Читать книгу SELF-STEERING UNDER SAIL - Peter Foerthmann - Страница 18

(Example: Autohelm 6000/7000)

1. The Rudder Gain, which has 9 settings, specifies how much the rudder should be moved to return the boat to a desired course. Oversteering will result if the angle is set too high, understeering if it is set too low.

2. The Rudder Damping function has 9 positions and serves to damp yawing motions.

3. The rudder amidships position in the rudder reference transducer has an adjustment range of -7 to +7 degrees.

4. The Rudder Limit function prevents the autopilot reaching maximum lock at full power, which could cause mechanical damage.

5. Boat Turn Rate determines how quickly the boat turns when the autopilot makes course corrections.

6. The autopilot can be set for an average Cruise Speed of anywhere between 4 and 60 knots (sailing boat or powerboat).

7. The adjustable Off-Course Alarm sounds when the vessel’s course deviates from the desired course by more than a set maximum (in degrees) for longer than 20 seconds.

8. There are four Trim settings. This function controls the additional rudder movement necessary to counter off-centre thrust (e.g. when operating a propeller mounted to one side, only used when motoring).

9. The Joystick has two settings, but these are not particularly relevant for sailing boats.

10. The control unit can be set for linear or hydraulic drive.

11. The response angle function has 9 positions. It ensures that the response of the autopilot is appropriately delayed if there is slack or play in the steering system.

12. Compass deviation taken from a chart can be input.

13. The adjustable Northerly/Southerly Turning Error Compensation feature is used in areas where the orientation of North is uncertain to ensure the compass receives an accurate signal.

14. There are three settings for the reaction speed of the autopilot; the higher the value set, the greater the steering precision and, consequently, the power consumption.

All the functions mentioned are initially set at the factory. They can all be adjusted on board and it is essential that they are individually matched to the characteristics of the vessel.

To summarise, each model of autopilot gives a certain level of steering performance which is dictated by its range of technical features and which cannot be improved. All that is left once the autopilot is correctly set up is to increase the time between steering corrections, and hence save power, by ensuring the boat is balanced and the sails are properly trimmed. It should be obvious that selecting a greater degree of steering accuracy will lead to more frequent rudder movements and increased power consumption.