How the weather influences on motor power
All those who came out in their inflatable boat into the water at different times of the day noted that their boats behave differently, not as they were expected. Early in the morning the boat is almost “flying”on the water but the higher the sun and the hotter the day the less power remains in the motor and the lower its efficiency. Such a behavior of your boat has simple logical explanation.
Let’s start with the fact that most manufacturers of outboard motors are oriented to the international ISO standards. So, all manufactured products should be consistent with these standards. Before sale the boat passes a series of tests, including testing under different weather conditions.
The ISO 3046 standard requires that the calculation of the engine power is produced by means of a dynamometer at a relative humidity of 30%, a temperature of 25 ° C and a pressure Pa 100270.9783. And if the figures change, the engine power and performance changes too!
Summer time, with its high temperature, low barometric pressure and high humidity, decrease the motor power. It leads to decreasing of the boat speed, sometimes by 3-5 km/hour. There’s nothing can be done with it, so just be patient. And remember that dry and cool weather is the best friend of your boat.
Besides the weather, there is one more, smaller reason of motor power decrease. In spring time when you start preparing your boat for the coming season, you install the screw, which allow reaching the recommended speed at full power. But during the hot summer, motor power is decreasing and the screw becomes too heavy for the same motor and the same boat. So, the motor cannot reach the recommended speed.
We can agree that power decrease caused by improper size of screw leads to decrease of the boat speed. Fortunately, such speed decrease can be compensated by replacing the screw with the smaller one and motor will be able to reach the recommended speed.
The boat owner shall control replacement of the screw depending on weather conditions. In such case, the motor will perform its best power. Besides that, it will prevent the motor from destroying detonation and improve general motor efficiency.