Skip to main content

Going Green

Boating is on the brink of a revolution in fuel and propulsion technology

Boating is on the brink of a revolution in fuel and propulsion technology

The challengeshave been laid out clearly, and the race for marine fuel/power alternatives is under way in earnest.

Driven by an imposing array of forces — economic, environmental and political — researchers are striving to come up with cleaner and less costly methods of pushing a boat through water. Is biodiesel the answer? Electric, hybrid, solar, fuel cells? Some combination of those technologies?

Researchers are hard at work in each of these areas, but it’s the boater who ultimately will make the choice, says naval architect Dave Gerr, director of the Westlawn Institute of Marine Technology. “The winning technology will be the one that delivers what people want,” he says.

Most experts agree fossil fuels aren’t going anywhere for a while. But they acknowledge that consumer demand for cleaner, more efficient choices is increasing day by day. Public concern over greenhouse gas emissions and their impact on climate change is running high. And it’s a rare boater who now expects gasoline and diesel prices ever to return to a comfort zone.

New products such as the foldable electric Torqeedo Travel outboard, which won design and innovation awards at the Marine Equipment Trade Show in Amsterdam, Holland, and at the International Boatbuilders Exhibition & Conference in Miami last year, already are beginning to appear. Powered by lithium-manganese batteries that have a much higher energy density than common lead-acid batteries, the Torqeedo motors combine zero emissions and quiet operation with a variable-pitch propeller and electronic torque management. They are small and easy to stow, offer plenty of power, and run without emissions, which makes them a good alternative to trolling motors and older 2-stroke outboards.

Here’s an overview of developments in other areas.


By taking a 28-foot Zodiac 35,000 miles around the world, the Sunrider expedition proved in the early 1990s that biodiesel is a viable alternative fuel. Its advantages over regular petroleum diesel are many: It’s not distilled from crude oil; it produces fewer hydrocarbon and sulfur emissions and causes less air and water pollution; it’s less toxic and can be produced domestically; it’s a renewable energy source; it creates mechanical advantages through better lubricity; and it reduces exhaust odor and smoke.

Biodiesel is manufactured from vegetable oils (soy, canola, sunflower seed) or animal fats, and involves the base-catalyzed transesterification — a chemical exchange — of fatty acids with methanol. And, “it’s imported from the Midwest, not from the Mideast,” quips Deedee Chatham, director of business development at hudsonecoFuel, a Rhode Island biodiesel marketing firm.

Chatham’s company provided the B20 biodiesel blend (20 percent biodiesel, 80 percent conventional petrodiesel) to Oldport Marine Services in Newport, R.I., that fueled Oldport’s fleet of launches, shuttles, and tour- and workboats last summer.

“We noticed no difference to regular diesel,” says Oldport manager Matt Gineo. “The short-term benefits are cleaner-running engines and a nicer smell, which some customers compared to fries. In the long run, we’d expect engines to suffer less wear because of biodiesel’s better lubrication.”

Gineo emphasizes that no changes or modifications to the engines were required. His one-season experience with the fuel has made him a believer — “as long as it is readily available and the price is right.”

HudsonecoFuel says biodiesel, at $2.58 per gallon, beats the going price in Rhode Island for conventional marine diesel, which retailed for $2.65 to $2.99 early this year.

If it’s so cheap, so clean, so good for the engine, and it’s made in the USA, why is biodiesel still an obscure concept to most boaters? “Supply hasn’t caught up with the hype,” Chatham surmises. “Marina owners and fuel dock operators are critical for the distribution, and they will come around if consumers ask for it. The other issue is resistance to change and perhaps some fallout from the ethanol scare.”

Biodiesel doesn’t attack fiberglass tanks the way ethanol-enriched gasoline does, but there are a few simple things to keep in mind when switching over. “Change fuel and air filters early and often, then keep up with a regular schedule,” says Peter Bethune, who is preparing for a record non-stop circumnavigation in the wave-piercing power trimaran Earthrace, which runs on 100-percent biodiesel. Bethune crossed the Pacific from New Zealand to the United States without problems and is exhibiting Earthrace on a 36-city tour around the country.

“Fuel efficiency is down slightly, because 10 percent of biodiesel is oxygen, which causes a fuller combustion and increases apparent fuel consumption,” he says. Because pure biodiesel tends to solidify at low temperatures, he recommends the use of B20 blend or heated fuel lines when boating in colder climates. Older hoses, seals and gaskets should be replaced with synthetic products, because pure biodiesel can degrade natural rubber.

