is congested. The streets of San Francisco are clogged. The ferries are crowded.
To take some of the heat off, WETA, hit with a 74 percent increase in ridership since 2012, is undergoing an aggressive expansion of its fleet and terminals. Hydrus is the first in a series of four ferries scheduled to join the WETA fleet in the next two years, replacing M/V Encinal on the Alameda-San Francisco run. Designed by Incat Crowther and costing $15.1 million, Hydrus has seating for 400 passengers and racks for more than 50 bicycles.
The first two ferries, Hydrus and Cetus, which was delivered in July, were constructed in a joint venture between Nichols Brothers Boat Builders on Whidbey Island, Wash., and Kvichak Marine, now a Vigor company, at its Ballard shipyard on Seattle’s Ship Canal. The third and fourth ferries are being built solely at Vigor.
The construction process for Hydrus and Cetus repeated that of the four Gemini-class fast ferries delivered to WETA in 2009. Nichols Brothers built the superstructures and Kvichak began the hulls and decks prior to becoming a Vigor company. Once Vigor installed the propulsion systems, the catamaran hulls were towed to Whidbey Island to take on the superstructures, and then delivered to San Francisco.
Hydrus’ wheelhouse blends the latest in marine technology with the comfort of a luxury automobile.
Another three high-speed North Bay-class vessels, with a price tag of $19.2 million each, are scheduled to be built and delivered by Dakota Creek Industries of Anacortes, Wash., by the end of 2019. The vessels, capable of carrying 445 passengers and 50 bicycles, will operate on the North Bay-San Francisco run.
In 2009, the Gemini-class ferries, also designed by Incat Crowther, were the last word in aluminum catamaran ferry construction. They were designed and built to run fast, quiet, shallow and clean. Hydrus meets, and in many cases exceeds, those stringent design parameters.
Charles Walther of Walther Engineering Services, a consultant to WETA on both the Gemini- and Hydrus-class projects, said that owing to its longer length, Hydrus has an even lower wave profile than its Gemini predecessors. Improved maneuverability for the new vessel was accomplished by placing the rudders lower, changing to inboard-turning propellers and adding a bow thruster.
Because of the limited full-ahead speed required on runs in Central Bay, it was determined that 27 knots was an adequate speed for the Hydrus-class ferries. Originally the figure was 30 knots, but the drop in speed does not affect transit times significantly and can be achieved with two 12-cylinder diesels instead of two 16-cylinder units. Walther said the 12-cylinder engines meet the requirements for power and decreased emissions, and the smaller units also result in a lighter boat with reduced fuel and maintenance costs. Keeping the boat as light as possible was a strong design driver.
“A 27-knot operational speed required at least 1,800 horsepower,” Walther said. Hydrus achieved 27.9 knots loaded at 1,830 rpm during trials.
Pacific Power Group, after guaranteeing low-emissions compliance, supplied two MTU 12V 4000 Tier 3 main engines, a Hug Engineering selective catalytic reduction (SCR) aftertreatment system, and two John Deere/Marathon 99-kW Tier 3 gensets. Since most of WETA’s fleet and the city’s Golden Gate Ferry vessels are MTU-powered, crew familiarization and spare-parts commonality were considered in the engine choice.
Capt. Al Lewis mans the starboard control console to maneuver Hydrus at the dock. The 20-year San Francisco Bay ferry captain gives the new boat high marks for quality, comfort and functionality.
The builder contract called for emission levels lower than U.S. Environmental Protection Agency requirements. To achieve that, it was determined that an SCR system was the only choice. The system is fed by two 60-gallon urea tanks, each married to an engine in the pontoons. The system breaks down nitrogen oxides (NOx) by spraying the exhaust with urea as emissions leave the engine. In testing, Walther said the system netted an emissions reduction of more than 85 percent over Tier 2, about the same as Tier 4.
“The Hug SCR system is operational and is meeting the requirement for emissions, which was stated in the original RFP (request for proposal),” said Capt. Jason Covell, senior operations manager at Blue and Gold Fleet, WETA’s operations contractor. “Hydrus is performing quite well.”
Due to the large number of landings by the Hydrus-class vessels, passenger throughput was a critical consideration in order to achieve quick turnaround times.
“The passenger flow of the new (ferry) layout is a great improvement over the other vessels in service on the Oakland-Alameda service,” Covell said. “The aft bicycle storage allows for easy loading and offloading of bicycles and for the most part keeps bicycles out of the main passenger cabin. This run has seen an increase in bicycle traffic over the past few years.”
