Propane outboards: Will they catch on?


What started as an idea on a research vessel in the North Sea several years ago soon could be coming to a dinghy or a tender near you: the propane-powered outboard. It’s an attempt by Lehr Inc., of Los Angeles, to boost affordable sustainable-propulsion technology for a mass market, based on the belief that the world eventually will shift to gaseous fuels.

California-based Lehr has introduced 2.5- and 5-hp outboards powered by propane.

Propane already is used in buses, cabs, forklifts, gardening equipment, go-karts and small scooters, so why not try it in small outboards? “There are many upsides to propane-powered propulsion,” says Bernardo Herzer, a licensed captain and the CEO of Lehr, which has introduced 2.5- and 5-hp outboards ( The gas is clean, relatively cheap and readily available, and it’s not imported from politically volatile regions.

As a captain of a research ship, Herzer says he grew irritated by the noise and fumes from combustion engines on board, so he explored the possibility of using clean-burning and odor-free propane as a fuel source. After all, he thought, if it works on the galley stove, it might work for propulsion, too. “It helps the U.S. and the environment,” he says.

Although propane is cleaner than gasoline or diesel, it isn’t zero-emission or a renewable source of energy. For example, as a byproduct of oil extraction in Prudhoe Bay, Alaska, propane needs to be separated from crude in large gas plants before it gets pumped back into the ground, where it pressurizes oil reservoirs or acts as a solvent that separates oil from rock. Some of it is also used as a refrigerant and the rest is sold for heating and propulsion purposes. At a time when the price of heating oil is increasing sharply, propane is attracting considerable political and economic interest.

Lehr says propane produces 25 percent less carbon dioxide and as much as 60 percent less carbon monoxide while reducing the emission of ultra-fine particulates by 97 percent. Propane also has 96 percent fewer carcinogenic emissions than gasoline and has no ozone-depleting potential, according to Lehr.

Lehr says a gallon of propane can power a 5-hp outboard for as long as two hours and the 2.5-hp model for as long as four hours.

Herzer also asserts that Lehr’s engines are more efficient than comparable gasoline-burning outboards. “This is not a conversion of an engine that was designed to burn gasoline,” he says. “It was designed and optimized to burn propane, which is rated at 110 octane, and the more octane, the higher the efficiency.”

Comparing the fuel consumption of gasoline- and propane-powered outboards of equal size, Lehr estimates the potential annual savings in fuel costs to lie between $26 for a 2.5-hp engine and $1,841 for a 175-hp model. This calculation assumes an annual average engine run time of 57 hours, a gasoline price of $3.72 a gallon and a propane cost of $2.42 a gallon.

Propane liquefies at a pressure of 80 to 120 pounds per square inch, which is much less than the 3,000 to 3,600 psi required to compress natural gas for use as an engine fuel, so propane tanks don’t have to be as massive, which significantly reduces weight. According to Lehr, a gallon can power a 5-hp outboard for as long as two hours and the 2.5-hp model for as long as four hours.

Another advantage of the propane outboard is that it sidesteps the troublesome ethanol issue. Ethanol fuel does not sit well with gasoline marine engines. To paraphrase Herzer: no ethanol, no water, no additives, no problem.

Lehr holds 37 patents and has won the EPA Clean Air Excellence Award and the Popular Mechanics Breakthrough Product Award. The company also won the National Marine Manufacturers Association’s 2012 Innovation Award in the environmental category. Since the company filed for incorporation in 2007, it has gone through several rounds of funding, including Series A Preferred Investment in 2009-10, and licensed its technology to Fiskars, a manufacturer of lawn care equipment.

It also signed a co-branding deal with Craftsman and secured vendor agreements with Walmart, Ace Hardware, The Home Depot, True Value and Sears, among others. The outboards will be sold through Donovan Marine, Discount Marine Mart and other marine retailers, including participating West Marine stores. Suggested retail prices range from $1,200 for the 2.5-hp short shaft to $1,956 for the 5-hp long shaft. Lehr says it sources parts from around the world, but builds the engines in China. Models rated at 10 hp and 25 hp are said to be on the drawing board.

Bernardo Herzer, CEO of Lehr, formerly captained a research ship.

Herzer hopes propane outboards will take off because they will strike a chord with people who already use the gas in other applications. They might be fueling their backyard barbecue, their camping lanterns, their lawnmowers, leaf blowers and string trimmers with it. These devices use disposable 16.4-ounce propane canisters that are sold through outdoor equipment retailers. This so-called “twist-and-go option” is also available on the outboards, which alternatively can be connected to a remote fuel tank, such as a refillable propane bottle or Lehr’s own see-through composite tanks, via fuel line hose.

“Imagine you go out on a fishing trip with this propane outboard,” he says. “You can connect a chain of other devices, including a fishing lantern and a barbecue. You can’t do that with any other fuel.”

This article originally appeared in the June 2102 issue.