Using Your Electronics

By William D. Anderson

Fishermen have many tools at their disposal these days that makes finding fish a whole lot easier. The most popular are obviously fish locators.There are literally hundreds of models to choose from and they all have different features. Yet despite the prevalence of electronic fish finders today, many anglers do not take the time to learn how to use their electronics properly.
 
Fish locators use SONAR which is an abbreviation for Sound Navigation and Ranging to display depth and other information. The unit sends out a signal through a transducer mounted either inside the hull or on the transom. That signal is then bounced off the bottom and any other object in the water, then returned to the transducer and sent back to the unit where it is processed into information that anglers can use.
 
The one feature that all fish locators have in common is that they will tell you what depth of water you are in. This is also one of the most important features because you can use it to avoid hazards and to find drop offs and other structure that fish will relate to. Some units have alarms that you can set to tell you when you are over a certain depth.
 
The most common problem that fishermen encounter with depth readings is that the reading will disappear or read incorrectly. In shallow water you can sometimes fix this by adjusting the sensitivity of the unit. If your locator has trouble displaying a depth reading at high speeds, more often than not you can solve this problem by adjusting the angle of the transducer. Some transducers are not designed to work at high speeds and will only function properly at slow or moderate speeds.
 
Accompanying the depth reading is usually some type of display that shows the bottom as either shades of gray of different colors. By interpreting the color or shading, an angler can determine how hard or soft the bottom is, and from that information you can sometimes determine its content. For example, the thicker or darker the bottom line, the harder content. If you are familiar with what type of bottom content certain species prefer, this can help narrow your search. With color units, you can sometimes see fish sitting on the bottom. They might show up as a yellow smudge on the blue bottom line depending on the brand.
 
On a typical fish finder, fish are supposed to show up as arches on the display. In the real world, this is not as common as user manuals and demonstration modes would lead you to believe. For an arch to appear, everything has to be perfect. This includes the transducer angle, boat speed, and the amount of time the fish stayed in the cone. Sometimes an angler will see arches in one body of water, and when he moves to another body of water the fish will show up as dots or short lines. Fish sitting on the bottom may show up as a variance in shade or color.
 
Many times a large �cloud� will appear on the screen. This can be a school of fish, most often baitfish. If game fish are present under the school, they can be hard to detect. Once again, look for darker shades or color variances at the bottom of the cloud, or look for the lines or arches.
 
Flasher units don�t display any type of graphical information. All you typically see are colored bars of light that show up around a circle, and by watching how thick the bars are or their color; you can determine if the bar indicates a fish. Ice fishermen typically use these types of locators. You can see your bait show up as a bar, and when a fish comes up from the bottom to take it you will also see a bar that represents the fish rise to meet the bar that represents your bait. When the two meet, set the hook.
 
Forward looking sonar units can help you spot objects in the water ahead of you. They can also alert you to shallow water that is coming up and give you the opportunity to slow down. These units can show you a top to bottom scan or side to side scan of the water in front of you. While not as popular as other types of units, these can be extremely useful in finding and tracking a school of moving fish. Some of these types of units also may require more than one transducer.
 
Side Imaging or Side Scan sonar units offer a 3D view of objects below the surface on either side of your boat. The graphical display provided by some of these units can be amazingly detailed and clear which is my many law enforcement and emergency services agencies are now using them for search and rescue efforts.
 
Fishermen can use these units to see a much more detailed view of the underwater environment. One can find structure that would not otherwise be visible with a typical down-looking fish locator. Submerged trees and other structure show up in detail as do many other types of fish holding structure. In many cases, individual fish can also be spotted.
 
Learning how to use Side Scan sonar takes a little bit of patience. The transducer angle must be set correctly and the boat must be traveling at the optimal speed to get the best performance out of these units. Moving too fast or two slow will result in a distorted view of objects and many fish will be missed completely. Because you are still bouncing a signal off an object underwater, shadows will also appear behind objects that result from a lack of reflected signal. Learning to interpret these shadows will also help give you a clearer picture of what is really down there. Shadows can help determine how high an object sticks up, and also reveal more of the objects actual shape.
 
Side Scan units allow fishermen to see more structure than traditional units, and allow anglers to cover the water they fish more effectively because they are not casting towards non-productive water.
 
Other types of fish finders will display a 3D topographical image of the bottom. These units send multiple signals out and process the returns to give you a view of the terrain below your boat. They can identify fish and show precisely where the fish are located. Different icons will show up on the display to represent the size of a fish, and where it was located in relation to the transducer.
 
Many of the types of units mentioned also include what is called Real-Time-Sonar (RTS). This is usually a bar on the right side of the screen that shows the real time sonar returns. By learning to interpret these, you can start to get a very accurate idea of what is below you. Some models display this information by simulating a flasher unit display. The disadvantage to real time sonar and flasher units is that there is no record of the sonar return. However, because the returns are in real time, you are seeing an accurate picture of what your locator sees. You must learn to interpret it.
 
On traditional units, the return scrolls off the screen from right to left. It is important to remember that you are looking at sonar returns and not an actual picture of the bottom. Once you understand this, you will be able to use your fish finder much more effectively.
 
Because there are so many brands of fish finders with so many different features, it is very important to study the owner�s manual and master what the different returns will look like on the display. Once you have this knowledge you will be able to easily interpret the display and know exactly what is under your boat. This will allow you to determine what is productive water and what is non-productive water.
 
Once you have found productive water, many locators will allow you to mark it and use the built in GPS functionality to return to the exact spot at a later time. You can also create several of these �way points� to mark a drop off or creek bed that does not follow a straight line. When you return to it you can easily follow it again by watching your boat position on your screen.
 
If you are adding a second locator to your boat, make sure that the signal sent out by your existing one will not interfere with the new one. Some units can interfere with each other and cause false readings or noise to be displayed on both screens. Make sure the units use different frequencies. If they are the same, make sure that you can switch between them.
 
So the �Bottom Line� on locators is that you should read your owner�s manual very thoroughly. Make sure you completely understand all of your locator's functionality and most importantly how the sonar returns will be displayed on your screen. The picture you see on the screen is not always a representation of the environment below. If you are shopping for a new locator, do your research and find one that has the features you require. Most are easy to install, but if you�re not comfortable drilling holes in your boat, have a professional do it.