Back in the day, grandpa and dad used an old hand-cranked auger when drilling lots of holes in the hard water to catch dinner. Nowadays, I’m thrilled that we use Sonar imaging systems to locate fish, and that when we drill holes, the augers are gas-powered. Let’s look at the Down Imaging system, popular today and see why it may not be the best for ice fishing today.
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What is Sonar?
Sonar is like radar, but it uses sound waves instead of radio waves. Similar to the echolocation used by animals like dolphins and whales to locate objects at great distances, it’s more or less a natural form of sonar.
In much the same way dolphins have used echolocation to find food, anglers have been using sonar to find fish for years.
Sonar works via a transducer, which is an electronic device that converts electrical energy to another form. Radar changes electricity to radio waves. Lidar converts electricity to light waves, and sonar converts electricity to sound waves.
A sonar transducer emits sound waves in brief, recurring bursts. The time sound waves take to return is used to calculate an object’s distance and location. Sonar sound waves detect changes in density, with fish. It’s the lower density of their air bladders that register on a fish finder’s sonar.
Fishfinders are high-frequency devices ranging on average from 50-200KHZ, which translate to 50-200,000 cycles per second. Lower frequencies penetrate deeper water and have a wider search area, but may display blurry images. Higher frequencies give better images. Resolution in a narrower triangular search area and functions best in shallower water.
Does Sonar Work Through Ice?
Let me answer that question with a question, does an Ultrasound Work through an expectant mother’s skin? The answer is a big yes to both questions.
Sonar is an electromagnetic wave. Even at lower frequencies, such as a 50 KHZ setting, you’re talking about 50,000 cycles per second, more than enough to pass through solid objects. Sonar passes through many solid objects better than it passes through air or water.
Getting the most out of a day of ice fishing is about a good time and resource management, not to mention, bringing home dinner. By side-stepping the need to drill multiple holes, Sonar helps save both time and your back. A big perk is not letting the fish know you’re coming when drilling holes.
Shooting Sonar Through the Ice
When shooting through the ice, remember sonar 101 tells us the sonar signal bounces back of changes in density, which can mean many types of rubble or even air bubbles in the ice. The point is clear, fresh ice works better.
When clear ice isn’t available, scrape snow off the ice until you have a smooth surface. Pour water on the ice and place your transducer in the water, contacting the ice surface. The water helps transmit the signal through the ice. If your image isn’t clear, add more water and turn up the sensitivity (gain).
Later in the season, when ice is thicker or clouded from the freeze-thaw cycle, you can still use sonar through the ice. Look for previously drilled holes that have frozen over, the new ice should be clearer. Thick Ice isn’t necessarily a deal-breaker. Sonar can pass through thick solid objects.
The good news is there is no need for new or special equipment. You do all this with the fish or depth finder you already own. If you don’t have one, no need to break the bank. A middle-of-the-road model should get the job done. Look for a CHIRP (concentrated high-intensity radar pulse) type fish-finder and be sure a transducer is included.
Does down imaging work for ice fishing?
Down imaging is a combination of traditional 2-D sonar and down sonar generating near-photo quality images. As a result, realistic displays of underwater environments, objects, and fish are produced.
The frequencies used in down imaging range from 455 KHZ to 800 KHZ. As with traditional 2-D sonar, these high frequencies operate best in shallow waters. Also, depth and image quality are directly proportional to frequency. The higher end frequencies don’t probe as deep, but yield sharper images, while lower frequency signals reach greater depths and cover a wider image area.
Down imaging works best on boats in open water that are moving at least 2-4 mph. So, using it with a stationary transducer on the surface of the ice Doesn’t return the high-quality images, typically associated with down imaging.
Using down imaging through the ice can produce some minimally usable results, but they won’t be any better than a conventional 2-D sonar would produce. So, if you have a unit that does down imaging, use it. Still don’t have a down imaging system, don’t go out and buy one just for ice fishing.
