New Gear Ratio for Mercury Racing 300R

The 300R outboard will be offered with a new Sport Master 1.60:1 gearcase.

New Gear Ratio for Mercury Racing 300R
According to Mercury Racing both single- and multi-engine applications may realize an improved propeller efficiency with the new 1.60:1 gear ratio.Courtesy Mercury Racing

Mercury Racing has announced that a new 1.60:1 rear ratio will be available for its 4.6L V8 300R FourStroke outboard equipped with the Sport Master gearcase. The 300R debuted in 2018 with a 1.75:1 ratio in the Sport Master, Torque Master and 5.44 HD gear case options.

Mercury Racing applications engineer Nick Nida told Speed on the Water that an MTI 340X catamaran used by Mercury Racing as a test platform at its Lake X facility in Florida reached a top speed of 115 mph with a pair of the 300R/Sport Master 1.60:1 outboards on its transom, a gain of 2 mph compared to the 1.75:1 ratio on the same boat. Not only was the speed increased without a change in drive height, the boat’s balance was improved, according to Nida.

“The 1.6:1 ratio also will allow for use of more non-cleaver propellers,” he said. “With MAX5 props, for example, we’ve seen 10- to 11-percent slip and a top speed of 110 mph.”

Mercury Racing 300R outboard engines with 1.60:1 gear ratios will begin shipping in May 2019. Conversion kits also will offered for owners of 300R outboards with the 1.75:1 gear reduction.