Depth Sounders – Understanding sensitivity and other settings

This is a great article from Dale Ward on how to tune your sounder so you get the best picture of what’s down under.

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Firstly…. the term fish finders is a commonly used name for an electronic fishing device. I tend to steer away from using the term “Fish Finder” because it is so much more than just a fish finder. A “Depth Sounder” is used to determine the bottom depth, structure, water temperature, rock location, bottom hardness etc… All of this comes into plan when “Finding Fish” especially with the style of wild Bass fishing I do where finding the fish isn’t as essential as knowing exactly where structure is located under the water as well as the depth and temperature of the water.

There is so much to learn when it comes to understanding how a sounder works and its many settings that will give you the optimum usage. Most anglers get overwhelmed with all the settings available.

The way I tend to look at is, you spend a whole bunch of money to assist you to fish better, find fish and structure, you at least owe it to yourself to get the most out of your sounder. Yes it can be a little daunting for a beginner, and even the more intermediate users can have trouble if it’s not explained properly and broken down to simplicity.

This article will be a series of posts breaking down all the common settings of Lowrance Sounders. I will explain all those settings that many anglers have trouble understanding what they are and how they can be utilised to give your fishing a better chance through the use of your unit. Settings include Sensitivity and Ping Speeds all the way through to Chirp and Overlaying Downscan to a easier, more understanding format so you can now have the full use of your sounder at its best quality for the style of fishing you do.

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Sensitivity. Think of it as a metaphor. The metaphor I’ll refer to is a hearing aid. If you turn up a hearing aid you’ll be able to hear better but if you turn it up to far the noise will be to loud and you wont be able to determine what is said. The reason I use a hearing aid as my metaphor is sensitivity is your hearing aid, it adjusts the way you get waves back to the unit. The sensitivity on a sounder needs to be above 50 percent to view anything of recognition, so when you turn it up above 50% you’ll start to realize that the images on the screen get clearer and clearer, but there is a such thing as too much sensitivity. If you turn your sensitivity up to much it will start to blur the images again and you wont get a clear view of the bottom, structure and fish arches.

There are a few pointers you can follow, but generally it is a matter of experimenting different sensitivity settings in order to get your right image quality. Shallower water for instance will not have the same sensitivity as deeper water columns. For instance, if you are fishing in water 20 metres in depth you would not set the sensitivity at 95%, this is because the image on the sounder screen will clutter. Basically it will make all objects on the screen form together and you will not get an accurate description of what is located below your boat.

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Start by easing down the sensitivity by small increments of around 3-4% at a time.Soon you will begin to realize that the screen is beginning to clear up from the bottom.Keep backing off the sensitivity until the your bottom of the screen is completely visible and clutter free and you can begin to make out structure and fish arches. This will mean that even the smallest of bait fish will be visible as they begin to move into the transducer cone angle. They will be visible as either singular fish or schools of bait. Most of the time you will be left with a heap of clutter across the top of the screen, if you are fishing off the bottom or roughly as closer to the bottom then I would suggest putting up with the clutter on the top half of the screen or if you need the whole water column I would suggest clearing up the top half of the screen using your surface clarity function in which I cover on how to use this setting below.

As you begin to fish deeper depths of water repeat the process for the optimum setting for that depth of water column.

You will find that if you make your sensitivity higher than generally you may have to, back off your contrast to give the image some depth and shadows. It really is a trial and error game as I mentioned. The more you experiment with these settings, the more it will become clear for you and you’ll wonder why you ever put it on the auto setting. Also take note that sometimes if you’re constantly changing depths in your drift it can be easier to set it to auto so you actually spend more time fishing and less time adjusting the screen.

This may take a few times to work out but you will generally begin to get the hang of how sensitivity and contrast settings work.

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Surface Clarity

Now if your screen is clear from the bottom half of the screen upwards and your top half of the screen is cluttered and you generally want to fish the top half of the water column for pelagic’s or you need the whole depth of the water column, then I would suggest to have your surface clarity option set to high. This will begin to clear up the clutter in the top part of the screen giving you a clearer view of what’s in the higher parts of the column.

Surface clarity settings also helps clear up the clutter closer to the waters surface caused from boat wake and wave actions. Bilge pumps and engine vibration can also give you clutter on the surface and interfere with image quality. If you are experiencing these problems then I would suggest turning your surface clarity to a higher setting. You’ll end up getting a much clearer image on your screen to a point that if you are fishing vertically you will see your lure as you drop it passing through the transducers cone angle. This is really fun, you now have a fully functioning sounder that is set up to now play a game of cat and mouse chasing to literally get the fish to react to your lure on screen and work out a tactic that gets them to bite.

A big variable factor to remember is personal preference is often just an anglers own makeup. Some of us, like me, were not blessed with good eyesight and this is the reason some shades and colours are better for an angler like myself but may not be better for the next angler. The more colours that are displayed in my opinion, the more detail you will be likely to see. Different colours displayed represent different shades and depths of objects with the right tuned settings. I find myself using, (but not restricted to) the colour palette 13 with a brown bottom due to its simplicity and ease of viewing.

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Ping Speed/Noise Rejection

When we cruise from hole to hole or trolling at higher speeds than normal I would recommend turning the “Ping Speed’ in settings up. That makes the transducer distribute more sound waves to echo from its target back to the transducer. When travelling at higher speeds, sometimes bait fish or a small bait school can appear on the screen as a dot when travelling at say 30-km/h. When the ping speed is turned up these targets would give off more solid return sound waves back to the unit and return a more definitive image that makes the appearance on the sonar screen more recognizable.

Changing the ping speed also changes the scroll rate of the sonar chart. Changes in the ping speed should only be made to provide the best possible image on the chart sonar screen at the time of your application. In other words don’t turn your ping speed up unless it actually helps you get a better visible image of the sonar. To get the best possible use out of your sonar chart, the details should be recognizable. It is sometimes necessary to try different ping speed settings over some known targets and stretches of waterways in which you are completely familiar with to better understand how some ping speed changes can effect your sonar chart.

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Another known issue that may rise with image interference is sometimes some boats can give off what is known as “Noise” which can be a series of clutters and interference in image quality given off from your boats engine idle or passing boats. In some cases other electronics such as live wells and bait tanks can also give off noise on the sounder screen. You can do one of two things: Turn the ping speed down or you can turn your sonar chart noise rejection on. By doing this in most cases illuminates or helps reduce noise and interference cause from other sources like an electric motor and or live wells.

Dale Ward

About Dale Ward

Dale Ward grew up in both Sydney and Country Victoria and has fished as far back as he can remember. Dale has found himself casting lures at both freshwater and saltwater species along the East-Coast and prides himself as a new member of the Kaydo Fishing World team.


Previous Offshore Tactics – Float Lining
Next Understanding Structure Scan HD Sounders

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