In 2012 the Lehr corporation released two models of a propane-powered outboard engine: 5 and 2.5-horsepower motors. Available in both standard short- and long-shaft versions, these 4-stroke outboards can be used on any boat requiring these power levels. (Larger models are reportedly in development.) They offer a number of advantages over standard gasoline-powered outboards while being priced about the same.
While these outboards are new products, Lehr has been building award-winning propane-powered engines for some time and has gained a reputation for quality products that are also good for the environment. Their other products powered by propane include lawn mowers, weed-whackers, and blower/vacuums. The founder of Lehr, Bernardo Jorge Herzer, is a licensed ship's captain with decades of sea experience who has seen firsthand the environmental problems caused by gasoline engines.
This review is based on testing and use of the 5 HP model. The 2.5 HP model can be expected to perform similarly at its power rating.
Specifications of Lehr 5 HP Outboard:
- 15-inch short or 20-inch long shaft
- Displacement: 112 cc
- Weight: 49.6 lbs (short), 52.8 lbs (long)
- Gear shift: forward-neutral-reverse
- Manual pull start
- No-choke carburetor
- Fuel tank: 16.4 "camping bottle" propane or external propane tank
Features and Advantages
- Starts easily when cold or warm without a choke
- Eliminates problems of gasoline with 10% ethanol (such as using preservative additives to prevent the normal degradation over time)
- No mixing of oil in gasoline (in 2-stroke outboards)
- No sparkplug fouling or engine flooding
- Convenience of using inexpensive (refillable) propane bottles inserted directly into outboard housing (or larger external tank)
- No smoke, gasoline exhaust fumes, or gasoline smells
- No need to filter fuel
- Propane is readily available and generally cheaper than gasoline
- Fewer harmful emissions - better for the environment
Testing and Review
Purchased in the box, my 5 HP needed only crankcase oil to be added. I screwed a standard Coleman propane bottle into its fitting in the casing, and the motor started right up on the second pull (later in use, it always started on the first pull once the propane had pressurized the system). It was as quiet as any new 4-stroke I have seen and ran very smoothly at any RPM.
Since the owner's manual did not prescribe a break-in period or process, as with other new outboards I have used, I called Lehr to ask about how to properly break in the engine. (Typically you run a new outboard at lower RPMs for a certain number of hours to break it in.) They told me no special break-in was required because every outboard has been sufficiently run-tested at the factory before shipping.
While a 5 HP outboard is often used to power a dinghy or small aluminum boat, I tested mine on a 19-foot sailboat, the West Wight Potter 19. This boat weighs 1225 lbs and has a maximum hull speed of about 5.5 knots. The Lehr 5 HP easily pushed it along at 5 knots at a fuel-efficient half-throttle or less. This outboard can be expected to power any craft as well as any 5 HP gasoline outboard.
Others have reported that the engine can power a 12-foot aluminum skiff at about the same speed, with a half-throttle fuel consumption as high as 24 mpg. At full throttle, as with a gasoline outboard, fuel efficiency drops radically, as low as 3 mpg.
I have been very impressed with the functioning and ease of use of this Lehr outboard and have experienced no problems whatever in its first season of use.
The Downside of Propane
Propane as a fuel has no downside, as it is both better for the environment and offers several advantages over gasoline. But the user needs to be aware of two practical issues.
First, because propane is heavier than air, the fuel should not be stored inside a boat where, if a leak developed, it could fill a closed space and become a risk for explosion. The small propane bottles are easily stored in a boat's cockpit or open space, however, and the larger marine propane tanks are built to be kept outside - so there is no reason to put it below. The owner just needs to remember this risk.
A second practical issue, particularly for boaters using the smaller camp-size propane bottles, is that it is more difficult, compared to a gasoline outboard, to estimate remaining fuel. If the bottle runs empty, it can be replaced in less than 30 seconds, but if one is alone on the boat in an area of shoals, strong currents, or other hazards, even that short time can be too long to let the boat drift unattended while changing the fuel. Ensuring you're never surprised in such a situation, however, doesn't take much effort. On my boat the 16.4 oz bottle (about one fourth of a gallon) lasts an hour at normal motoring RPM, so I can keep track of how much is left. With a simple kitchen scale I can determine, before starting up, how much fuel remains in a partly full bottle and choose to use a full one if I might encounter a tight situation. It's easy to keep several of these small bottles on board to avoid running out. And an adaptor is available for refilling most bottles from a larger propane tank , such as the standard 20 lb tank used in most home grills.
I've had no regrets since I began using the Lehr outboard - and would recommend it without hesitation. Since the propane bottles are used by many boat grills and stoves, they are readily available in many waterside and marina stores. You'd likely need to plan ahead if cruising long distances in unknown waters, but for the typical user of a 5 HP outboard, this is not an issue. And it feels good, especially as a sailor who runs the engine as little as possible, to do as little damage to the environment as possible.
If you buy a propane outboard and decide to use a larger external propane tank, be sure to get a fiberglass tank like this one.
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