TBT – The Revolutionary Duffy Power Rudder

In his excellent book and comprehensive book, Electric Boats and Ships: A History (buy on Amazon) author Kevin Desmond gives a few accounts of the early and ongoing history of Duffy Electric Boats, certainly one of the world’s best known and most successful electric boat manufacturers.

Desmond writes about the beginnings of the company in Electric Boats and Ships:

Marshall Duffield, Sr., quarterbacked USC’s 1930 Rose Bowl–winning team, earning the nickname “Field Marshall”, then launched a successful career in wholesale liquor, developed real estate in California, built the Rancho San Joaquin golf course, and along the way he and his wife raised a son, born in 1952 and named Marshall Dixon Duffield, Jr.

Duffy Jr.  (that’s him in the photograph above, taken in 1970) grew up in a waterfront home beside Newport Bay, California, sailing, tinkering with motors, inventing. He sketched sailboats in his bedroom and built a tank in his yard to test his models.

In the summer of 1969, before his senior year in high school, Duffy grew frustrated with the constant breakdowns of his family’s gas-powered runabout. He was advised by his friend Kurt Olsen that one way to solve the problem would be to put a golf cart motor in it. Duffy asked his father for a $300 loan to buy an old cart with an electric motor. Outside a Quonset hut his father owned on 17th Street in Costa Mesa, Duffy and his friend Jack A. Heiser tested the first electric boat engine.

Six patents awarded in five years

a group of young people in an electric boat in the 1970s
The 1st Duffy in Newport harbour, 1970

Almost a half century after its founding in 1970 some 14,000 Duffy Boats now ply inland and ocean waters all over the world, and the book has a few other entertaining anecdotes about the origins of the boat company and the ambitious, colourful and ingenious Duffy Jr., who received 6 US patents over 5 years in the early 1990s.

Our Throwback Thursday is about one of those items, the Duffy Power Rudder: U.S. Patent 6503109 B1. We’ll let Mr. Desmond carry on:

Duffy wanted to perfect his idea of a rotating power drive, knowing this was the best way to push a small boat, allowing much more room to the interior, easier installation, superior maneuverability, quieter operating, and less servicing.

Duffy, along with Alex Kozloff and Charlie Sparkle, built and refined the drive unit for three years. The rudder had in it a spiral bevel gear that drove a prop shaft out the rear of the rudder, and the drive shaft went up inside the boat where the motor was coupled to it. All of this turned and gave the drive great maneuverability.  (NOTE: It also prompted Duffy to switch to a pancake design motor which was smaller, lighter and put out more horsepower.)

The Power Rudder revolution was an expensive, time-consuming adventure for Duffy because to use the Power Rudder each boat in the Duffy line had to be redesigned from the hull up. It took four years to finally finish new molds for every size boat Duffy offers, the task being completed in 2008.

Innovations keep coming

On the Duffy Electric Boat website there is a page dedicated to the operation of the Power Rudder, which allows a Duffy Boat to turn within its own length. It is a pretty remarkable bit of engineering, which you can see in this video from the company.

And ‘Duffy’ today? Well, Newport Beach, where he launched his first boat, is now home to the world’s largest collection of Duffy Boat owners – with 3,500+ boats in the water. Fittingly, Marshall Dixon Duffield Jr. got into politics and joined the town council in 2014, served as pro tem Mayor for one year and was reelected to council in December 2018.

The long history of electric boats is filled with unique characters like Duffy, or Alan Freeman, who invented the world’s first solar boat as a solution to the 1973 oil crisis. Today we have people like Alain Thibault developing the SeaBubbles flying water taxi and ferry-sized FlyBus. Or Nick Leason of LiftFoils, Dan Montague of Jetfoiler and the others at the forefront of the electric hydrofoil jetboard experience. In many ways the history of electric boats is just getting started. Welcome aboard!


»» Check out our other Throwback Thursdays
»» Read about some recent electric boat World 1sts

Electric Boats and Ships: A History
Available from Amazon, including Kindle

Amazon Customer Review: “Desmond’s new book leaves no doubt that electrically powered vehicles are already a fixture on the firmament of propulsion and will continue to be so for the foreseeable future. Well illustrated, meticulously written and researched, this book is a guaranteed ‘must’ on the bookshelves of all who have interest in this subject.


DISCLOSURE: The excerpts and photographs from Electric Boats and Ships: A History have been provided by Mr. Desmond and the book’s publishers at the request of Plugboats. Plugboats receives a standard Amazon affiliate commission for any copies purchased through the links on this site.

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