CHIRP versus Conventional Sonar

What you need to know when shopping for sonar

CHIRP or conventional sonar
Conventional sonar (left) sends and received a single frequency, while CHIRP sonar (right) sends out and receives a wide range of frequencies, which allow for better definition of targets and less interference.Courtesy Navico

Any boating angler who’s shopping for a new fish finder today will face this question: Should I buy a CHIRP sonar or stick with conventional technology such as a 50/200 kHz sonar?

The simple answer is: Choose CHIRP.

yellowfin tuna caught
The result of upgrading to CHIRP is the ability to find and catch more fish, including pelagic species such as yellowfin tuna, a fish that can be difficult to see on a conventional sonar.JIm Hendricks

I could go into a lengthy explanation about why CHIRP technology better than conventional sonar.

Instead, I’ll will tell you about my own experience and why I am so glad I upgraded to CHIRP.

CHIRP screen shot
CHIRP transducers, when coupled with a compatible CHIRP-enabled sonar, offer greater resolution than with conventional sonar.File Photo

I recently installed a new multi-function display, one that lets you choose sonar technology based the transducer installed on the boat. Initially, I stuck with the existing 50/200 kHz transducer and selected the appropriate setting in the men.

After one trip offshore, I was disappointed. My new sonar failed to show any tuna on the display, even though I saw them under the boat as we chummed them into a feeding frenzy. OK, with fishing like this, who needs a fish finder, right? But still, there are days when tuna are hard to find, and that’s where a good sonar helps.

Sonar screen showing fish
CHIRP sonar also reduces clutter, so that images of bait schools and fish show up more clearly on the fish finder display.File Photo

I talked over the issue with a number of experts from marine electronic companies, and many pointed out that tuna (despite what you might see on TV shows such as where captains are often “mawkin” fish) can be difficult to detect with conventional sonar.

Tuna have relatively small swim bladders, so sonar signals don’t bounce well off of this species. Tuna also move fast, so they don’t stay within the cone of the transducer beam for long, which makes the marks they produce small on the screen.

Regulator 32 on water
Low-profile CHIRP transducers such as the Airmar B175HW are ideally suited for today’s fast center console boats.Courtesy Regulator

The solution was upgrading to CHIRP, technology that produces a wide range of frequencies from low to high in a single pulse (versus a single frequency from a conventional sonar), plus the advanced processing power of my new MFD, which would give me that best chance to mark tuna.

So I got a CHIRP transducer, after talking with Airmar Technology Corporation’s Jennifer Piper, who posed a number of questions about my fishing style before recommending one. Therein lies the rub: CHIRP technology has resulted in more transducer choices than ever before. The choices can be boggling. Before you pony up for a CHIRP transducer and install it, talk things over with a marine electronics expert to make sure you get the best one for your style of fishing.

B175HW CHIRP transducer
The versatile, low-profile B175HW CHIRP transducer from Airmar Technology Corp. broadcasts sonar signals over a range of 150 to 250 kHz at a 25-degree beam, which is superb for finding pelagic fish, as well as structure-oriented species such as grouper and snapper.Courtesy Airmar

I chose an Airmar B175HW, which broadcasts sonar signals from 150 to 250 kHz with a 25-degree beam angle, much wider than the 12-degree beam of my old transducer (on 200 kHz mode). Now I can see tuna well. The same CHIRP transducer is also great for fishing structure spots at depths to 300 feet.

There are downsides to top-end CHIRP transducers. For one they are big. Mine required a 3 7/8-inch diameter hole in the hull. They are also expensive. Retail for the B175HW is around $1,300. But if you’re serious about seeing fish, a top-of-the-line CHIRP transducer is well worth the investment.