Correct engine height is critical to getting the most performance from multi-species fishing boats running a Mercury Racing propeller. Fortunately, it’s easy to adjust the engine height of most outboard-powered boats. In this short video Mercury Racing Service Product Manager Bob Krupp and Mercury Racing Propeller Manager Nick Petersen demonstrate how to set engine height on a Lund 202 Pro V GL powered by a Mercury Racing 300R outboard, with a Mercury Racing Bravo I LT propeller. The same process will apply to any multi-species boat powered by a Mercury outboard, using the Bravo I LT propeller. High-performance bass boats will typically run best with the motor set much higher.
With Mercury outboard power, this type of boat is usually shipped from the manufacturer with a three-blade Mercury Tempest propeller and the motor set with the anti-ventilation plate about 1.5 inches above the bottom of the boat. This is a good basic set-up, but the four-blade Mercury Racing Bravo I LT prop will benefit from a higher motor position, ideally at 2.25 inches above the boat bottom. If the prop is too low in the water it will not generate maximum lift, and top speed will suffer. If the prop is too high, efficiency will be reduced at full trim and top speed.
To accurately set engine height, start with the boat on its trailer on a level surface. Use a carpenter’s level to check that the boat is level. You can use the trailer tongue jack to raise or lower the bow until the boat is level. Next, place the level on the anti-ventilation plate of the motor, and trim the motor until it is also level. Now use a long straight edge (Bob and Nick utilize a steel yardstick) to compare the engine height to the boat bottom. Hold the straight edge flush to the boat bottom and extend it back to the motor. The bottom of the anti-ventilation plate should be 2.25 inches higher than the boat bottom.
If your boat is equipped with a hydraulic or screw-type jack plate, use it to raise or lower the engine to the correct height. Motors mounted directly to the transom can be raised in .75-inch increments using the bolt holes in the transom bracket – unless you have an engine lift, ask your Mercury dealer for help raising the motor.