PUTTING THE PIECES TOGETHER TO GET THE MOST OUT OF YOUR SONAR!
Sonar technology has evolved rapidly over the past decade. There are now many options available to freshwater anglers, and with those options it becomes increasingly difficult to separate real-world usefulness from marketing hype. 2D/CHIRP. Sidescan. Downscan. Forward-looking (also referred to as “live sonar”). These technologies each offer valuable information about the underwater environment that the other technologies cannot (or at least not as effectively). But are they each worth the investment for species and locations that you fish?
BEST USE OF YOUR TECHNOLOGY
In this article, I assign value ratings for the technologies listed above based on my experience to date in a few different fishing situations. This approach is quite subjective, as not everyone fishes the same way. However, the point is not so much the ratings themselves but rather to highlight that the usefulness of different sonar technologies varies depending on where you are fishing and what you are targeting. I rely on sonar/maps more than most anglers, so hopefully this article will shed some light on technology currently available, and help you prioritize your hard-earned fishing dollar as you plan for open water.
Table Caption: The following table lists the trade names of similar technologies currently available from the big-3 freshwater sonar manufacturers (Lowrance, Garmin and Humminbird). All companies offer multiple 2D/CHIRP transducer types.
SITUATION ONE
Clear water shield lake (Walleye) – Kenora area
Forward looking sonar: 9/10. In my first summer using the LiveSight™ transducer, I was absolutely shocked by how many Walleye I would spot from a distance while trolling that did not eventually (once I tried to troll over them) show up via traditional 2D or downscan. I quickly learned that on clear water shield lakes, Walleye are often spooked and will actively move away from the boat. Without forward looking sonar, it would be easy to assume that a spot was devoid of fish. But even in 25′ of water, they avoid the boat! Needless to say, the information forward looking sonar provides in this type of fishing situation will change how (and where) you fish.
Photo Caption: Before ActiveTarget™ entered my equation, this was my typical screen configuration while trolling for Walleye on the weed flats in a clear water shield lake. You can see how a school of active Walleye (pink highlight) that pass under the boat display quite differently using the TM150M (top left) and downscan (bottom left). Ahead of the boat, the forward looking LiveSight™ transducer (top right) reveals a large bait cloud (blue highlight) ~10 ft in front of the boat, as well as a pronounced weed edge (green highlight) ~45 ft away.
2D/CHIRP: 6/10. As of last fall, I found 2D (specifically the Airmar TM150M at 105 kHz) to be quite valuable when fishing for Walleye in clear water shield lakes as it provides a good “down-looking” perspective. However, based on my brief experience using ActiveTarget™ through the ice this winter, I wonder if 2D/CHIRP will become obsolete (at least for me) when Walleye fishing in clear water shield lakes. In recent Uncut Angling videos, I have noticed that host Aaron Wiebe allocates minimal screen space to his 2D/CHIRP return, instead using his Livescope™ transducers to look forward, but also down at the same time. Such powerful technology!
Downscan: 5/10.
I run downscan fairly often while fishing clear water shield lakes for Walleye. Downscan helps to clarify interpretation (e.g. weeds versus wood), and with resolving individual fish when they are tightly clustered.
Sidescan: 5/10.
For more than a decade, anglers have used sidescan to help understand the subtleties of the habitats Walleye often occupy. Modern sidescan technology from all manufacturers produces much clearer images than versions that were released a decade ago. On a large screen display (9-12”) I find it relatively easy to use modern sidescan to spot suspended Walleye on weed flats (soft bottom). However, picking out bottom-hugging Walleye in a hard-bottom, structure rich environment is near impossible – the contrast between fish (strong sonar return) and hard/irregular bottom (another strong sonar return) simply isn’t sufficient for the fish to stand out. And as most savvy Walleye anglers are aware, these fish are often structure oriented in shield lakes. In my opinion, this reduces the usefulness of sidescan for this fishing situation.
SITUATION TWO
Winnipeg River (Walleye) – Pinawa area, Lac du Bonnet, Pointe du Bois
Downscan: 9/10 and 2D/CHIRP: 6/10.
I’m listing these together because in this fishing situation, they really work hand in hand. When I see a Walleye on the downscan hiding behind a boulder in the Winnipeg River’s moderate to heavy current areas, I get excited. More often than not, a Winnipeg River Walleye that you can see on your sonar is a good sized fish and in the mood to feed. Downscan reveals more Walleye on the Winnipeg River than 2D/CHIRP – even if the transducer in question is an Airmar TM150M operating at 145 kHz (putting out a relatively narrow ~19 degree cone). Simply put, downscan’s narrow slice (the beam is shaped more like a line than a cone) is superior for peering behind boulders, allowing users to identify fish in ambush mode waiting to dart out and smack their unsuspecting prey as it drifts past. However, 2D/CHIRP does occasionally show fish that downscan misses, and when displayed side by side my ability to interpret the underwater world increases.
