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to recoup the difference in cost over a standard propulsion system.

I'd welcome any further thoughts you might have on this, and would be happy to chat with you on the phone anytime.

Cheers, Dave

Dave:

It wasn’t immediately clear to me, did you write the sidebar on the misperception of hybrid’s efficiency? If so, bravo, I applaud you. It was spot on.

Sincerely, Steve D'Antonio

Steve D'Antonio Marine Consulting, Inc.

www.stevedmarineconsulting.com

Dave Gerr replies:

Steve:

Yep, that was a sidebar to the efficiency article and I did write it all. Glad you enjoyed it.

Cheers, Dave

Dave:

Several years ago I piloted a 30 foot trawler from Virginia to Bermuda. Made it in about 4 days using a Yanmar 50 hp and we sipped fuel. While we refilled there, we probably could have come back with what was board. To your point, efficient vessels can easily make long passages while using little fuel, and the vessel I made the passage aboard was anything but long and slender!

Whenever the subject of hybrids comes up at the magazines for which I write or in the lectures I deliver, I offer precisely this view, it may be quieter and if you use solar panels you may get a free lunch of sorts, but under most cruising condi-tions diesel/electric hybrid systems are less efficient than a modern, conventional, properly-loaded diesel engine and drive train. The cruise ship analogy invariably comes up, along with many tugboats. There was recently an article about a couple of tugboat conversions in California where the operators were claiming significant fuel savings after the switch.

Sincerely, Steve D'Antonio

Steve D'Antonio Marine Consulting, Inc.

www.stevedmarineconsulting.com

Dave Gerr replies:

Steve:

Yes, we agree on the lack of efficiency gains from most h brid-propulsion packages on boats. In spite of this, I susp we'll see still more hybrids on boats. There's a well-intentioned and understandable desire to be “green.” Sin hybrid technology is accepted as green and cutting-edge land vehicles, it's all too easy for well-intentioned investo and buyers to be drawn to hybrid for boats.

In fact, the real efficiency gains are from improvement in hull form (longer and more slender and lighter); going a b slower as a proportion of hull speed; and improving the c ventional propulsion-package's efficiency. Doing all three yields significant efficiency gains—sometimes very signifi cant. This is real "green" propulsion.

Sadly--in the public mind--this sensible, straightforward a proach doesn't appear to have the sex appeal of hybrid p pulsion. Accordingly—even thought the conventional ap-proach is superior—the real efficiency gains from it don't generate the interest and excitement that the new-fangle hybrid technology offers. This even though the so-called gains from most hybrid installations on boats are illusory

Of course, there are specialized vessels that do gain from hybrid propulsion. I mentioned cruise ships in the article. Tugs are another good example of special-use vessels th can and do see real improvements from going diesel/ electric (hybrid). This is because the main engines on tug are immensely more powerful than needed to drive the t alone. When tugs are running free (without a tow), their c ventional engines are dramatically underloaded--inefficie By changing to diesel/electric propulsion, tugs can opera on just one or two of their electric generators while free r ning, only switching on all their generating capacity durin power-intensive towing operations.

Cheers, Dave

Dave:

Agreed on all points. Then there’s the immense complexi of most recreational marine hybrids, but that’s another story.

Sincerely, Steve D'Antonio

Steve D'Antonio Marine Consulting, Inc.

www.stevedmarineconsulting.com

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