System for and method of controlling watercraft

1 . A system for controlling a watercraft including an engine, the system comprising:

a first temperature sensor to detect an intake air temperature of the engine;

a second temperature sensor to detect an engine wall temperature;

a display to display information regarding the engine; and

a controller configured or programmed to:

obtain the air intake temperature of the engine either upon an activation of the controller or a start of the engine;

obtain an engine wall temperature upon the activation of the controller or the start of the engine;

estimate an external air temperature based on the intake air temperature obtained either upon the activation of the controller or the start of the engine when a difference between the engine wall temperature and the intake air temperature is less than or equal to a threshold; and

determine an occurrence of malfunctioning or abnormality of the watercraft based on the estimated external air temperature; and

display an alert on the display when it is determined that malfunctioning or abnormality of the engine occurs; wherein

the system does not include a sensor to detect the external air temperature.

2 . The system according to claim 1 , wherein

the watercraft includes a main switch to activate the controller; and

the controller is configured or programmed to estimate the external air temperature based on the intake air temperature to be obtained upon a turn-on operation of the main switch.

3 . The system according to claim 1 , further comprising:

a pressure sensor to detect an intake air pressure of the engine; wherein

the controller is configured or programmed to:

obtain the intake air pressure either upon the activation of the controller or the start of the engine; and

estimate an atmospheric pressure based on the intake air pressure obtained either upon the activation of the controller or the start of the engine; wherein

the system does not include a sensor to detect the atmospheric pressure.

4 . The system according to claim 3 , wherein

the watercraft includes a main switch to activate the controller; and

the controller is configured or programmed to estimate the atmospheric pressure based on the intake air pressure to be obtained upon a turn-on operation of the main switch.

5 . A system for controlling a watercraft including an engine and a water pump to draw in external water to supply the engine with the external water as a cooling water of the engine, the system comprising:

a first temperature sensor to detect a cooling water temperature of the engine;

a display to display information regarding the engine; and

a controller configured or programmed to:

obtain the cooling water temperature of the engine either upon an activation of the controller or a start of the engine;

estimate a temperature of the external water based on the cooling water temperature obtained upon the activation of the controller or the start of the engine;

determine an occurrence of malfunctioning or abnormality of the watercraft based on the estimated temperature of the external water; and

display an alert on the display when it is determined that malfunctioning or abnormality of the engine occurs; wherein

the system does not include a sensor to detect the external water temperature.

6 . The system according to claim 5 , further comprising:

a second temperature sensor to detect the engine wall temperature; wherein

the controller is configured or programmed to estimate the temperature of the external water based on the cooling water temperature obtained upon the start of the engine when a difference between the engine wall temperature and the cooling water temperature is less than or equal to a threshold.

7 . The system according to claim 5 , wherein

the controller is configured or programmed to:

obtain a length of elapsed time from a previous stop of the engine to a current start of the engine; and

estimate the temperature of the external water based on the cooling temperature obtained upon the start of the engine when the length of elapsed time is greater than or equal to a threshold.

8 . A method of controlling a watercraft including an engine and a controller to control the engine, the method comprising:

obtaining an intake air temperature of the engine either upon an activation of the controller or a start of the engine;

obtaining an engine wall temperature either upon the activation of the controller or the start of the engine;

estimating an external air temperature based on the intake air temperature obtained either upon the activation of the controller or the start of the engine in response to a difference between the engine wall temperature and the intake air temperature being less than or equal to a threshold;

determining an occurrence of malfunctioning or abnormality of the watercraft based on the estimated external air temperature; and

displaying an alert on a display when it is determined that malfunctioning or abnormality of the engine occurs; wherein

the watercraft does not include a sensor to detect the external air temperature.

9 . The method according to claim 8 , wherein the watercraft includes a main switch to activate the controller, the method further comprising:

estimating the external air temperature based on the intake air temperature to be obtained upon a turn-on operation of the main switch.

10 . The method according to claim 8 , further comprising:

obtaining an intake air pressure of the engine either upon the activation of the controller or the start of the engine; and

estimating an atmospheric pressure based on the intake air pressure obtained either upon the activation of the controller or the start of the engine; wherein

the watercraft does not include a sensor to detect the atmospheric pressure.

11 . The method according to claim 10 , wherein the watercraft includes a main switch to activate the controller, the method further comprising:

estimating the atmospheric pressure based on the intake air pressure to be obtained upon a turn-on operation of the main switch.

12 . A method of controlling a watercraft including an engine, a water pump to draw in external water to supply the engine with the external water as a cooling water of the engine, and a controller to control the engine, the method comprising:

obtaining a cooling water temperature of the engine either upon an activation of the controller or a start of the engine; and

estimating a temperature of the external water based on the cooling water temperature obtained upon the activation of the engine or the start of the engine;

determining an occurrence of malfunctioning or abnormality of the watercraft based on the estimated temperature of the external water; and

displaying an alert on a display when it is determined that malfunctioning or abnormality of the engine occurs; wherein

the watercraft does not include a sensor to detect the temperature of the external water.

13 . The method according to claim 12 , further comprising:

detecting the engine wall temperature; and

estimating the temperature of the external water based on the cooling water temperature obtained upon the start of the engine when a difference between the engine wall temperature and the cooling water temperature is less than or equal to a threshold.

14 . The method according to claim 12 , further comprising:

obtaining a length of elapsed time from a previous stop of the engine to a current start of the engine; and

estimating the temperature of the external water based on the cooling water temperature obtained upon the start of the engine when the length of elapsed time is greater than or equal to a threshold.