• Major Project

Ferry system electrification

Tokitae out on the harbor

Major Project overview

Washington State Ferries (WSF) is embarking on an ambitious initiative to begin the transition to an emission-free fleet through a hybrid electric ferry system. WSF operates the largest ferry system in the United States. It is also the biggest contributor of greenhouse gas emissions of any state agency in Washington, burning 19 million gallons of diesel fuel to support 24 million passengers every year.

This shift to hybrid electric ferries is in response to governor and legislative direction as well as alignment with the agency’s own long-range planning initiatives. To transition to a hybrid electric fleet, WSF is working on the three key elements of the electrification system – building new vessels, converting vessels, and electrifying the terminals.

Timeline overview


Major project status



$1.33 billion secured funding | $3.98 billion total estimated cost

Major project alerts

Through a competitive process completed in Nov. 2022, WSF selected Hill International, Inc. and its team to serve as the General Engineering Consultant (GEC) for the electrification program.
Suanne Pelley
Major Construction Communications Manager

Summer 2023 electrification update

Jumbo Mark II Conversions

Following a competitive process among Washington shipbuilders, in August 2023, Washington State Ferries awarded Vigor Marine a $150 million contract to convert the agency’s three largest ferries to hybrid electric power. This contract is for conversion of two vessels at approximately $100 million with a fixed-price option to convert the third vessel in 2025.   

The Jumbo Mark II vessels are the largest in WSF’s fleet and produce 26% of WSF’s total annual greenhouse gas emissions. They also serve the most densely populated urban areas in Central Sound. This September, Vigor Marine will start work on Wenatchee, expected to reenter service next summer. Vigor will also begin converting Tacoma in 2024, with the option to convert Puyallup in 2025.

While converting the vessels to hybrid electric power, Vigor Marine will modernize the ship’s controls and other outdated systems. These updates will improve reliability and help ensure these 22-year-old ferries serve our communities for decades longer.   

Jumbo Mark II Hybrid-Electric Conversion FAQ

Q: How will you convert the Jumbo Mark II ferries to hybrid-electric power?

A: Our existing Jumbo Mark II vessels use diesel electric propulsion. They have four diesel engines that power generators, and those generators power two propulsion motors on each end of the vessel. The motors activate the propellers to move the vessel through the water. When we convert these vessels to hybrid-electric power, we’ll remove two of the four engines and replace them with two battery banks. These battery banks will store and send energy to motors like diesel generators.

Q: How will this work improve vessel reliability?

A: While we’re converting the Jumbo Mark II’s to hybrid-electric power, we’ll also update elements of the 20-year-old propulsion system, ensuring these vessels can reach their 60-year lifespan. These updates will allow the vessels to operate more efficiently and reduce the amount maintenance and repairs that would take them out of service.  Combining the conversion to hybrid-electric power with planned updates to the propulsion systems will also reduce service interruptions.

Q: Will hybrid-electric conversion impact the capacity, speed, or dock time of the vessels?

A: The Jumbo Mark II conversions will not reduce vehicle or passenger capacities (202 vehicles and 2,500 passengers) or vessel speeds. The addition of the battery banks and other systems will increase the vessel weight by about 140 long tons (2,240 lbs. per long ton), which is about three percent. Once the terminals have charging capacity, we’ll carry less fuel, compensating for the increased weight. Vessels will charge each time they dock at a charging terminal. We based the design on our current operational schedule, with charging times that fit within our typical 20-minute time at dock used for unloading and loading passengers and vehicles.  

Q: Why convert to hybrid-electric and not full electric?

A: Hybrid-electric power is our best option for system resiliency. Keeping diesel as a backup power source ensures we can continue service while building terminal charging infrastructure and the case of any issues with the batteries or interruptions to our shore-based electric power. 

Q: Are the batteries safe? Is there a concern for fires caused by the batteries?

A: We’re implementing a rigorously tested safety and fire suppression system on our Jumbo Mark IIs. Battery cells are isolated from each other and closed off from the rest of the ship, each regularly monitored for voltage, temperature, and humidity and installed with a cooling system. All battery-related equipment goes through destructive testing and a review by the US Coast Guard.

Q: How long will the batteries last and how much do they cost?

A: Each battery lasts approximately four years before they need replacement. Replacement batteries cost approximately $1.37 million. Each hybrid-electric vessel will save approximately $6.5 million in fuel costs in the same four-year period.  Once terminals provide charging power, each vessel will save almost $32 million in fuel costs per four years.

Q: Will there be enough electricity to charge the ferries?

A: We’re developing agreements with local utilities to ensure that residential and business customers have the energy they need, especially on high demand days. In the instance that the vessel doesn’t have the time or energy to fully charge, we can rely on our diesel power.

Hybrid electric Olympic Class vessels 

In fall 2023, WSF plans to post a new draft Invitation for Bid (IFB) for up to five new hybrid electric Olympic Class (HEOC) ferries. Interested parties can review and propose changes to the IFB before WSF issues the final IFB in early 2024. To receive interested parties email updates, contact WSFelectrification@wsdot.wa.gov.

New procurement opportunities for HEOC vessels

On May 11, 2023, Governor Inslee signed into law HB 1846.  This bill allows WSF to explore new procurement options, including:  

  • contracting through either design-build or design-bid-build;  
  • opening the bid process to shipbuilders outside of Washington state, including a provision by which the department must award a credit of 13 percent of the bid price for bid proposals for vessels constructed in the state of Washington, which must be adjusted to reflect the proportion of the construction of the vessels that occurs within the state; and 
  • using a one- or two-contract approach to accelerate vessel delivery, with a minimum of two vessels and up to five vessels in a contract.  

WSF is working to implement the full legislation in our procurement process. We encourage any contractors interested in working on this project to review this legislation in advance of our contract solicitation.   

Terminal electrification

WSF is in the process of planning and designing charging infrastructure at our ferry terminals. This effort begins with ensuring that each terminal will be able to source sufficient energy through collaboration with local utilities.

In May 2023, WSF began a partnership with Puget Sound Energy to add high-speed ferry charging capabilities to eight additional terminals, starting with Bainbridge Island. WSF and Seattle City Light signed a similar Memorandum of Understanding in September 2022 to provide power to Colman Dock.

Additional resources

For a primer on WSF’s electrification efforts, please see this video:

For a more in-depth look at our ferry electrification efforts, watch the extended video.