The biodiesel handbook published by CytoSource suggests U.S. engine manufacturers stand by their warranties as long as a fuel meets the American Society for Testing and Materials Specification D 975 standards. B20 blends of U.S.-made biodiesel do. However, CytoSource recommends contacting the engine manufacturer to be absolutely certain the warranty won’t be affected.

In touting biodiesel, Bethune invokes the here-and-now argument. “We have an obligation to look after the planet, and biodiesel helps us do that today,” he says.

Diesel-electric hybrid

Thanks to the success of so-called partial zero-emission vehicles, or PZEVs, like the Toyota Prius or some models of the Honda Civic, the public knows about hybrid propulsion. What most people do not know, however, is that in the 1990s the United States was a driving force in the development of hybrid cars but lost the advantage to Japanese automakers because domestic manufacturers and consumers embraced the Hummer culture.

The hybrid story might play out differently for recreational boats, however. Increasingly, they are being fitted with diesel-electric propulsion systems similar to those in locomotives or large cruising and Navy vessels. Hinckley Yachts kicked off the buzz with hull No. 1 of its 42 DS in 2004, a daysailer powered by a Solomon Technologies diesel-electric system. Solomon, which also licenses technology to the Hobie Cat Co., is currently embroiled in a lawsuit with Toyota, alleging a patent infringement in the Hybrid Synergy Drive system of popular hybrid vehicles, including the Prius.

Others, meanwhile, are aggressively marketing diesel-electric vessel propulsion that combines two existing technologies: electric DC motors to drive the engine shaft and diesel generators and battery banks to supply the power.

“I wouldn’t consider diesel-electric drive systems for planing hulls, but for displacement hulls of trawlers and cruising sailboats they are good,” says Jim Antrim, an El Sobrante, Calif., naval architect who also has designed electric boats.

Early systems reportedly suffered from capacity problems due to undersized generators and battery banks, but the learning curve has flattened. “It’s all about efficiency and minimizing electric losses,” says Kevin Alston, CEO of Glacier Bay, an Oakland company that provides diesel-electric systems to several yacht builders. “Generator and electric motor have to be designed for this purpose. The key advantage of an efficient diesel-electric system is decoupling the power for the prop from the diesel engine’s speed, which lets the genset run at peak power while the prop may only need 50 percent.”

Thanks to sophisticated electronic controllers, and “self-optimization,” diesel-electric systems can handle varying load requirements very efficiently, such as when a trawler powers up and down long swells. But there are other benefits as well.

“It creates space, plain and simple,” explains Joseph Garasic, chief of Legacy Yachts, a Florida builder that is introducing a 32-foot trawler with an Ossa Powerlite system from Glacier Bay. “Because electric motors are smaller than comparable diesels and a generator can live in a closet, we can either fit a second motor or an extra stateroom.”

Garasic says exchanging components is much easier with diesel-electric propulsion; he calls it “a safety factor for offshore operation.” His colleague Reuben Trane, president of Island Pilot, recently announced a new 40-foot deck-saloon power cruising cat with diesel-electric propulsion (see accompanying story).

“Combined with solar panels and an efficient hull shape, our new DSe Hybrid might go from Florida’s eastern shore to Bimini and back on less than 25 gallons of diesel,” he says.

French catamaran builder Lagoon already is ahead of the curve. Last August, the company introduced its new Lagoon 420, a 42-foot cruising cat with diesel-electric propulsion. “At this time, it is the only model we sell with this kind of system,” says Nick Harvey at Lagoon’s U.S. office. “But it might become an option on other models, too.” Harvey says the two 10 kW motors provide a top speed of about 8 knots. If the charge of the 72-volt battery bank falls to 80 percent, the 13.5 kW, 110V/60 Hz genset comes on automatically. Manual override allows running down the batteries to 60 percent, which takes about 120 minutes, depending on the load.

Lagoon uses a mix of international suppliers for its propulsion system and claims to have sold all the 420s for 2007 — around 70 boats — with 25 percent going to the United States. At press time, Catalina Yachts and Fischer-Panda USA were evaluating the viability of the Whisperprop diesel-electric system for the Catalina Morgan 440.


French physicist Alexandre-Edmond Becquerel discovered the photovoltaic effect in 1839, and in 1883 Charles Fritts is said to have built the first solar cell by coating selenium with a thin layer of gold. Starting in the 1950s, space exploration pushed the development of solar cells to power satellites and other spacecraft, such as the International Space Station.

Solar energy shines because it’s clean, quiet and is distributed to the user at no cost. But the dark side of photovoltaic panels is their low efficiency and high cost compared to other forms of energy extraction. A large number (and area) of solar panels is necessary to generate enough electricity for propulsion purposes.