ONE 2D TRANSDUCER TO RULE THEM ALL?
All manufacturers offer a variety of 2D/CHIRP transducers, but there is good reason to consider something other than a stock OEM transducer if you are after superior 2D/CHIRP performance.
A company called Airmar makes what I consider to be the gold standard for 2D/CHIRP transducers, and they are compatible with Humminbird, Garmin and Lowrance (as well as other sonar manufacturers that cater to the saltwater market). While some of Airmar’s commercial grade 3000w transducers (designed to be used in the ocean where depths can exceed 2000 ft) cost more than some small boats, they also make several 300w and 600w models that are worth considering for freshwater.
The AirmarTM150m CHIRP-ready transom mount transducer is a personal favorite of mine because of its ability to resolve bottom-hugging Walleye at a moderate price-point. As the name suggests, you can CHIRP the TM150m, but you can also specify it to run on any frequency between 95 and 155 kHz. In most situations, I find that 105 kHz (i.e., a single frequency and not a CHIRP’d range) provides the best balance of cone angle (~24° of coverage) and target-separation. However, at times (e.g. Winnipeg River Walleye) I do opt for 145 kHz because this results in a narrower cone angle (~19° of coverage).
Sidescan: 4/10. I don’t find sidescan to be terribly useful in this fishing situation because 1) Winnipeg River Walleye are bottom oriented 99% of the time and 2) all the high-current areas are hard-bottom and highly irregular, making it nearly impossible to pick out a fish’s hard return from the background. I typically use premium maps when I fish the Winnipeg River, but if you do not then sidescan would likely have more value in terms of getting the lay of the land – just don’t expect to see many Walleye, even when they are aggregated.
Photo Caption: If you struggle to interpret sidescan imagery, try overlaying it on your chart/map window. This type of display provides a better spatial perspective.
Forward looking sonar: 2/10. Thus far, LiveSight™ has been pretty much useless to me on the Winnipeg River because the beam is too wide (45°) to differentiate bottom-hugging Walleye from structure. Maybe ActiveTarget™ (18° x 145°) or Livescope™ (20° x 145°) would be effective, but at present I cannot advocate the investment if Winnipeg River Walleye are all that you fish for.
SITUATION THREE
Tannic lake (Crappie) – Whiteshell
Forward looking sonar: 10/10. Being able to follow Crappie schools in real-time is an absolute game changer. Simply put, if you are not in close proximity to significant numbers of Crappie throughout the day, you are destined to do poorly… and on certain days, that means trying to follow the schools as they meander about (with surprising speed!) in open-water. With forward looking sonar, you can position yourself within casting distance of fish roaming mud-bottomed basins much more often than you would otherwise.
Photo Caption: Forward looking sonar’s ability to spot fish a significant distance away is a game changer. This ActiveTarget™ screenshot was snapped while I was ice fishing for Walleye on Lake Winnipeg in March 2021. Three large fish can easily be seen 60 – 70 ft away from where I am jigging. I can’t wait to use this during open-water, casting for fish before they are aware of the boat! Both ActiveTarget™ and Livescope™ provide 145° of horizontal coverage when used in forward mode, meaning that they actually cover the area immediately below you in addition to ahead of where the transducer is pointed.
2D/CHIRP: 7/10 and Downscan: 5/10. As of last fall, both 2D and downscan were useful to me for Whiteshell Crappies because they provided good information below the boat. 2D (TM150M on 105 kHz) more so for jigging Crappies video-game style, but downscan was still periodically useful for determining if I was looking at a couple small versus a single big lock-jawed fish. However, with ActiveTarget™ now being part of my arsenal, I am skeptical that 2D or downscan will get as much screen allocation.
Sidescan: 5/10. It’s crazy how fast things can change with regards to technology. Only 2 years ago, I used to value Sidescan very highly for Whiteshell Crappie. It is fairly easy to see schools of suspended Crappie using modern sidescan because of the hard signal (fish) versus soft signal (substrate) in combination with the acoustic shadows visible when the fish suspend off bottom, although once again screen size makes a big difference (9 – 12” screens preferred). Mark a waypoint on top of the school, and then troll to or cast at the waypoint. Repeat a few minutes later when the fish move. That is what I used to do, and it is still an effective approach. However, forward looking sonar allows me to be so much more efficient that I don’t foresee using sidescan to try to stay on top of Crappie schools anymore.
IN SUMMARY
All of the major sonar technologies are amazing in their own right, and each will make you a better angler. However, as you can see from just three examples, the relative value varies by fishing situation. Cost is always a factor so each angler will have to think about how they fish (or would like to fish going forward), and prioritize what sonar technology will be most useful for them.