The Enhydra, a lithium-ion battery powered electric passenger excursion vessel has launched by the Red and White Fleet, San Francisco, and builder All American Marine, Inc., Bellingham, Wash.

The 128’x30’ aluminum monohull was designed by Nic de Wall of Teknicraft Design, Auckland, New Zealand, and at 600 passenger capacity is the largest hybrid powered passenger vessel to be built in the U.S. under Coast Guard Subchapter K rules. It follows by a few months the Seastreak Commodore, a Tier 3 diesel powered New York commuter ferry that was the first U.S.-built Subchapter K vessel for 600 passengers.

In contrast, the Enhydra is specifically designed for silent running harbor tours of San Francisco Bay and the Golden Gate Bridge. Guests will experience views of the bay and cityscape from all three decks, with snack bars on each level, while the electric drive quietly motors them past the sights. The first passengers will ride this fall.

"It's currently going through sea trials and we hope to turn over the keys at the end of the month," said All American Marine CEO Matt Mullett.

The second deck has full, wrap-around panoramic viewing deck, with access to an enlarged-bow foredeck. The third level is entirely open with outdoor seating.

Initially the Red and White team investigated steel monohull designs for the new vessel, AAM officials say they demonstrated there would be considerable savings in building and maintenance costs with an aluminum design, while ensuring a robust hull structure.

Founded in 1892, the Red and White is one of the oldest businesses on the bay and practices environmental sustainability and community education that is valued in the city. San Francisco’s public ferry system is recapitalizing its fleet with an emphasis on low-emission vessels, and the Red and White operators have been working for some time on feasible hybrid power.

They found it in propulsion system integrator BAE Systems, which supplied their HybriDrive propulsion system. It includes a generator, propulsion power converter, house load power supply and control system.

The generator is mounted to a variable speed Cummins QSL9 410-hp diesel engine. The system offers parallel hybrid powering of the AC traction motor from either the generator, the batteries, or both. The motor is coupled to the propulsion shaft via a reduction gear for thrust and increased propeller efficiency.

With this configuration, torque is immediately available for the propeller, and the speed can be precisely controlled, according to AAM officials.

“The Enhydra will not only be more sustainable in fuel consumption, but it will also lessen impact on local marine life,” AAM and Red and White said in a joint statement. “When powering the vessel, the electric motors are noticeably quieter, resulting in less noise and vibration, and a significantly reduced environmental footprint overall.”

“We are proud to introduce such a large-capacity hybrid technology vessel and working with such great partners such as Red and White Fleet and BAE Systems to develop and build the boat of the future," All American Marine CEO Matt Mullett said. "All American is working to stay at the forefront of the decarbonization movement in the maritime industry, and the lithium-ion hybrid electric propulsion system on the Enhydra is a step in the right direction.”

Part of the payoff is BAE Systems’ HybriGen system has lower engine operating hours and is more streamlined than a conventional drive, requiring fewer parts, and saves both fuel and maintenance costs.

“Adding Enhydra to Red and White Fleet exhibits the company’s environmental commitment while providing an acceptable return on investment,” the companies said.

The hybrid system also uses battery power from two 80-kWh lithium-ion battery packs from Corvus Energy, Richmond, British Columbia, Canada, supplied under their next- generation Orca Energy line.

A key feature of the Enhydra’s design is capability to expand the size of the batteries, with a goal of achieving complete zero- emissions operations in the future as charging infrastructure advances and battery technology improves.

As built, the current battery system can meet any power demands of the Enhydra, while providing silent, emissions-free experiences for passengers during their sightseeing cruises.

The HybridDrive system automatically uses full electric battery operation at slower speeds and when maneuvering in and out of the harbor, driving two Veem Star 4-blade propellers. At higher speeds, the generator will automatically engage and augment the additional power demands of the traction motor.

The innovative design and quality construction of the Enhydra make Red and White Fleet’s vice president of operations Joe Burgard hopeful for future possibilities.

“We are very pleased with the team All American Marine has put together to deliver this unique vessel and are eager for our guests to experience San Francisco Bay from the silent decks of the Enhydra,” Burgard said. "We see the propulsion configuration on the Enhydra as phase one in our move toward the full electrification of our fleet. Stay tuned for phase two."


Contributing Editor Kirk Moore was a reporter for the Asbury Park Press for over 30 years before joining WorkBoat in 2015. He wrote several award-winning stories on marine, environmental, coastal and military issues that helped drive federal and state government policy changes. He has also been an editor for WorkBoat’s sister publication, National Fisherman, for over 25 years. Moore was awarded the Online News Association 2011 Knight Award for Public Service for the “Barnegat Bay Under Stress,” 2010 series that led to the New Jersey state government’s restoration plan. He lives in West Creek, N.J.