Boat

1. A boat comprising:

a boat propulsion unit mounted on a hull in a rotatable manner;

a boat propulsion unit operation controller disposed in the hull to be steered by an operator;

a steering motor to steer the boat propulsion unit based on steering control of the boat propulsion unit operation controller;

a signal cable to electrically connect the steering motor and the boat propulsion unit operation controller;

a steering load detector to calculate a necessary output value of the steering motor required to steer the boat propulsion unit in a traveling state;

a motor output detector to detect a possible output value that can be output by the steering motor;

a prediction determination unit to compare the necessary output value from the steering load detector with the possible output value from the motor output detector; and

an electric power load controller to control a battery charge amount to be increased and/or to control an electric power load to be reduced when the necessary output value is determined to be larger than the possible output value by the prediction determination unit.

2. The boat according to claim 1 , wherein the steering load detector calculates the necessary output value from at least either one of:

a traveling state including respective states of speed and magnitude of engine rotational speed, magnitude of acceleration, thrust, a trim angle, weight, and/or a waterline,

a steering state including respective states of a rudder angle, speed, acceleration, or steering operation,

a state of the boat propulsion unit including the number of outboard motors, a mounting position of the boat propulsion unit, a propeller opening direction, a propeller shape, a trim tab setting, a height and length of a transom of the boat, and/or the presence or absence of, or a state of, an add-on cavitation plate, or

the steering motor drive state including responsiveness of the steering motor determined by deviation and gain, the number of the steering motors that are driven, temperature of the steering motor, temperature of a motor drive circuit for the steering motor, a fault or lock or a short circuit for the steering motor, and/or a voltage supplied to the steering motor from the battery.

3. The boat according to claim 1 , wherein the motor output detector detects the possible output value from any one of a battery voltage, a battery current, a steering motor temperature, a steering motor fault state, or a number of boat propulsion units that are driven.

4. The boat according to claim 1 , wherein the electric power load controller controls at least any one of a number of driven engines of the boat propulsion unit, driving of the trim, driving of an engine starter, engine rotational speed, a number of batteries that are connected, or a number of electric generators that are driven, and increases electric power to be supplied to the steering motor to be larger than a current state of electric power available to the steering motor, so that the possible output value is increased.

5. The boat according to claim 1 , wherein the electric power load controller reduces the electric power load of electric apparatuses on the boat excluding electric power used by the steering motor, and to increase electric power to be supplied to the steering motor to be larger than a current state of electric power available to the steering motor, so that the possible output value is increased.