Raymarine i70, Operation Instructions Manual

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5. Select the device that the transducer you are calibrating are connected to.
A list of available transducer data is displayed.
6. Select Depth
(1)
.
Important:
(1) Step only applicable to iTC-5.
7. Select Depth Offset .
8. Select Depth From: .
A list of transducer offsets is displayed:
• Waterline
• Keel
• Transducer (default)
9. Select the location that you want depth measurements to be taken from.
After selection the depth offset page is displayed. If you have selected Waterline or Keel an
offset must be applied.
10. Select Offset: .
11. Use the Up and Down buttons to adjust the depth offset to the required value.
The offset value should be the same as the measured distance:
• from the transducer face to the Waterline, or
• from the transducer face to the bottom of the Keel.
12. Select Save .
Setting an incorrect depth offset could lead to your vessel running aground.
4.3 Speed calibration
Speed transducer calibration is required as transducer performance is affected by a number of
variables such as transducer location, shape of the hull and water flow characteristics. The purpose
of performing Speed calibration is to ensure that the speed readings at the instrument are a true
indication of the vessel’s actual speed.
In order to achieve accurate results, speed calibration must be carried out in calm conditions with
zero tide and zero current.
Speed calibration aligns the instrument’s log speed (Speed Through Water) to:
• Speed Over Ground (SOG), or
• a referenced speed
Calibrating using SOG
For most installations a 1 Point Speed Calibration is all that is required.
If the 1 point calibration does not provide sufficiently accurate readings or you require a higher
level of precision for your speed readings then a Speed Run Calibration can be carried out. It is
advisable to carry out the Speed Run Calibration at as many speeds as possible. This is particularly
important for planing vessels.
(1) Conventional speed transducers have a maximum of 5 calibration speeds, and smart transducers
(e.g. DST800) have up to 8.
If required each calibration point can also have a calibration factor applied to further align the log
speed reading across different vessel speeds.
Note:
(1)
The Speed Run Calibration cannot be performed when the transducer is connected to a Speed
Pod.
Calibrating without SOG
For most installations a 1 Point Speed Calibration is all that is required. The calibration must be
performed using a way of estimating actual vessel speed and adjusting the displayed reading so that
the log speed matches the your estimated speed.
Transducer calibration 25