High chirp versus low chirp on a Simrad comes down to depth: inside 600 feet you run high chirp to separate fish from bait inshore, and outside 600 feet you switch to low chirp for offshore depths, while downscan gives a cleaner, ghostlier picture for confirming bait on the bottom. In this How 2 Tuesday I sit down with Captain Scott Walker to cover when to use each, plus how he sets gain, scroll speed, and color erase.
Listen now: press play in the player above and follow along.
Chirp is a more intense sonar signal that separates fish from bait, so instead of seeing one meatball you see the predators and the bait separately. The rule Scott uses is simple: inside 600 feet, use high chirp, and outside 600 feet, switch to low chirp. Inshore snapper fishing he is on high chirp; heading offshore for tuna or swordfish he switches the source to low at 600 feet. He walks through the settings in the episode.
Downscan gives a cleaner, ghostlier picture that marks fish as little white marks, which is useful for confirming bait that sits tight on the bottom. Scott sets up a split screen with echo, the chirp view, and downscan side by side when he is fishing pilchards on grass beds, because pilchards mark with the bottom and are hard to see. Seeing both views at once confirms what he is looking at. He shows the split-screen setup in the episode.
Scott sets gain manually first with auto turned off. He turns the gain up until the screen starts to bleed with too much misinformation, dials it back to where it looks right, then switches to auto so the unit enhances his setting from there. Getting the baseline right by hand before letting auto take over is the key. He demonstrates the process in the episode.
Color erase lets you remove colors that are not telling you anything, generally the blues and about half the greens, so bait shows up as just the red marks that matter. You go to menu, more options, color marker, color erase, and uncheck the blues and half the greens. It depends on water clarity, but it stops random blue returns from making you think there is something there. Scott walks through it in the episode.
When he is bait fishing, Scott turns scroll speed up to four, five, or six in the advanced menu so he learns faster what is under him. Offshore he just leaves it at six all the time. A faster scroll updates the picture more quickly so you react sooner. He explains his scroll-speed approach in the episode.
We get a ton of questions about transducer settings and the high chirp versus low chirp debate, and how to mark fish both inshore in shallow water and offshore when you are swordfishing. Scott Walker has his Into the Blue rigged with everything Simrad makes, including chirp sonar, and he has the settings dialed for every depth. When anglers want a straight answer on when to use what, he is the one I trust. Hear him explain it in the episode, so press play in the player above.
Chirp is a more intense signal that separates the fish from the bait, so instead of meatballs you see predators and bait distinctly. Scott's rule is clean: inside 600 feet use high chirp, outside 600 feet switch to low. Inshore for snapper he sets the source to high; heading offshore for tuna and swordfish he switches the source to low right at 600 feet, and the unit handles the rest except gain. He covers the source switch in the episode, so press play in the player above.
Scott does not just trust auto gain out of the gate. He turns auto off, runs the gain up until the screen starts to bleed with too much information, backs it down to where it looks right, then flips to auto so the unit enhances his baseline. That manual step is what keeps the picture honest. He demonstrates how he finds that sweet spot in the episode, so press play in the player above.
Pilchards sit so tight on the bottom that they mark right along with it, which makes them hard to see. Scott sets up a split screen with echo, the chirp view, and downscan side by side so he can tune down until he is almost not marking anything and still confirm he is seeing pilchards. Downscan's ghostly white marks confirm what chirp suggests. He builds the split screen step by step in the episode, so press play in the player above.
A cluttered screen full of blues and greens makes you chase fish that are not there. Scott goes to more options, color marker, color erase, and unchecks the blues and about half the greens so bait shows as just red marks. How aggressive he gets depends on water clarity. It is a small adjustment that makes the whole picture readable. He walks through it in the episode, so press play in the player above.
The chirp versus downscan question is not either-or, it is knowing which tool the depth and the target call for. The 600-foot rule, a hand-set gain, and a clean screen are what turn a confusing display into a fish-finding machine.
Set your source by depth, dial your gain by hand before trusting auto, and erase the colors that lie to you. Press play in the player above for Scott's full walkthrough.
Captain Scott Walker · Into the Blue · Simrad · chirp sonar · high chirp · low chirp · downscan · color erase · pilchards · swordfishing · Waypoint TV · How 2 Tuesday · Tom Rowland Podcast
How 2 Tuesday is my weekly series where I break down one fishing skill at a time, from knots and casting to gear, tactics, and the habits that make you a better angler. Watch and listen to every How 2 Tuesday episode from Tom Rowland.
Captain Scott Walker runs Into the Blue and is one of the most respected charter captains in the Florida Keys. He rigs his boat with a full suite of Simrad electronics, including chirp sonar and downscan, and is known for translating complex sonar settings into simple, on-the-water steps. He is a frequent How 2 Tuesday guest in the Simrad electronics series.
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