Part of that performance comes from a standard hot rodder's trick: big engine, light boat. Tipping the scales at 2,838 pounds and powered by MerCruiser's 220-horse 5.0-liter V-8, the 2150 flat out scoots across the water to a top speed of better than 50 mph. Throttle back to about 75-percent throttle and the 2150 cruises easily at 37.9 mph. At that speed, the engine is just purring along, barely huffing at all. And it's quiet, too. At 36 mph, our sound meter registered a paltry 85 decibels from the driver's seat. To put that in perspective, that's only three decibels higher than Cobalt's 226, the quietest boat we've ever tested.