Lowrance HDS-7 Gen3 Installation Manual US - Page 37

Sonar setup

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Sonar setup The Installation page allows configuration of the internal sonar. Keel offset This is a value that can be entered on the Sonar Installation page to make depth readings relate to any point from the water surface, to the deepest point of the vessel. This value is applied to a sonar source connected via ethernet, and changes will be seen on all devices connected to the network. Below are some typical ways in which the offset is used: A) For Depth below Keel: Set the distance from transducer to the bottom of the keel - this should be set as a negative value. B) For Depth Below Transducer: No offset required. C) For Depth Below Surface (waterline): Set the distance from transducer to the surface - this should be set as a positive value. A B C Water speed calibration (sonar transducer) Water speed calibration is used to adjust the speed value from the paddle wheel to match the actual boat speed through the water. Actual speed can be determined from GPS speed over ground (SOG) or by timing the boat over a known distance. Water speed calibration should be performed in calm conditions, with minimal wind and current movement. Increase this value above 100 % if the paddle wheel is under reading, and decrease this value if it is overreading, e.g. if the average water speed reads 8.5 knots (9.8 MPH) and SOG records 10 (11.5 MPH) knots the calibration value needs to be increased to 117 %. To calculate the adjustment, divide the SOG by the paddlewheel speed, and multiply the product by 100. Calibration range: 50-200 %. Default is 100 %. Software setup | HDS Gen3 Installation Manual | 35

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Software setup |
HDS Gen3 Installation Manual
Sonar setup
The
Installation
page allows configuration of the internal sonar.
Keel offset
This is a value that can be entered on the Sonar Installation page to
make depth readings relate to any point from the water surface, to
the deepest point of the vessel.
This value is applied to a sonar source connected via ethernet, and
changes will be seen on all devices connected to the network.
Below are some typical ways in which the offset is used:
A) For Depth below Keel: Set the distance from transducer to the
bottom of the keel - this should be set as a negative value.
B) For Depth Below Transducer: No offset required.
C) For Depth Below Surface (waterline): Set the distance from
transducer to the surface - this should be set as a positive value.
A
B
C
Water speed calibration (sonar transducer)
Water speed calibration is used to adjust the speed value from the
paddle wheel to match the actual boat speed through the water.
Actual speed can be determined from GPS speed over ground
(SOG) or by timing the boat over a known distance. Water speed
calibration should be performed in calm conditions, with minimal
wind and current movement.
Increase this value above 100 % if the paddle wheel is under
reading, and decrease this value if it is overreading, e.g. if the
average water speed reads 8.5 knots (9.8 MPH) and SOG records 10
(11.5 MPH) knots the calibration value needs to be increased to 117
%. To calculate the adjustment, divide the SOG by the paddlewheel
speed, and multiply the product by 100.
Calibration range: 50-200 %. Default is 100 %.