Article by Capt. Steve Katz
The never-ending hi-tech search for fish
When the topic of finding the best fishing grounds comes up, some captains seem to have that 5th sense and can navigate their boat a productive spot by observing the conditions by eye along with chart data. On the opposite end of the spectrum, some captains won’t leave the dock without all the high-tech gadgets, such as satellite images, altimetry data and multiple on-board fish finding sonars. For most captains, there is a happy medium of local knowledge along with the right amount of technology to help guide the captain the most fertile fishing grounds.
Once you arrive at the fishing grounds, how do you know that the fish are there? Most of us use a finely tuned echo sounder/fishfinder/ sonar. What if there was something even better, a way to “see” if there are any fish around your boat in real time?
Traditional sounder
While many captains are familiar with sounder/fishfinder/sonar there are major technical differences on how they operate. The most basic fishfinder has a transducer that sends out sound waves in an inverted cone shape and then listens for its return to determine distance of an object, bottom or fish. The processor and display converts this sound image to a useful picture. 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, such as CHIRP, wide angle, forward looking transducers and faster and more detailed data processing. All of these improvements have made even the most inexpensive and high end fishfinders able to do a great job displaying the bottom structure and fish under the boat.
When it comes to commercial and government applications there are a few other types of sounder systems that have recently become more common in sportfishing such as multibeam sonar and scanning sonar. These systems are now in use within the sportfishing community due to their increased ability to accurately detail the environment below the boat and some even provide real-time data.
Multibeam sonar
A multibeam sonar has array has multiple sonar emitters in one fixed transducer. These multiple beams are digital “moved” to scan a wide angle, often 120-degree coverage using hardware and software, a traditional echosounder has a beam as narrow as 4 degrees. Examples of popular 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.
Scanning sonar
A scanning sonar works like your radar underwater; a transducer housing is lowered into the water from a storage tube within the hull of the boat. This internal transducer is rotated and tilted within the housing. The transducer can rotate up to 360 degrees, allowing an image to be created of the water area all around the boat. The tilt angle is also adjustable for varying water depths and task at hand. The Furuno “Searchlight” (CH-250) is a well know scanning sonar used in sportfish and commercial fishing boats along with the Koden units that are quickly gaining in popularity. While this technology may seem new, the original Furuno Searchlight has been in use for over 10 years and newer models are currently available.
The Omni
Technology has enabled the development of newer scanning sonar that does not need to rotate mechanically to capture the 360-degree area under the boat. The newest scanning, the Furuno Omni (CSH-8L MARK -2), sonar uses a sound dome (transducer) that deploys downward from the hull, like the Searchlight but consists of multiple stacked elements to transmit the sonar signal in all directions, virtually 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 out to about 1000 feet from your boat!
No matter what type of echo sounder/fishfinder/ sonar you use, learning how to adjust the settings for your fishing needs, and learning about the capabilities and limits along with properly interpreting the data can help you get on top of the leaderboard!
