Mercury Pro XS 115 Outboard

Mercury Pro XS 115 Outboard. Horsepower is simply torque times rpm, Mercury vice president of product development. “As long as the torque curve is still climbing, if we add rpm, we get more power. And the 2.1-liter makes plenty of torque.”

With an extra 300 rpm, boaters can go down one propeller-pitch increment and gain acceleration with no loss of top speed, or they can run the same prop and go faster. Mercury says the 115 Pro XS is about 1 mph faster compared with its 115 Four Stroke.

The 115 Pro XS comes in 20- or 25-inch shaft lengths and either the standard 4.2-inch-diameter gearcase with a 2.07-to-1 ratio or a 4.9-inch Command Thrust gearcase with a 2.38-to-1 ratio. The Command Thrust case accommodates props up to a 16-inch diameter and produces more lift, which can improve perform­ance, though it also creates more drag, so faster boats may perform better with the 4.2-inch case. These options plus the wide selection of Mercury props make it possible to really dial in performance.