InTheBite

  • Home
  • News
    • All News
    • Featured Stories
    • General News
    • Captain of the Year
    • Tournament Results
    • First Builds
    • Splash Reports
    • Old Salts Rule
    • Tackle Tips
    • Dock Talk
    • Crew Records
    • Conservation
  • Tournaments
    • Calendar
    • Captain of the Year
    • Champion’s Cup
  • Shop
    • All Products
    • Subscriptions
    • Back Issues
    • Shirts
    • Hats & Visors
    • Miscellaneous
    • Release Rulers
  • Classifieds
  • Job Board
  • Contact
    • Contact InTheBite
    • InTheBite Media Kit
  • Log in

Periscopes: Where Marlin Fishing Meets the Hunt for Red October

October 28, 2019 By InTheBite Editor

By Steve Katz

When it comes to finding the best fishing grounds, some captains seem to have that fifth sense. Such helmsmen can consistently navigate to productive waters using little more than visual observation of the conditions and a chart or two. On the opposite end of the spectrum, some captains won’t leave the dock without the latest in high-tech gadgetry– satellite images, altimetry data and multiple on-board fish finding sonars and the like. For most captains, it is a happy medium that combines local knowledge with the right amount of technology that guides their search for productive water.

Finding productive-looking water is just the first step in the equation. Once there, how do you know that the fish are there? Most of us use a finely tuned echo sounder/fishfinder/ sonar. Others deploy the spread to see what awaits. What if there was something even better, a way to “see” if there are any fish around your boat in real time?

Sonar mounted in the center of the hull with fairing in the opening.

How a Fish Finder Works

At its most basic level, a fishfinder has a transducer that sends out sound waves in the shape of an inverted (upside down) cone. The transducer then listens for the echo of the waves as they bounce off of an object to determine the target’s distance—whether it be a fish, the bottom, or some other object.  The processor and display then convert these echoed sound waves into a useful image. This picture is a historical view of what was below the bottom of the boat as you move along.

There have been a lot of advances in fishfinders. These include CHIRP, wide angle, forward looking transducers—all that include faster and more detailed data processing capabilities. These improvements  mean that modern fishfinders—from the most basic and inexpensive to the top of the line– all do a great displaying the bottom structure and fish under the boat.

Fishfinder technology in the sportfishing space has recently been revolutionized by technologies that were once reserved for military and commercial fishing applications. Chief among these advancements are multibeam sonar and scanning sonar. Early adopters of this new sportfishing technology benefit from increased clarity and accuracy of imagery. Some products even provide data in near real-time.

“Marked one…get ready.”

Multibeam Sonars

A multibeam sonar has an array of multiple sonar emitters in one fixed transducer. These multiple beams are digital. They are “moved” to scan a wide angle, often 120-degree coverage, using hardware and software. How revolutionary is this 120-degree coverage? A traditional echosounder has a beam as narrow as 4-degrees. 

Examples of multibeam sonar used in sportfishing include Garmin Panoptix, Simrad StructureScan® 3D and Furuno DFF-3D. These systems allow you to see a historical view of what your boat passed over. Their wide view allows you to “see” the water column to the sides of boat, helping you learn if you are in an area where there are fish or structure.

Sonar deployed.

Scanning Sonar

A scanning sonar works like your radar underwater– you can think of it kind of like “The Hunt for Red October.” Scanning sonars include a transducer housing that is lowered into the water from a storage tube within the hull of the boat. This transceiver can be rotated and tilted within the housing.  The transducer can rotate up to 360 degrees creating an image of the water area all around the boat. 

The tilt angle is adjustable for varying water depths and different applications. The Furuno “Searchlight” CH-50 is the most well know scanning sonar options used in the sportfish and commercial fishing markets. While this technology may seem new, the original CH-250 model has been in use for over 10 years—and newer models are currently available.

Technology has enabled the development of newer scanning sonar that does not need to rotate mechanically to capture the 360 degree are under the boat. The newest scanning sonar uses a transducer that deploys downward from the hull, like the Searchlight but consists of multiple stacked elements to transmit the sonar signal in all directions simultaneously. The combination of the processing power of the hardware and the multiple sonar elements allows the system to provide a real-time image of the water below the boat. Yes, that means you can see fishing moving in and out of the sonar beam coverage area!

While there are other manufacturers of scanning sonar, the Furuno Omni (CSH-8L MARK -2) scanning sonar is the most popular with sportfish boats. This unit is fast, able to complete a full circle scan in a half a second, as compared to 32 seconds with the Searchlight sonar. The Furuno Omni sonar uses a retractable transducer that is about 8” in diameter, with 14 layers of transducer elements. These multiple elements are combined electronically in the processor to display a full 360 image. The unit transmits its sonar signal on a fixed frequency of 85 kHz.  The beam angle, how far up or down the transducer “looks” can be adjusted from near zero – which is parallel to the sea surface to 55 degrees pointed downward toward the bottom.