“Most thin-film silicon panels, which are popular on RVs and boats, have a rated efficiency of approximately 10 percent,” says Steve Heckroth, a California alternative energy consultant who has lived off the grid for more than 20 years. “In my experience, a kilowatt hour of electricity produced from sun at 20 cents can be up to 10 times as costly as the same amount produced by a wind turbine.”

On the other hand, solar power also has the energy to generate publicity. The sun21, a Swiss 46-foot catamaran, was nominated by Time magazine for Invention of the Year 2006 for its attempt to cross the Atlantic powered by nothing but sunlight, which is harnessed by two 5 kW solar modules arranged on a flat 700-square-foot “sunroof.” (See accompanying story.) Projected average speed for the 7,000-mile trip, which includes stopovers in the Caribbean and East Coast ports, is 5 knots. The Swiss organizers view the voyage as an effort to “use renewable energy … and to release political energy.”

Much of that political energy already is flowing in San Francisco, where city-owned diesel vehicles and equipment must use B20 biodiesel by the end of 2007. In this climate, a concession for the lucrative (a million passengers a year) 20-minute ferry run from Fisherman’s Wharf to Alcatraz can only be won with low-emission vessels. To beat out the previous concessionaire — Blue & Gold Fleet — Hornblower Cruises & Events consulted with Solar Sailor of Australia and proposed the Hornblower Hybrid, a vessel that uses a combination of technologies, including diesel-electric, solar and wind.

“We scored high because we will minimize emissions by blending existing technologies,” says Hornblower president Terry McRae. He compares the new ferries to a “Prius on the water.” Design details are still up in the air, but McRae suggests a multihull that can carry at least 300 passengers and uses diesel-electric propulsion and a solar wing that can double as a sail. The proposed launch date for the new service is the end of 2008.

Hydrogen fuel cells array

The mélange of technology for the zero-emission market wouldn’t be complete without hydrogen fuel cells. Even before the Bush administration began touting this technology as deliverance from oil addiction, the German company MTU Friedrichshafen introduced No. 1, an experimental propulsion system for recreational vessels based on gel batteries and fuel cells.

MTU’s CoolCell system draws hydrogen from a tank and oxygen from the air to generate electricity with the help of a polymer proton exchange membrane. The emission is only water, so it’s clean, but there still are formidable drawbacks, such as limited range and exorbitant cost.

Marshall Duffield, president of the Duffy Electric Boat Co., an Adelanto, Calif., builder of battery-powered boats, advocates hydrogen cells and believes they eventually will take zero-emission boats much farther than batteries ever could. “We have a4 kW experimental fuel-cell system for our Duffy 30 model that can carry 23 people and does 7.5 knots,” he says. To further prove that the technology is viable, Duffy says he also offers a fuel-cell battery charger.

“Our next step is producing hydrogen on demand from sea water so we don’t have to lug it around in a humongous tank,” he says.

Fuel-cell technology does work, Duffy asserts, but he concedes that the cost now is off the charts. “Like with space exploration, the government needs to step in and help fund the development of fuel-cell technology,” he says.

Hull shapes

Another part of the efficiency puzzle is a vessel’s hull shape — a big factor in efficiency and fuel consumption.

“There are two basic questions to ask: How fast do I want to go, and how do I use my boat?” says Westlawn’s Gerr. “Displacement vessels benefit from narrow beam and long waterline. Slippery, meaning a speed-to-length ratio of [about] 1.5, is efficient and lowers fuel consumption. Contrary to myth, long and narrow hulls also make good seagoing boats, but they limit interior volume, and that isn’t popular with mainstream consumers.”

What about weight? “Light is fast, that’s true, but you have to be careful because a light boat can be uncomfortable in a seaway,” says Gerr.

Naval architect Antrim’s record-breaking Duffy Voyager design illustrates this theory. “It’s 62 feet in length overall, has less than 34 inches of maximum beam in the center hull, and displaces 4,200 pounds — 3,400 of which are made up by batteries and the 13-hp DC motor,” Antrim says. “It did its job and broke records, but there was only space for the driver.”

Looking at semidisplacement boats, Gerr thinks the future belongs to power cats because they combine space and efficiency. He sees only limited improvements for planing hull shapes because they have been pushed for speed for a long time.

Asked about propulsion technology, Gerr likes diesel-electric for long-range cruisers, “because they have a flat torque curve and can be optimized for changing load requirements,” but he refuses to name one “killer” application.

Gerr remains convinced that boaters will vote with their wallets, but it seems a foregone conclusion that fewer trips to the fuel pump and environmental concerns will figure prominently in their decisions.