by Conrad & Judy Kreuter
One of the most useful aids to boating is a depth finder. From a simple in dash digital depth gauge to an advanced color fish finder, these instruments will add a margin of safety to your navigation by enabling you to see the depth of the water, bottom contours, and the location of schools of fish.
To select the best depth finder for your needs, determine which basic features you require from among the following: analog or digital depth readings only, depth readings with bottom contour, fish finding capabilities, surface water temperature, speed measurement, shallow or deep alarms, and gray or color screen. Additional advanced features are also available. Check with your local dealer to help you determine which features that you will need for your type of boating.
Depth reading only: Usually these types of depth finders fit directly into the dash instrument panel. They are good for boats with extensive instrumentation at the helm where depth readings are required.
Depth readings with bottom contour: These depth finders are slightly larger and do not fit into dash panels easily. Instead they mount on top or under the dash panel. The screen size is determined by the number of pixels or screen elements displayed. The more pixels the greater the definition and clearer the representation. As the boat moves through the water, the screen follows and displays the depth and a moveable picture of the bottom contours.
Fish finder: These depth finders display an on screen symbol when fish are present under the boat. Schools of fish can be identified easily. Some models will also display the depth at which the fish are located.
Speed and temperature: By the use of a transom mounted paddle wheel sensor, boat speed can be displayed on the depth finder screen. Temperature of the surface of the water can also be determined on these units as well. Temperature readings are important in fishing for certain type of fish.
Alarm functions: Shallow water alarms are useful when boating in unknown areas to alert the operator that the boat is heading into shallow water. Deep-water alarms can be used as anchor watches to alert the operator that the boat is drifting.
Color or gray: This refers to the presentation of the on screen data. For most applications, gray is ok, for more demanding professional applications, color will enhance details.