The Omni sonar was originally designed for and used by commercial fishing boats and is a popular unit in Japan. Once the Omni sonar was installed on a sportfish boat and captains saw and caught more fish, word got out and it has become a must have for serious tournament sportfish.  

The most complex part of the Omni sonar is the transducer. You need a suitable area in the machinery space to install the sonar– up to about five feet of clearance inside the hull for a long travel hull unit.  Additionally, the system contains a transceiver, processor and control unit. This is a “black box” system, which can use most any standard marine monitor. As you might expect, a scanning sonar system is more costly than traditional systems, starting at $20,000 for the searchlight CH300 and $75,000 for the Omni CSH-8L Mark 2.  Understandably the complex installation of the system will add to the cost

Sonar hardware below deck.

The Benefits to A Sportfishing Boat

What does a fast scan get you? It allows a real time picture of the fish or lack of fish around the boat.  A traditional echosounder beam “looks” below the bottom of the boat and reports on the screen on the area you just passed over. The Omni scanning sonar can “look” around the boat, in a full 360 degrees with a range out to about 1000’ – a typical range when used for sport fishing. 

The specifications include much longer ranges, though the practical application is dependent on water depth, wave heights and other factors. This Omni sonar allows you to change the tilt angle, something that can’t be done with a traditional echosounder. Increasing the tilt angle allows you to scan more downward and a smaller angle allows you to focus on the top of the water column.

All of these scanning sonars use a stabilization component (motion sensor) to allow the system to calculate and compensate for the boat’s roll, pitch and yaw. Proper stabilization of the image allows the system to draw the sonar picture relative to the ship.

Custom faring for the sonar.

The Learning Curve

There is a learning curve when operating scanning sonar compared to a traditional echosounder.  Interpreting the results on the screen takes some practice. To fine tune your system, you will need to make some adjustments as well.  

Some users supplement the screen image with the audio feature, which emits varying tones when objects are detected in a monitoring zone. Many captains find this audio feature quite helpful.  It allows the sonar to monitor the forward sector of the vessel, while the captain keeps his gaze fixed behind the boat on the spread. He can watch for the rise of a sailfish or marlin, awaiting the squeak indicating the presence of a fish ahead of the boat. 

The track of a hooked blue marlin.

How do you operate and analyze the data from these scanning sonars?

A quick glance at the screen of scanning sonar often shows a red, doughnut-shaped image. What is this really telling you? Before you can interpret the screen, you need to learn more about the settings and adjustments necessary to understand what you are seeing. As the image is real-time, the Omni sonar is more intuitive to operate and interpret. 

Some of the necessary adjustments are similar to a traditional echo sounder– range, gain, TVG and the like. Other adjustments are exclusive to the Omni sonar. These include transmit power, pulse length, TX cycle, noise limiter, color curve, horizontal and vertical beam width and, most importantly, tilt angle. Beyond the adjustments, there are also many automatic functions– such as tilt angle and train sector (rotation) and auto retract (a critical function that retracts the transducer at a predetermined speed– the unit is not designed to operate at speeds over 16 knots).

Conclusion

Technology that was once reserved for science fiction books or for hunting submarines is transforming the sportfishing space. Captains on the Gulf Coast are reported to run up to oil rigs and scan them. If they “see” a marlin they stay and fish, if they don’t—it’s on to the next. Revolutionary technology indeed. 

What Furuno dealers are saying about the CSH8LMK2 Omni Sonar

“It’s a game-changer. The biggest advantage of the CSH8LMK2 is how quickly it paints. You’re not just looking at the water column, but you are actively hunting individual fish. If you’re fishing against one of these boats who have this machine and you don’t, you have a very serious disadvantage. They have one up on you.” Todd Tally. – Atlantic Marine Electronics

Captain Steve Katz is the owner of Steve’s Marine Service Inc in Ocean City, Maryland. He is the Vice Chairman of Board of Directors – National Marine Electronics Association (NMEA) and holds ABYC Master Technician certification, NMEA AMEI, NMEA2000 certificates along with factory training from many manufacturers. To contact Steve, email info@inthebite.com.

Originally published in the June 2018 issue of InTheBite Magazine.

  • Facebook
  • Twitter
  • Email

Do you have any comments or questions for us? We’d love to hear from you.

