Around 2005, a new generation of four-stroke outboards reinvented marine propulsion. Virtually eliminating noise and smoke, and offering exceptional fuel economy, these high-horsepower four-strokes became smart alternatives to inboard engines. Advantages like more cockpit space, the ability to run in shallower water, and less corrosion made them the new darlings of the small-boat world. Fifteen years later, outboards are now common on much larger yachts. Not only are four and five outboards hanging off the transoms of 50-foot-plus center-console boats, but horsepower sizes have grown from 200 in 2005 to 627 on a state-of-the-art outboard by Seven Marine. Outboards are also showing up on yacht designs that previously wrote them off as ugly motors of the masses. Here are five of the best.