Live Scope Scanning: An Alternative to Down or Side Imaging for Ice Fishing
At the forefront of fish imaging/location technology is the Panoptix-Livescope system from Garmin. The combination of sonar scanning and Panoptix image combine to generate startling, real-time images of what’s beneath your boat with a multi-directional range up to 200 feet.
Designed for open water, the Panoptix-live system adapts well to ice fishing. Sure, you’ll still drill a hole, but through that single hole, you’ll get real-time images of fish in any direction up to 200 feet away, allowing the coverage of sizable areas quickly.
When you see fish, mark their distance and direction, walk to that spot, drill a hole and begin fishing.
Whether these live scanning systems are worth their cost for recreational fishing is up to you. However, if fishing in tournaments, guiding others, or commercial fishing is how you make your living, then they’re a must-have. Their use underscored the value of these systems on the North American Ice Fishing Circuit.
Garmin brought the technology to market, but other reputable manufacturers are out there. Be sure to do your homework before choosing a system.
Down Imaging vs. Side Imaging for Ice Fishing
By now, I’m guessing you know that down imaging and side imaging are a type of sonar, with their primary difference being signal direction. Let’s look at their similarities, differences, and whether they are compatible.
Signal Types
Down imaging is a blend of customary 2-D side-sonar and a narrow, vertically focused beam. When read they produce near-photo-like images.
On the other hand, side imaging uses multiple, ultra-thin sonar signals moving to the side of the boat. Similar to an MRI, reflected signals are compiled into an image similar to an MRI picture slice.
Images
Down imaging generates a photo-like display that clearly represents underwater environments and fish. Fish species are identifiable with down imaging.
Side imaging displays are the shadows of objects. It can be the lake’s bottom, your target species, moving or swimming, or even obstructions in the water. Images displayed are better than conventional 2-D sonar, but with less clarity than down imaging.
Boat Speeds With Down Imaging & Side Imaging
Traditional sonar works best with movement. The same is true of both Down imaging and side imaging. For both down imaging and side imaging, speeds of up to 8-10 mph work best to maintain image quality.
Both down imaging and side imaging lose image quality when sitting still or anchored. To maintain image quality, a minimum speed of 2-4 mph is recommended. If you come to a full stop, switch to standard sonar.
This means that both systems lose image quality when ice fishing because of stationary use.
Water depth and range
Down imaging is best for deeper water because of its vertical scanning beam that maxes out at 300 ft. Anything deeper and you’ll want to use a 50 KHZ CHIRP type system to read deeper waters.
Side scanning, of course, works best in shallower waters. Because its signal goes to the sides of the boat, it gives you a more complete picture of what’s below you.
Which is Best?
Neither system stands head and shoulders above the other. What it comes down to is where you usually fish. If you’re usually in shallower waters, then side scanning is better. But if you fish deeper waters most of the time, then down scanning is the obvious choice.
It seems the best solution is to strike a compromise and buy a unit that does it all: standard sonar, down scanning, and side scanning. The Lowrance Hook Reveal 7 is a good place to begin looking.
| Down Imaging vs Side Imaging for Ice Fishing | ||
| Down Imaging | Side imaging | |
| Signal Type | Narrow side and vertical sonar beams. | Multiple ultra-thin side sonar beams. |
| Image type |
|
|
| Motion or boat speed | Minimum 2 mph. Image resolution lowers when used stationary. | Minimum 2 mph. Image resolution lowers when used stationary. |
| Shoot through the ice | Yes, but image quality will be lowered. | No, must be used through a hole in the ice. |
| Best depth | Best in deeper waters. | Best in shallow waters. |
| Range | 300 feet. | About 200 feet to the sides of the boat. |
What’s it all Mean?
Both down imaging and side imaging systems require minimal movement to yield the highest quality images. For that reason, I can’t recommend running out and buying a down imaging system solely for ice fishing.
A pricey, high end alternative to Down imaging is the different live scanning systems on the market today. They provide innovative imagery to locate your target species in open water or under the ice. Whether they warrant their cost is a personal choice.
If you already have a down imaging system, use it. It will help you avoid drilling holes and find the fish. Otherwise, use the traditional sonar depth finder you already have to know where to drill only one hole to start fishing.