Patrick Robles, the senior deck hand aboard Hydrus, also acts in a customer relations and service capacity. He sees the boat through the eyes of a commuter and concurs with Covell that the new layout, free of obstructions that impede traffic flow, is much better.
Hydrus can accommodate up to 400 passengers, providing plenty of legroom and a comfortable ride in seating crafted of aluminum and woven bamboo fabric.
“This new boat (has) more than enough space for the high volume of bike commuters that we see every morning,” Robles said.
The Hydrus class has two passenger ramps, giving the crew the option to separate the passengers with bicycles, sending them to the aft ramp where the bike racks are located. And, of course, the crew has the option to load and unload at peak times using the ramps simultaneously.
“We have a great deal of flexibility and many new options for expediting the boarding process,” Robles said.
Hydrus could be called 50 shades of green. The boldest hue is the Hug SCR system and the propulsion chain consisting of the MTU engines connected to high-efficiency ZF reduction gears and five-blade CNC-machined Michigan Wheel nibral propellers. But there are many lighter shades of green that also reduce the vessel’s environmental footprint. A vinyl exterior covering is used instead of paint, and LED lighting has helped cut the electrical load. This enabled WETA to reduce the size of the gensets from 125 kW to 99 kW.
Solar panels feed batteries that power the electronics on Hydrus. “The solar panels charge the batteries in the day and the generator charges them when solar power is less than needed,” Walther said.
Although the runs are short, comfort was not sacrificed, and why not give a nod to the environment in the bargain? Australia-based UES Seating supplied the passenger seats, which are made of lightweight aluminum and woven bamboo fabric. All of the other furnishings are constructed of aluminum honeycomb panels that are not just extremely lightweight and attractive, but carry no fire load.
Tim Hanners, engineering and maintenance administrator for WETA, kneels alongside one of Hydrus’ MTU Tier 3 main engines.
Another comfort issue, noise, was also a top consideration. The superstructure is mounted on rubber blocks to minimize the noise and vibration transmitted through the hull by the machinery in the pontoons. In the machinery spaces, micro-perforated insulation cladding was installed throughout.
“Special consideration was given to the tunnel and propeller design, and the hull construction over the propeller areas,” Walther said. Sound insulation was applied to all of those sections.
The efforts paid off. Hydrus has exceptionally low noise levels and in many cases exceeds ABS Comfort Plus standards. “There is minimal noise. It is very quiet, inside and out,” Walther said.
All of the design and materials decisions were driven by the goal of achieving a high level of serviceability over the vessel’s life span, which is expected to run to 2042. To reduce corrosion, camber was built into the decks. To drive corrosion further into retreat, sealed cofferdams encircle the sewage pumps and selected bare aluminum areas are coated.
Serviceability was also the byword below decks, with the layout designed to provide easy access for maintenance. Special care was taken to address the difficulty of removing an engine if necessary; soft-patch covers on several decks facilitate lifting the units vertically.
Hydrus’ draft of 6 feet 9 inches (7 feet, 1 inch loaded) is attained by tunnels created in the pontoons to house the 50-by-54-inch custom Michigan Wheel propellers with P struts for less resistance. Adjustable interceptors are mounted on the transom of each pontoon to create lift without producing the drag of conventional trim tabs.
The ferry has an exhaust aftertreatment system, below, that uses urea to break down nitrogen oxides.
The low-wake hull form was designed to allow Hydrus to travel faster over the estuary without jeopardizing maneuverability, and the plumb bow maximizes the waterline length of the boat, resulting in lower resistance. Walther said that it all “works very well.”
In an alcove of touch-screen electronics and precision controls, Capt. Al Lewis referenced luxury automobiles and a well-known starship to describe being at the helm of Hydrus. Lewis, who has 20 years of experience as a captain on Bay ferries, including the Gemini class, praised the level of quality and functionality that Nichols, Vigor and Kvichak built into Hydrus.
“The wheelhouse is huge with tons of room and very comfortable seats,” he said. “And with two more boats coming soon, I anticipate they’ll handle the same, if not better.”
“Our captains are very impressed with the way the vessel handles and maneuvers near the dock,” Covell said. “The ride is very comfortable and the passenger cabin has very little engine noise. The design provides for a low wake at speed, which is important with all of the ship and tug traffic we experience on San Francisco Bay. The low wake benefits ship traffic and the impact on the shoreline is lessened.”
Hydrus is a very green boat in a blue and white coat.