Boat fishing: From depth sounder to fishing rig

​For boaters, the first simple depth sounders were primarily a safety measure: How deep is it? Is the seabed rising? Is there still enough water beneath me? For anglers, a second question soon arose: Are there any fish there?

​The classic 2D fishfinder translated the underwater world into arcs, lines and colours. Anyone who could interpret it gained valuable information about water depth, seabed hardness and features. Yet it remained an interpretation. The device did not display a real-life image like a camera. It displayed acoustic echoes that people had to learn to understand.

Then the images became clearer. CHIRP provided better target separation. Down-Imaging produced almost pictorial images of structures beneath the boat. SideScan made it possible to scan large areas of water to the left and right of the boat. Digital nautical charts became more accurate, and displays larger, brighter and faster.

Changes in the fishing scene

And then came the breakthrough that truly transformed the fishing scene: live sonar. Modern live sonar systems display movements in real time. Fish, bait, structure and presentation appear on the screen as they happen. It’s fascinating, sometimes almost surreal, and has now become an integral part of the set-up for many discerning anglers.

Nevertheless, a good system doesn’t start with the top-of-the-range equipment. It starts with a clean, basic set-up: a display on the console, a transducer at the stern. Anyone wishing to equip a fishing boat sensibly usually starts with a chartplotter on the console and a modern transducer on the transom. This set-up is the foundation. It helps us as we travel, search and navigate. It shows what lies beneath and alongside the boat whilst we’re on the move.

In practice, many people refer to a ‘3-in-1’ transducer at the stern. This usually refers to a transducer that provides three key views: classic 2D CHIRP, high-resolution down-imaging and side-imaging. 2D CHIRP is the classic fishfinder view. It shows the water column beneath the boat. Depth, the seabed and structures are visible in a real-time display.

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Down-Imaging – also known as DownScan, Down Imaging or ClearVü, depending on the manufacturer – produces a much clearer image. Side-Imaging is like a large searchlight sweeping to the left and right. The transducer scans to the sides of the boat and uses this data to build up an image of the riverbed. You no longer need to pass directly over every feature. You can run the transducer parallel to a structure and see what’s happening to the left and right. SideScan is often the preferred mode, particularly when fishing for predatory fish.

More than just a screen

The display on the console is no longer just a monitor for sonar images. Modern devices serve as chartplotters, control centres, data hubs and workstations all in one. They display sonar images, manage waypoints, record tracks, display digital nautical charts and, depending on the system, integrate additional components: bow thrusters, engine information, transducers and battery data. For a fishing boat, the digital nautical chart is almost as important as the sonar image.

If you use a good chart, you’ll navigate more safely and fish with greater precision. Detailed depth contours show ledges, plateaus, channels and shoals. It gets even more exciting when the chartplotter can create its own charts. You can then systematically cover an area whilst the device collects depth data. This results in your own, often astonishingly precise chart. If you spend a lot of time on smaller, less well-mapped lakes, this helps you build up a real understanding of the waters.

Screen size also plays a role. A seven-inch device can be a sensible choice for compact boats. However, anyone wishing to use the chart and fishfinder simultaneously will quickly realise that there’s no substitute for screen space. Nine inches is often the starting point for serious work. Twelve inches is the best compromise for many fishing boats: large enough for clear depth sounder images and split-screen display, yet still easy to integrate into the console or cockpit.

The split-screen feature is particularly useful in practice. On the left, the digital chart; on the right, SideScan. Or the chart and 2D CHIRP. Or Down Imaging and Side Imaging simultaneously. As the boat moves, the skipper can see the route, identify the depth, mark features and decide immediately whether to investigate an area in more detail. This is how the electronics become a tool.

The next step: Live Sonar

So far, we’ve been talking about a very high-performance, traditional set-up. A display on the console, a transom transducer, a digital chart, and a reliable power supply. For many anglers, this is already a complete system. But developments in recent years have taken things further: suddenly, you’re no longer just seeing that there are fish there. You can see live how they’re behaving. Live sonar is the area that has sparked both the greatest fascination and the most debate. A traditional transom transducer mainly shows what has passed beneath or alongside the boat. Live sonar shows what’s happening right now. In real time.

In front of the boat, beneath the boat or, from a broader perspective, depending on the rig and technique. This changes how it’s used. You’re not just looking for structure. You observe behaviour. A fish is positioned at an edge. The lure sinks towards it. The fish rises to meet it, turns away, follows, strikes or ignores it. Anyone who has consciously observed this once will understand why this technique is so effective.

For a live system, a second screen is usually a good idea. The first screen on the console is reserved for the chart and the stern transducer. At the bow, there is a second display showing the live feed. That’s where you fish, that’s where you cast, and that’s where you work the bait. Larger set-ups include a third screen as well.

The key factor is how the live sensor is fitted. A common solution is to mount it on the bow thruster. The sensor then faces in the same direction as the bow thruster. Anyone steering actively using the foot pedal will have a clear view ahead.

However, this solution has its limitations: when the bow thruster is used as an anchor, it rotates automatically to maintain the boat’s position. This is great for keeping the boat in position, but it makes it difficult to get a live image.

That is why many anglers use a separate transducer rod. It is mounted on the bow or on the side of the boat and turned by hand. The bow motor can hold a spot-lock position whilst the angler independently adjusts the live fish finder. Even more convenient are electrically controlled fish finder rods, which are operated via a foot pedal, remote control or chartplotter.

