Outboard Engines

Outboard motors have come a long way. If you were to purchase an outboard engine prior to 2006, you would be shopping in a marketplace dominated by carbureted 2-stroke engines. In these traditional engines, the intake and exhaust ports are both open during the piston’s downstroke. They lose 20 to 30 percent of their fuel as it passes straight through the combustion chamber unburned or partially burned, releasing it directly into the water and air as pollution.

outboard, dinghy, engine

Fortunately, shifting environmental and economic concerns generated the need for an outboard engine that is both clean and cost effective to operate. The U.S. Environmental Protection Agency (EPA) enacted emission standards for outboard and personal watercraft manufacturers that were phased in over nine years (1998 to 2006). All outboard, 2-stroke and even 4-stroke, manufacturers were required to up their standards to decrease the amount of pollution released into the environment.

Here’s how some of the environmentally friendly outboards work:

Direct Fuel Injection (DFI) 2-Stroke Engine

The computerized DFI system precisely regulates the air-fuel mixture and directly injects fuel into the cylinder when the piston has risen up far enough to block the exhaust port. This prevents any unburned fuel from being blown out of the exhaust port. 

4-Stroke Engine

In this engine, the air-fuel mixture flows into the combustion chamber via intake valves, and the exhaust leaves through exhaust valves. Both valves are never open simultaneously, preventing unburned fuel from escaping the combustion chamber and entering the environment. 

Electric Engine

Electric motors convert battery power into propulsion. Even though electric engines are more expensive than other outboard engines, the operation costs are much lower. These engines are low maintenance, quiet, exhaust- and emission-free, and you don’t have to worry about fuel and oil spills. They are limited due to the weight and size of the batteries needed to support the engine. However, the batteries can be charged by solar panels, wind or water generators (see Renewable Energy for more information). Here are a few companies that offer electric outboard engines:

outboard, electric engine, dinghy

Whether you want to power your canoe or a 50-foot center console, there is a wide range of options when choosing an outboard engine. Check out Marine Engines and Power Systems by boats.com for reviews on all types of outboards.

Did you know?

  • California added two additional tiers of standards that are more stringent than the U.S. EPA’s standards (Air Resources Board).

Green Boating Guide: