Vertical jigging is one the most common and productive ways to present baits and lures to bottom-oriented fish. A strictly vertical presentation, one in which the lure is able to remain near or within the traditional 2D sonar beam, allows anglers to monitor their lure, and the fish reacting to it, in real time.

Humminbird's new low-Q, true-CHIRP transducers provide anglers with exceptional 2D sonar performance, especially with respect to clarity, detail, and target separation. These transducers provide users with three different 2D sonar frequency ranges to transmit and display:

The Narrow CHIRP spectrum is designed for high-resolution work. Its compact cone angle provides coverage of the bottom and the water column equivalent to 0.47 x water depth, which is more coverage than is provided by the old benchmark 200 kHz frequency's 20 degree cone angle (0.33 x water depth). Notice also that Narrow transmits a frequency spectrum at the higher end of the 2D sonar frequency range. Resolution, or target separation, increases as sonar frequency increases, so it is to be expected that the Narrow CHIRP frequency range should provide the best 2D sonar resolution.

The Wide CHIRP spectrum is designed for greater coverage of the water column and the bottom. Its more expansive cone angle provides coverage of the bottom and the water column equivalent to 0.90 x water depth, which is a little less coverage than is provided by the old benchmark 83 kHz frequency's 60 degree cone angle (~ 1.0 x water depth). Notice also that Wide transmits a frequency spectrum at the lower end of the 2D sonar frequency range. Because resolution, or target separation, increases as sonar frequency increases, it can be expected that the Wide CHIRP frequency range should provide lower resolution 2D sonar views.

The Full CHIRP spectrum is the only user-adjustable frequency spectrum. The default Full CHIRP range is 150-220 kHz, but users can open this up to 140-240 kHz. The Full spectrum option is designed to provide users with the "best of both worlds", coupling the broad coverage of Wide with higher resolution returns from Narrow.

In this article, we explore the utility of each of the three 2D CHIRP sonar settings for vertical jigging. For this initial study, we elected to focus on water that is less than 15 feet deep (which we would consider to be shallow water), and to use a dainty sonar target, something that might be on the small side for most vertical jigging applications: a 1/16 oz VMC Mooneye jig dressed with a 1.5" soft plastic. This was presented on a St. Croix Panfish Series rod (PFS70LXF) rigged with a 1000-series Shimano spinning reel, which was spooled with Seaguar Smackdown braid (20 lb test, 6 lb diameter) in the Stealth Grey color. The selection of a relatively compact sonar target is based on this simple reasoning: if we can see something small, it should be easy to see a more "traditonal" size target, like a heavier jig adorned with a minnow, or a drop shot rig dressed with a larger soft plastic.

In performing these tests, the only setting we changed was the 2D CHIRP frequency range (Narrow/Wide/Full); all of the other common 2D sonar settings (sensitivity, contrast, 2D SwitchFire, Surface Clutter, Chart Speed) were held constant, so the images below reflect only the impact of the frequency selection.

Hardware for the test images was a SOLIX SI G2 unit with our standard three transducer configuration - a left SI transducer, a right SI transducer, and a dedicated 2D skimmer - all interfaced to the SOLIX unit with SIDB and SILR splitter cables. All of the hardware is off-the-shelf with no special modifications. We are also running the latest SOLIX software, which currently is 3.400. With that said, bring on the results!

How does the Full CHIRP 2D spectrum perform when there are other targets in view, like fish? Well, I admit that it performed much better than did the angler. No trouble seeing the fish ( I would count 4 well-resolved fish targets) as they respond to the lure - the only problem was that they could not be induced to bite. Just because you can see them, doesn't necessarily mean that you can always catch them!

So, the next time you're vertical jigging in relatively shallow water, and want to track your lure and the fish relating to it, give the Full CHIRP 2D spectrum a try. I think you'll be impressed with the results!