Live Sonar is therefore not just another image. It fundamentally changes the way you fish: you read the water, the chart and the structure, but you also see the fish’s reactions. This can help you fish more efficiently. It can also be a humbling experience, because you suddenly realise just how often fish see the bait but don’t take it.

360 degrees: The panoramic view

Alongside live sonar, another technology has become established: 360-degree imaging. Whilst live sonar displays a specific area in real time, 360-degree imaging works more like a rotating side-scan. The transducer scans the area around the boat and uses this data to build up a panoramic image. The boat is at the centre, with the surrounding features arranged in a circle around it.

360-degree imaging is not a substitute for Live Sonar, but rather offers a different perspective. Whilst Live Sonar shows movement and reaction, 360-degree imaging focuses on space and structure. Together, the two systems can provide a very comprehensive picture.

Market Overview

In the fishing boat market, three manufacturers in particular play a major role: Lowrance, Humminbird and Garmin. All three have their own strengths, their own operating systems and their own ecosystems. Newcomers should look not just at a single device, but at the whole system: display, transducer, charts, network, bow motor connection, live sonar, 360-degree options and operation.

Lowrance has a strong presence in the fishing boat market. At the top end is the HDS Pro series, whilst the Elite FS series is worth considering in the mid-range. For the classic transom transducer, there’s Active Imaging HD with CHIRP, DownScan and SideScan. Live sonar is known as ActiveTarget 2. With ActiveTarget 2 XL, Lowrance has expanded the live view. When combined with two systems, the HDS Pro can even display a live 360-degree image.

Humminbird’s system is based on the integration of the display, bow motor and network. The current chartplotter ranges are XPLORE and APEX. XPLORE offers modern controls, powerful charting and imaging functions, as well as AutoChart Live. APEX is the high-end solution featuring large, high-resolution displays. MEGA Live 2 is available as a live system. MEGA 360 Imaging is the best-known solution for a 360-degree view. In addition, there is TargetLock, an electrically controlled solution that allows a live transducer to be aligned independently of the bow motor.

Garmin has a broad range of products with ECHOMAP and GPSMAP. ECHOMAP is an attractive entry-level option for many fishing boats, whilst GPSMAP represents the more connected range. At the top end of the range, the GPSMAP 9000 series demonstrates the direction in which display technology is heading: higher 4K resolution, greater processing power and enhanced connectivity. When it comes to live sonar, Garmin is strongly represented by LiveScope. LiveScope Plus with the LVS34 and LiveScope XR with the LVS62 are well-known systems offering different ranges and applications. The Garmin Spy Pole, when used in conjunction with the GT360UHD transducer, is also an exciting option, as it combines live imaging, a 360-degree view and motorised transducer guidance in a single system.

The dream rig of today

What is possible today would have looked like a trade fair model from the future just a few years ago. Some fishing boats now feature four displays: two on the console, two at the bow. A modern 3-in-1 transducer is in operation at the stern. At the bow, a live transducer points forwards. A second live transducer provides a different perspective. Added to this is a 360-degree system. The bow motor holds the boat in place using a GPS anchor, follows routes, scans the edges or hovers over a spot at the touch of a button. Out on the water, this makes for a much calmer experience: the boat hovers along a edge. No drama. No frantic manoeuvring. The angler stands at the bow, looks at the displays, turns the transducer rod, casts the line, watches the bait, adjusts the angle, lets it sink, accelerates, stops. Meanwhile, a whole technical infrastructure is at work in the background.

Four displays will only make a real impression if the cabling, power supply, installation and operation are all up to scratch. That is why professional installation is so important. Modern electronics require clean power. Multiple displays, live modules, 360-degree systems, bow thrusters and accessories draw a lot of power. LiFePO4 batteries are the ideal solution for many set-ups because they offer high usable capacity, low weight and stable voltage. However, they too must be correctly sized, protected, charged and installed.

These days, a fishing boat is a complete system. If you simply bolt on equipment, you’re wasting potential. If you plan carefully, you’ll gain clarity, safety and enjoyment.

Technique, responsibility and the essence of fishing

Of course, it’s perfectly fine to remain critical of all this. Modern fish-finder technology is changing the way we fish. Live sonar and 360-degree systems reveal much that used to remain hidden. They boost efficiency. They can increase the pressure on fish. They are reshaping the skills required. Whereas anglers used to have to read the water above all else, today they also have to read screens.

This is an opportunity, but also a responsibility. The crucial question is not whether technology is good or bad. The question is how we use it. Those who make conscious use of modern systems can gain a better understanding of our waters, navigate more safely, fish more effectively and locate, catch or release fish in a more sustainable way.

Anyone who simply lets themselves be carried along by the screen may lose a little of what makes fishing so special: observation, patience, intuition and a connection with nature.

If you just stare at the screen, you lose your feel for the water. If you use it properly, you gain depth.

Ultimately, the two must go hand in hand. The boat, the water, the wind, the birds, the edge of the bank, that first cast at dawn. And alongside that, modern technology, which helps us to understand more deeply what is happening beneath the surface.

The developments of recent years have been impressive. A simple fish finder has evolved into a connected fishing system. Depth contours have become precise maps. Echoes have become images. Guesses have given way to real-time observation.

But the best moment is always the same: being out on the water, positioning the boat just right, presenting the bait neatly, reading the fish and, finally, feeling the bite.