B&G Hydra 2000, User Manual

Page: 77 / 147

Hydra 2000 User Manual
Part 3 - Calibration
HB-0844-02
3-21
If the wind direction is higher on port tack than starboard
tack, ADD HALF the DIFFERENCE in readings between the
two tacks to the true wind angle.
The converse will apply:
If the wind direction is lower on port tack than on starboard,
SUBTRACT HALF the DIFFERENCE in the readings between
the two tacks, to the true wind angle.
This method is used when tacking upwind, gybing downwind or
tacking reach to reach.
The correction value at each point in the table is entered into the
Hydra 2000 memory. The true wind correction facility, is then
found in the menu by:
WIND
→ →
TRUE W/A, CALBRATE
→ →
CORRECTION
Using Scroll Up or Scroll Down until the one required value to be
corrected is found. In this example it would be "upwind, 10 knots".
Having scrolled through to this, press the
Enter Key. This will
allow entry of the required number of degrees correction (i.e. +5).
Use the
Scroll Up and Scroll Down Keys to increase or
decrease the value accordingly.
Pressing the Enter Key sets this figure in the Hydra 2000
memory.
At initial calibration it is important to enter the same value of
correction to the wind speeds either side of the one you are using.
This is to avoid the true wind direction jumping in value when the
wind speed drops or increases outside the range you are
correcting. When the table entries approach completion it will be
possible to enter individual changes as other corrections will be
accurate enough to avoid any strange "step" changes as the true
wind speed varies.
It is very important to enter all these corrections into a Calibration
Chart. In this way any large gaps in the correction table will be
noticed where no entries have been made.
3.6.2 True Wind Speed Calibration
True Wind Speed suffers from another, mainly aerodynamic
problem, where it tends to over-read downwind because of
accelerated airflow over the top of the mast. It is possible to