Your two-stroke gasoline outboard is an especially heavy polluter. According to estimates, a 70-horsepower, two-stroke gasoline outboard emits the same amount of hydrocarbon in one hour as a new-model car does driving nearly 5,000 miles.

Canada's Environmental Technology Centre compared two-stroke outboards with four-strokes and found that two-stroke outboards create 50 percent more carbon monoxide, 15 times more unburned hydrocarbons, and five times as much oil and grease.

It’s time for a change.