In 2003, Orbital tested 10 two-stroke, 15-horsepower Mercury outboards, which are fairly typical of the outboards for the bigger inflatables currently popular among serious cruisers. The problems they found with carefully formulated 10-percent ethanol blends (more on this point later) were generally limited to intervals of low (trolling) speeds and to instances of wide-open-throttle acceleration after extended periods of low-speed use. Stalling and misfires were more common under these conditions than when nonblended unleaded gasoline was used. Orbital research found that adding ethanol to gasoline increases the available oxygen for the combustion process but that the engines will tend to run lean, with the fuel affecting "cold-starting, hot-operation, cold-operation, and wide-open-throttle performance." Clearly, however, such problems can generally be corrected by adjusting the rich/lean mixture on the engine.