Raymarine Autohelm ST3000, Руководство пользователя

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Chapter 6: Adjusting Wheel Pilot Settings 65
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Calibration Level 9: Magnetic variation
Use Calibration Level 9 to input the level of magnetic variation
present at the boat’s current position.
• -ve variation = west
• +ve variation = east
The wheel pilot transmits this value onto the SeaTalk bus, so it can be
picked up by other SeaTalk instruments.
Calibration Level 10: Heading error correction
Use Calibration Level 10 to switch on Northerly or Southerly heading
error correction:
• 0 = Off
• 1 = Northern Hemisphere, 2 = Southern Hemisphere
You might notice that the autopilot tends to be a little less stable on
Northerly headings in the higher latitudes of the Northern hemisphere
(or Southerly headings in the Southern hemisphere).
This is caused by the increasing angle of dip of the earth’s magnetic
field at higher latitudes, which has the effect of amplifying rudder
response on Northerly (Southerly) headings. This error affects all
magnetic compasses and gets worse further away from the equator.
With heading error correction switched on, the wheel pilot can
compensate for this error by automatically adjusting the autopilot
gain (depending on heading). This will provide precise course
keeping on all headings.
D3263-2
North
without
compensation
North
with
compensation
81194_1.book Page 65 Wednesday, July 25, 2001 12:10 PM