Taking the mystery out of sonar

By Gord Ellis

When you work in the outdoor-writing field, focusing on the more complex aspects of angling is easy. New stuff and advanced techniques tend to appeal to seasoned anglers and editors alike. Over the past years, however, I've learned that there's a hunger for the basics of fishing. The nuts and bolts of the sport, whether it be knot tying, hook sharpening, or drag adjustment, are critical things that all anglers need to learn. They also require a bit of practice to get right. Yet, when perfected, these skills greatly enhance the enjoyment of fishing.

Oddly enough, the tool that can help an open-water angler the most is also the one that can be the most frustrating. The modern fish finder or sonar is a must-have item for most anglers. It's also safe to say that just about every fish finder on the market can do most of what it promises. Liquid Crystal Display (LCD) finders are the most common. The problem is that many anglers have no idea how to make them really work for them. They simply press the auto button, sit back, and watch fish-shaped icons scroll by. When used properly, electronics should be your eyes underwater, but you have to know what you're seeing and why you're seeing it. The fish finder should be your best friend, not a mysterious enemy. Here are some of my basic fish finder dos and don'ts.

Dos

1) In most angling situations, shut off your finder's fish ID. This sounds like heresy, but those little fish icons can be misleading. When fish ID mode is on, the LCD displays any object in the beam as fish. So weeds, air bubbles, logs, and even the thermocline can show up as a long string of fish. Yes, the little computer on most fish finders will also mark actual fish as a fish icon, but figuring out which is which can be confusing. Fish finders can't truly tell you for sure whether something under the boat is a school of baitfish, a loon, or a giant walleye. Yet, with practice, you can learn to identify fish, bait, weeds, and other underwater objects by interpreting the raw signal. You might have to adjust the gain setting to remove some of the clutter on the screen when you disable the fish ID. Most finders allow you to turn off the fish ID by going to the menu.

2) Use your zoom setting. Over the last few years, I've asked anglers attending my walleye seminars whether they use the zoom setting on their fish finders. Surprisingly few know what zoom is or that they have it as an option. Zoom is great when you're walleye or lake trout fishing in particular, as it gives you a close-up picture of what's happening on the bottom. There's really no use looking at all 60 feet of a water column when most walleye will be within a foot of bottom. By using your zoom setting (usually 2x or 4x) you can get a more defined look at the bottom. You'll also have an easier time recognizing fish. Walleye usually mark like L shapes leaning on the bottom in the direction of the boat. Some fish might show as suspended blobs. The perfect arc of a fish off bottom is relatively rare when using an LCD fish finder.

3) Buy the unit with the most vertical pixels you can afford. The more pixels, the better the screen resolution. The top of each column on the fish finder's screen represents the position of the transducer, and each pixel in the column represents an amount of distance from it. If you have 200 vertical pixels in each column of your finder, and you're set to read 200 feet of water, each pixel would represent 1 foot of depth. Sonar echoes coming from a fish that's down 60 feet will cause the unit to darken the 60th pixel. When the finder reads an especially strong echo, it will darken the 61st and 62nd pixels as well. Stronger echoes are recorded as marks that are thicker from top to bottom.

4)Read the fish finder's manual. I know, it's not done, but all the information you need to run it well is there. If you don't have a manual, go on-line and visit the fish finder company's Web site. Usually the information you need is posted.

Don'ts

1) Don't leave your fish finder in permanent auto mode. Standard factory settings are good when you're running at high speeds, and they allow you to get important information like depth readings with no adjustment or knowledge of the machine, but auto mode has limitations. In some situations, shallow-water fishing in particular, auto settings and digital depth displays can have trouble giving a proper reading. In this situation you must go to the menu, shut off auto mode, and set the reading for the shallowest depth possible. Auto mode also usually runs fish ID.

2) Don't leave your fish alarm on. Anyone who's spent a day fishing beside a boat with the fish alarm going off every 5 seconds will thank you for disabling the function. If you want to know when a fish is under the boat, check the screen!

3) Don't buy a unit loaded with gimmicks. The simpler the fish finder, the easier it is to learn and understand. If the manufacturer claims the unit will identify a certain species of fish, has multiple sonar-beam modes, or has more buttons to press than a shuttlecraft cockpit, you might want to look elsewhere. Look for a finder that has large, simple keypads, a screen with at least 200 vertical pixels, and a good warranty. Once you get a grasp of the basics, you can decide whether you want to purchase a unit with more complicated options.

4) Don't expect all the fish you see to bite. Fish finders are amazing tools, but they won't make a fish take a lure. Many people (my dear wife included) think marking a few fish pretty much guarantees catching them. Not so. Like downriggers, temperature probes, and more recently video cameras, fish finders simply let you understand better where the fish are and why they are there.

These are just a few simple guidelines to LD fish finder operation. For some people, fish ID and auto mode might be the way to go. Ultimately, it's up to you as the user to decide what settings work for you. A fish finder is a great angling tool and should be your best friend on the water. This fall, get out with your unit and get to know each other.