96 GPSMAP® 4000/5000 Series Owner’s ManualSonar1. Measure the keel offset, based on the location of the transducer:• If the transducer is installed at the waterline, measure the distance from thetransducer location to the keel of the boat.Enter this value in step 3 as a positivenumber.• If the transducer is installed at the bottomof the keel, measure the distance from thetransducer to the water line. Enter this valuein step 3 as a negative number.2. From the Home screen, select Configure > MyBoat > Keel offset.3. Enter the keel offset measured in step 1:• For the GPSMAP 4000 series, use the Rocker or the Numeric Keypad to enter the distance measuredin step 1. Ensure that you enter a positive or a negative number based on the location of the transducer.• For the GPSMAP 5000 series, use the on-screen keyboard to enter the distance measured in step 1.Ensure that you enter a positive or a negative number based on the location of the transducer.4. Select Done.Setting the Water Temperature OffsetYou must have a water-temperature sensor or a temperature-capable transducer.The temperature offset compensates for the temperature reading from a temperature sensor.1. Measure the water temperature using the temperature sensor or temperature-capable transducer that isconnected to the chartplotter.2. Measure the water temperature using a different temperature sensor or thermometer that is known to beaccurate.3. Subtract the water temperature measured in step 1 from the water temperature measured in step 2.This is the temperature offset. Enter this value in step 5 as a positive number if the sensor connected to thechartplotter measures the water temperature as being colder than it actually is. Enter this value in step 5as a negative number if the sensor connected to the chartplotter measures the water temperature as beingwarmer than it actually is.4. From the Home screen, select Configure > My Boat > temp offset.5. Enter the temperature offset calculated in step 3:• For the GPSMAP 4000 series, use the Rocker or the Numeric Keypad to enter the temperature offset.• For the GPSMAP 5000 series, use the on-screen keyboard to enter the temperature offset.6. Select Done.Adjusting the Transducer SettingsNote: These features are available only on the GSD 24 and GSD 26.1. From the Home screen, select Sonar.2. Select a sonar view.3. Select Menu > More > installation.4. Select one or more options:• Select transmit Rate to help reduce self-interference. You can increase the transmit rate to speed upthe scroll speed, but this might also create self-interference.• Select transmit Power to reduce transducer ringing near the surface. Lower the Transmit Power toreduce the ringing.• Select Filter Width to define the edges of the target. A shorter filter will define the edges of the targets.Longer filters will create softer target edges, but may reduce noise.• Select transducer Diagnostics to view details of the transducer.Transducer at the waterlineA (+) positive numbershows depth at the bottomof the keel.Transducer at the bottomof the keelA (-) negative numbershows depth at the surface.Keel Offset