readings are not exact. If the transducer is 1 foot below the surface, and the screen shows the water depth as 30 feet, then the actual depth is 31 feet.
On sailboats or other large vessels with deep drafts, the distance between the transducer and the keel or lower engine unit can be several feet. In those cases, an inexact depth reading could cause your vessel to strike underwater structure. The Keel Offset feature eliminates the need for the navigator to mentally calculate how much water is under his keel.
Keel Offset lets you calibrate the digital depth: chart depth scale, chart cursor depth and fish symbol depth displayed on the screen. To calibrate the depth indicators, measure the distance from the face of the transducer to the lowest part of the boat. In this example, we will use 3.5 feet. This will be entered as a negative 3.5 feet, which makes the depth indicators perform as if the transducer is lower in the water than it really is.
1.Press MENUMENU↓ to SONAR SETUPENT.
2.Use ↓ to scroll down to KEEL OFFSET, then press ENT. The Keel Offset dialog box appears. Press ↓ to change the plus (+) sign to a minus
3.Press → to the first number, then press ↑ to change the number to 3.
4.Press → to the second number, then press ↑ to change the number to 5, then press EXIT. The depth indicators now accurately show the water depth beneath the keel.
NOTE:
If knowing the exact depth of water beneath the keel is less important, you can calibrate the depth indicators so they show the actual water depth from surface to bottom. To do this, measure the distance from the face of the transducer to the surface (the water line on the boat). In this example, we will use 1.5 feet. This will be entered as a positive 1.5 feet, which makes the depth indicators perform as if the transducer's higher in the water than it really is.
1.Press MENUMENU↓ to SONAR SETUPENT.
2.Use the ↑ ↓ keys to select SET KEEL OFFSET and press ENT. The Keel Offset dialog box appears with a plus (+) sign at the front of the box.
3.Press → to the first number and use ↑ to change the number to 1.
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