5 Things to Consider while Using Autopilot Systems on Ships
In the good old days of merchant shipping, the Quartermaster was a vital member of the Bridge Team. "Quarter master" was the title given to strong sailors whose primary responsibility was to steer the ship according to the orders of the master and officer. The quarter masters kept watches and took turns driving throughout the day when they were at sea.
The notes below are a brief summary of five important points to be taken into consideration while operating the on-board autopilots for boats for safe and smooth navigation.
1. Turn Rate and Rudder Limits
The rotation method is one of the most important controls in the self-driving system. The system will use the selected turn method to make adjustments to the course. The limit of these rotation methods can be entered by the user, which is as follows
a. Turnover Rate
This is the most commonly used method of rotation. In this method, the user can set the value of rotation rate between 1-300 degrees (varies on different models). When turning, the rudder will move as much as necessary to reach the desired rate of turn without exceeding the set value. The officer must take into consideration the maneuvering characteristics of the vessel and establish a safe value for the vessel.
B. Rudder limits
The rudder limit method allows the user to set a value from 1 degree to the maximum rudder angle. In this method, while changing course, the rudder will not exceed more than the specified limit. Again, the maneuvering characteristics of the vessel should be taken into account when selecting the rudder value.
Modern systems also allow rotation by radius. In this method user can enter turning radius in nautical miles.
2. Steering Gear Pumps
Steering gear pumps are used to pump hydraulic oil to operate the steering gear unit (RAM) which in turn moves the rudder in the desired direction. This means that when more pumps are running, the rudder will move faster. The number of available pumps varies according to the steering gear unit.
The watch officer must be aware of the pumps and use them wisely.
If the autopilot is operated in high traffic areas that require sudden and rapid adjustments, the maximum power steering gear pumps must be operated.
On cruises and open sea navigation with less traffic, operation of the pumps should be kept to a minimum.
3. Off-Track Alarm
The course deviation alarm is used for the purpose of notifying the operator in the event of any discrepancy in the specified course and the actual heading of the vessel. The user can manually set the amount of degrees required, after which an alarm will sound informing the user that the specified difference degree has been exceeded.
However, the user must check for course changes as in some cases when the gyro compass wanders off course, the autopilot will follow the gyro compass and fail to issue the alarm.
4. Traffic Density
It is not recommended to use Auto-Pilot when navigating in high traffic areas, narrow channels, traffic separation systems and other restricted areas. The autopilot may not be effective enough to turn the vessel automatically while navigating such areas that require quick adjustments and maneuvers to avoid a collision or close quarter condition. If the autopilot is used in such situations, all steering gear pumps must be operated for better rudder response.
5. Speed
The system operates inefficiently at low speeds. It is not recommended to use the autopilot when the vessel is maneuvering or moving at a very low speed.
The system allows users to sync with the speed log to receive a feed on the vessel's speed. Users should check the speed log as any error in the speed log will be reflected in the automatic driving system.
The system also allows users to enter speed manually, and when doing so, it is important to set a value as close as possible to the actual vessel speed.
Conclusion
As previously mentioned, autopilot is an undeniable boon to modern navigation. It is the responsibility of officers to ensure that they are fully familiar with the equipment, its features and controls to use it properly and effectively. Although autopilot systems vary in model from one ship to another, their operating principle and features will be the same. Deck officers using the equipment are strongly advised to read the manufacturer's operating manual to gain a thorough understanding of the equipment.
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