Selecting the Right Transducer Frequency for Deepwater Fishing

Immediately, saltwater ­anglers ply ever-increasing depths to catch fish. California rockfish anglers work construction mendacity 600 ft under the floor. Alaska fishermen ­goal halibut in 750 ft. Deep-drop fanatics search tilefish at depths of 1,500 ft or extra. Daytime swordfish anglers drop baits to 2,500 ft or deeper. Whether or not fishing the equal of two soccer fields or a half-mile under the ocean floor, every of those fisheries requires extremely specialised sort out and sonar transducers with frequencies to penetrate the abyss. But there is no such thing as a one frequency that matches all deepwater fishing eventualities, says Craig Cushman, director of promoting for Airmar Know-how Corp., the main third-party provider of marine transducers for manufacturers resembling Furuno, Garmin, Humminbird, Lowrance, Simrad and Raymarine.

“When an angler asks about transducers for deep water, the primary query I ask is, ‘The place are you making an attempt to catch fish?’” Cushman explains. Whereas there are dozens of potential frequencies, it typically boils all the way down to a choice between a medium or low frequency. 

Frequency Fundamentals

Frequency is essentially the most ­essential consider deep ­water. So it’s important to know the rules of transducer ­frequency. Cushman references the sound of a automotive stereo as an analogy when explaining frequency. “When a automotive is taking part in music with the home windows up, folks outdoors may hear the bass notes, however not the treble,” Cushman factors out. “That’s as a result of bass notes broadcast at decrease frequencies, which may higher penetrate the automotive’s thick glass home windows.” By the identical token, lower-frequency sonar (40 to 60 kHz) can higher penetrate the depths. “Because the automotive home windows are rolled down, you may choose up treble notes that would not penetrate the glass however now carry elevated octaves,” Cushman provides. Equally, a higher-­frequency sonar (130 to 310 kHz) won’t penetrate the depths however can choose up high quality ­particulars in shallower water.

Medium-frequency sonar (80 to 130 kHz) strikes a compromise between high and low frequencies. It may well attain ­pretty deep and supply advantages not out there in decrease frequencies. 

Query of Depth

Definitions of deep water fluctuate. “Whereas one angler views 1,000 ft as deep, one other may outline it as 2,500 ft,” Cushman explains. For the primary angler, a medium frequency is perhaps a more sensible choice. For instance, the medium-frequency, chirp-ready B175M mannequin will learn all the way down to 1,500 ft and in addition present robust efficiency at shallower ocean depths.

Nevertheless, the second angler is perhaps disillusioned within the medium frequency. “The B175M may choose up a backside echo at 2,500 ft, however not a lot else,” Cushman explains. “However, the low-frequency, chirp-ready B175L will produce a robust backside studying and present fish and bait at 2,500 ft.”

Goal Separation

On the subject of particulars, medium frequencies have a tendency to point out greater than low frequencies, Cushman says. “In the event you’re on the lookout for grouper or snapper with their chins within the rocks at 800 to 1,000 ft down, the B175M has the efficiency traits to separate these targets from the construction,” he explains.

That is largely due to a narrower beam angle that helps higher outline particulars. The B175M has a beam angle starting from 16 to 11 levels. The B175L, alternatively, has a wider beam angle starting from 32 to 21 levels, and that doesn’t supply the identical sort of goal separation. 

Nevertheless, a large beam provides distinct ­benefits over a slender beam, offering a wider search sample, and that may show useful when on the lookout for species resembling swordfish that swim properly above the underside. In these instances, goal separation is much less essential than the flexibility to view a large swath of the water column, Cushman factors out. 

Learn Subsequent: Utilizing Multi-Function Transducers to Discover Fish

Extra Energy

Transmitting energy represents the ­second-most essential consideration for deep water.   “All issues being equal, a 1,000-watt transducer will carry out higher than a 600-watt transducer,” Cushman says. “It’s like turning the amount up on the automotive stereo—it can simply increase down deeper.” 

Of important significance right here is that the fish finder and transducer should be appropriate when it comes to energy.

Anglers who’re severe about deepwater fishing gravitate to even more-powerful programs that pump out 2,000 and even 3,000 watts, Cushman observes. But the transducers are massive. 

“You want a bigger, ­wider transducer to push power into the water,” Cushman explains. “So, bodily dimension will increase proportionately to will increase in energy.” 

For a comparability, Airmar’s fashionable low-profile, tilted-­component B175 collection chirp transducers talked about earlier have faces with 14.5 sq. inches of floor ­space and pump out 1,000 watts. However Airmar’s CM599 cavity-­mount chirp transducers have faces with 88.8 sq. inches of floor space that produce 2,000 to three,000 watts of energy.  

Nevertheless, lots of right now’s saltwater fishing boats are restricted in the case of transducer dimension. For instance, the CM599 transducer measures 14.5 inches lengthy and 6.13 inches huge, and requires a cavity constructed into the underside of the hull. Examine that to a 3.75-inch-diameter gap wanted for a spherical B175 collection transducer. 

On a 30-foot center-­console boat, the sheer dimension, fiberglass work and expense of a CM599 transducer won’t be sensible and even possible. But nearly any saltwater fishing boat constructed right now can accommodate one and even two of the Airmar B175 collection transducers. 

In the end, the depth vary, goal species, fish-finder capabilities, boat dimension and price range will assist information choosing the correct transducer ­frequency for you, your boat, your fish finder and your type of deepwater fishing.