America's Definitive Marine Engine Magazine
by Timothy P. Banse
Anyone who has spent time holding the tiller handle of a small outboard will be pleased to learn of Mercury Marine's 5-horsepower propane-fueled, four-stroke outboard. Personally, I used to live anchored out in the Florida Keys aboard my sailboat, and ferried between Itxaso and shore in a dinghy to fill 5-gallon water jugs, get groceries and dispose of trash. More than once I had to row because a slug of water contaminated the gasoline and the engine refused to start. Or, gum in the gasoline clogged up the carburetor jets. With propane though, instead of being burdened with 87 octane, I could have thrown away my water-separating filter funnel and attached either a one-pound tank of propane, or a 20-pound/5 gallon tank. Either size would have obviated the frustration of junk fuel.
Beyond the gasoline versus propane issue, how's this outboard rate in the real world? Let's visit upon the details. No big surprise, being a 5-horse, it is lightweight At a mere 59.5 pounds (27.2 kilograms). It is eminently easy to transport and to wrangle onto the transom of a hard shell dinghy or inflatable. Displacing a whopping huge, 7.5 cubic inches (123cc) of displacement (displacement is relative), the motor boasts a true 5-horsepower. Sometimes you're in a hurry to get to Sundowners and dinner at the dockside bar and grill.
This 5 horse tyke burns the same propane as a backyard grill or Coleman camp stove. Which in turn means there's no need to haul a gallon can of gasoline and suffer the indignity when it splashes in your trunk and stinks up the car for a month. And because propane doesn't degrade or contain ethanol like 87 octane does, there's no worries about what type of fuel to run, or how fresh or stale it is. Neither do you have to spend extra for fuel stabilizers or water zorb. Perhaps most notable, compared to gasoline, propane engines emit about 30-percent lower emissions.
Starting is quite easy. The pressurized fuel system eliminates priming. Its manual choke enriches the fuel-to-air ratio for fast and reliable starts, particularly when the engine is as cold as a stone. Similarity, the auto decompression reduces pull force needed when yanking the starter rope.
This outboard comes standard with a propane auto shut-off valve on the engine and also in the fuel hose connector. Its 6-foot (1.8-meter) fuel hose fittings thread quickly and easily to the outboard and include a standard US POL connector on the tank side. How about fuel economy? Drawing form a conventional 20-pound (5-gallon) tank of propane, an engine running at wide-open throttle lasts about six-hours. Throttling back extends running time proportionality longer.
The shift lever is easy-to-reach. There are six tilt positions with a shallow-water drive. An integral reverse-thrust exhaust relief and high-thrust propeller improve slow-speed handling and control. For running lights and minimal electronics, a 12 Volt, 4 Amp/50-Watt alternator replete with cable, allows charging a battery.
|Mercury 5 Horse Propane Outboard||Specifications:|
|Engine Type||4-Stroke OHV|
|Cylinder Configuration||1 Cylinder|
|Bore & Stroke||2.32 x 1.77 Inches|
|Full Throttle RPM Range||5,000 - 6,000|
|Cooling System||Water Cooled|
|Ignition System||Digital CDI|
|Fuel System||Propane Mixer|
|Fuel||HD-5 (65% Propane or Greater)|
|Exhaust System||Through Pro|
|Gear Ratio||2.15 to 1|
|Propeller||3 Blade -Aluminum|
|Transom Height||15 Inches|
|Consumer Warranty Term||3 Years|