    Filed Under: Electronics, Equipment Tagged With: fish finders, furuno omni sonar, periscopes

    Recent News

    boats in a marina

    Always Grateful For The People In Our Sportfishing Industry

    By Captain Kevin Deerman I’m very thankful that I have been blessed with the opportunity to work for some incredible owners and their families over the years. They have all been quite different but each of them have given me many experiences, f … [Read More...]

    Builder’s Choice Repeats as Marina Casa de Campo Open Champion

    Builder’s Choice, a 64-foot Jarrett Bay, hasn’t fished the Marina Casa de Campo Open for two years, but the team never missed a beat. The boat led the field of 14 boats from the start to win the 2023 Marina Casa de Campo Open, which concluded last wee … [Read More...]

    Walkaround Sportfishing Boats: Mission and Purpose

    By Ken Kreisler “To be or not to be.” While this well-known Shakespearean quote is not associated with the boating experience, if we filter it through our marine sensibilities, it just might be coaxed into reading this way: Walkaround, express or con … [Read More...]

    2023 Chub Cay Classic Won by Following Seas

    Following Seas, a 58-foot Viking run by Capt. Charlie Vanderbeck, claimed top honors at the 2023 Chub Cay Classic billfish tournament. The third annual event was held March 9-11 at the Chub Cay Resort and Marina. Following Seas released a blue and … [Read More...]

    Weathering the Storm

    While nasty conditions offshore are generally unpleasant for anyone on any vessel, offshore fishing on an outboard-powered center console typically means that the captain and crew will be more exposed to the wind and seas than the crew of a larger … [Read More...]

    Leave a Reply

    Connect With InTheBite

    • Facebook
    • Instagram
    • Twitter
    • YouTube

    Subscribe to InTheBite Magazine Today!

    InTheBite current cover image

    Our latest issue is hitting the docks now! Be sure to subscribe to the hottest bluewater mag on the market. Purchase or Subscribe »

    InTheBite Champion’s Cup

    InTheBite Champions Cup Logo

    New for 2022, the Champion’s Cup is an optional paid entry with a winner-takes-all prize format for teams who want to up the stakes in each division utilizing our longstanding tournament scoring formula.

    Captain of the Year Cup Standings

    COTY / ITB Cup Logo

    News

    • Builder’s Choice Repeats as Marina Casa de Campo Open Champion

      Builder’s Choice Repeats as Marina Casa de Campo Open Champion

      Builder’s Choice, a 64-foot Jarrett Bay, hasn’t fished the Marina Casa de Campo Open for two years, but the team never missed a beat. The boat led the field of 14 boats from the start to win the 2023 Marina Casa de Campo Open, which concluded last weekend in the Dominican Republic. With Capt. Brent Gaskill at the helm, the... [Read More...]

    • 2023 Chub Cay Classic Won by Following Seas

      2023 Chub Cay Classic Won by Following Seas

      Following Seas, a 58-foot Viking run by Capt. Charlie Vanderbeck, claimed top honors at the 2023 Chub Cay Classic billfish tournament. The third annual event was held March 9-11 at the Chub Cay Resort and Marina. Following Seas released a blue and white marlin to earn 700 points to top the field. Under the all-billfish release format, blue marlin scored... [Read More...]

    • Massive Sargassum Weed Line Approaches Florida

      Massive Sargassum Weed Line Approaches Florida

      If you’ve ever headed offshore in search of dolphin under patches or lines of sargassum weed, you know the weed can be difficult to find at times. That seems to happen every time I fish a dolphin tournament at least! But all that may soon change. Sargassum, an algae that’s commonly mislabeled as a “weed,” is headed toward the U.S.... [Read More...]

    • InTheBite Hires Industry Veteran John Brownlee as Editor-in-Chief

      InTheBite Hires Industry Veteran John Brownlee as Editor-in-Chief

      Dale Wills, Founder and President of InTheBite, has announced the hiring of marine industry veteran, John Brownlee, as ITB’s new Editor-in-Chief. “Under Brownlee’s leadership in editorial and digital media, his intelligent perspectives and vast industry knowledge will move the brand forward with his long list of proven skill sets,” Wills said. “It’s only fitting as we move past our 20th... [Read More...]

    • Proposed 10-Knot Restrictions

      Proposed 10-Knot Restrictions

      It’s Not Over! The Viking Yacht Company and the marine industry’s grassroots campaign to stop the advancement of a proposed 10-knot restriction along the Eastern Seaboard continues into 2023. And now, thanks to the National Marine Manufacturers Association (NMMA), we have a tool at our disposal that makes it super easy to make your voice heard. In one click, send a pre-written letter... [Read More...]

    Search InTheBite

    Copyright © 2023 InTheBite, LLC · All Rights Reserved.