B&G HS2000 - Manual (Page 35)

HS 2000 User Manual
Part 2 - Operating Information
HB-0846-03
2-22
2.10.15 Tidal Set and Drift
Menu Heading: NAVIGATE
Function Text: TIDE SET or TIDE RTE
Update Rate: Once per second
Units: Degrees magnetic, knots
Notes
1. Damping 0-99 minutes.
2. Calibration: Magnetic variation.
3. Some position fixers output the current local magnetic variation on
the NMEA 0183 port using either HVD, HVM, RMA or RMC
sentences. As a result CAL VAL 1 on the TIDE SET function will
automatically set to the correct variation.
Your position fixer will either supply a true or magnetic bearing to the
HS 2000 System. If it supplies true bearing then you must enter the
magnetic variation into the HS 2000 System. It is found in the menu
under:
NAVIGATE ? TIDE SET, CALBRATE ? CAL VAL 1 (MAG VAR)
Note
If the position fixer sends magnetic bearing, check that the variation
is correctly entered into the position fixer.
The calculation involves comparing the course and speed over the
ground from the position fixer to the course and speed of the boat
through the water, from dead reckoning. Any differences are due to
the tidal set and drift and can be displayed as such. The damping on
this function is adjustable and this can be important; in rapidly
changing tidal situations you need to lower the damping down to be
able to see changes quickly; conversely, in a steady tide or current,
the longer the time over which the calculation is averaged, the more
accurate the results will be. The lag in the position fixer’s ability to
adjust to rapid changes in direction should also be taken into account
when considering the results of this function.