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Ferries – MV Hyak Hybrid Project

Super Class ferry Hyak

M/V Hyak in Elliott Bay.View more photos of the Hyak.


Summer 2015

  • This project will convert the M/V Hyak from diesel powered generators to hybrid diesel-electric powered generators.
  • The conversion will save more than 234,600 gallons of diesel fuel annually.



The Hyak was built in 1967. At that time, the most reliable and efficient way to power a vessel of its size was with four large diesel generators and a pair of diesel-powered propulsion motors. Today, nearly 50 years later, technology has evolved to the point where it is possible to power the Hyak with a combination of diesel and electric fuel.

We will remove all four original diesel generators and diesel-powered propulsion motors and replace them with four new generators and two new motors fueled by hybrid diesel-electric technology.

The hybrid Hyak will be much more energy efficient, saving 234,677 gallons of diesel fuel annually.

Why is WSDOT converting the Hyak to hybrid power?
Currently, the generators powering the Hyak are able to run at full power or no power at all. This means the generators run full power, even when full power is not needed. In 1967, when the Hyak was built, powering Super class ferries with all-or-nothing generators was the best technology available. It allowed the vessel to operate consistently without power failures. However, this is like keeping a car engine open full throttle while waiting at a stop light.

Technology has improved significantly in the past 47 years. The hybrid Hyak will be converted to modern diesel-electric generators that can operate at changeable or variable speeds. This means they will be capable of supplying more power when needed, such as during a crossing, or slowing down when demand is low, such as loading and unloading at the dock. Generators that are able to match the required speed of the vessel are more fuel efficient because they consistently use the right amount of power needed to match the required speed, no more and no less.

Additionally, we will replace both out-dated diesel propulsion motors with hybrid motors that can run on a combination of batteries and diesel fuel.  

Will the other Super class vessels be converted to hybrid power?

There are four vessels in our Super class fleet: Hyak, Kaleetan, Elwha and Yakima. All of the vessels were built in 1967, and all except for the Hyak received generator and motor upgrades during the 1990's and early 2000's. The Hyak was not upgraded at that time because it was mostly used as a standby vessel, and therefore not a priority for an upgrade.

Now that the Hyak has been pressed into regular daily service, it is due for a generator and motor upgrade. Converting the vessel to hybrid fuel technology will reduce emissions and save more than 4 million gallons of diesel fuel during the Hyak's remaining service life, approximately 17 more years (2031).

The End Result
The Hyak will have a reliable and efficient propulsion system with cutting-edge hybrid technology, saving fuel and reducing emissions.

Project Benefits
The Hyak currently burns an average of 1.34 million gallons of fuel per year, and we hope to save 20 percent of that after the conversion. Fuel savings could total about $21.5 million over the remaining life of the vessel.

The conversion will also reduce emissions. Reduction in carbon dioxide will be 2,674 metric tons per year; particulates will be reduced by nearly 1 metric ton per year, and nitrous oxide will be reduced by 17 metric tons per year.

It will also save on engine wear and tear. Maintenance savings will be about $1.2 million over the remaining life of the vessel.

What is the project timeline?

  • March - April 2014: Request for proposals by potential contractors
  • June 2014: Award contract -Update: On hold as of summer 2014.
  • October 2015-May 2016: Conversion work
  • June 2016: Sea trials
  • Fall 2016: Hyak back in service as hybrid

Financial Information

The Hyak conversion will cost approximately $22 million.

Other hybrid ferries around the world
Construction and use of hybrid ferries has increased world-wide in recent years. Below are some examples.

How can I get more information?
Broch Bender
WSF Communications Consultant

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