Parker 2014 - Performance Factors; Engine Efficiency

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performance
PERFORMANCE FACTORS
Maximum performance is dependent on many factors and cannot be guaranteed. These factors will vary with changing conditions. Some of
these factors are listed below.
ENGINE EFFICIENCY
Engines operate most eciently at the RPM conrmed in the engine operating manuals, assuming your boat is equipped with the correct
engines, the engines are properly tuned and the drive systems are in good condition. Eciency will decrease if normal care and maintenance
is not performed. If engines are neglected, power will drop and speed will decrease. In addition, expensive repairs may become necessary. Be
sure to follow all instructions in the engine operation manuals.
WEATHER CONDITIONS
Weather conditions aect engine performance. Barometric pressure and humidity both inuence horsepower. A change of weather could
cause a 10% loss in horsepower on some hot days.
LOAD DISTRIBUTION
A decrease in performance will be noticed when gear, equipment, passengers and fuel are added. This type of extra load will aect the
performance of the boat according to the distribution of the weight. Water accumulation in the bilge will also aect performance. Keep the
bilge dry to eliminate this problem.
MARINE GROWTH
Maximum performance is obtained only when your hull bottom is clean. Marine growth on the bottom of the boat will increase resistance
and decrease speed. These conditions will also increase fuel consumption. Bottom paint and some options may aect performance.
TRIM
Most outboard models are equipped with power tilt and trim mechanisms. The purpose of power tilt function is to raise the engine for launching,
loading or trailering your boat. The power trim function may be used to adjust the boats planing performance and running attitude. Trim refers
both to the weight distributions inside the boat and to the angle of thrust of the drive unit. The angle of thrust of the drive unit forces the bow
up or down. The proper trim angle will vary depending on the load and weight distribution in your boat. If the drive is raised too far, you could
cause the propeller to “ventilate”, resulting in a sudden increase in engine RPM and a loss of speed. If this occurs, immediately reduce engine
speed and lower the drive until the condition is corrected.