Classic bass-fishing destinations like Toledo Bend Reservoir and Lake Sam Rayburn had a lot more standing timber in them back in the 1970s. In fact, once you got above their lower basins the only way to get around was to follow the many boat lanes cut through the trees.
Schools of bass used these boat lanes, too, as cover-free areas where they drove schools of shad to the surface in feeding frenzies.
The sight would raise the hair on the back of my neck, and I wasn’t alone; chasing these “schooling” bass in the boat lanes became a popular way to fish. The fish crashed to the surface, and then almost before you could cast they went deep again, leaving you wondering which direction to fire your lure until they popped back up.
To make matters worse, the fish often reappeared beyond the reach of your longest cast. These boat-lane bass were responsible for teaching enterprising Texas and Louisiana anglers to use sonar sideways.
Most of us had puck-shaped transducers clamped to the bottom of our bow-mounted trolling motors with automotive radiator hose clamps. Some of us wrapped our motors with several layers of black electrical tape to prevent scratches that would rust, and left those clamps just loose enough to let us rotate the transducer to the side of the motor.
How far to the side depended on the particular motor and transducer; moving the transducer too far to the side caused our flashers’ screens to light up with echoes from the underside of the water’s surface. Not rotating it far enough to the side wouldn’t let us see echoes from the fish as they ripped through the sub-surface baitfish, and left us blind as to which way the school was moving.
One entrepreneur started selling a metal transducer bracket that attached to your motor and let you adjust your transducer’s angle with what looked like a lawnmower’s throttle cable. This pointed the transducer and the motor in the same direction, and could be used while the motor was running.
The “semi-loose clamp” method the rest of us were using meant we had to turn off the trolling motor and search for fish with the transducer on the side of the motor.
Comparatively speaking, those were sonar’s dark ages, and we would have given a lot to have something like Lowrance’s new SpotlightScan sonar.
If you have a cable-steered, bow-mounted trolling motor and either a Lowrance HDS Gen2 or HDS Gen2 Touch sonar unit, you can attach the new SpotlightScan transducer to your trolling motor and scan the water around your boat for fish and structure.
The transducer scans an area about 30 degrees wide, straight ahead in the direction the motor is aimed. The 30-degree beam spreads 15 degrees to either side of your motor’s nose cone. It doesn’t scan a cone-shaped area like our homemade rigs did; it scans an area shaped more like a slice of pie.
Vertically speaking, the surface of the water is the upper edge of the scan, and a line either 30 degrees or 45 degrees down from the surface is the bottom edge of the scan area, depending on the operating frequency selected.
The transducer scans this “pie slice” area with a tall, extremely narrow beam similar to the beam used in Lowrance’s StructureScan technology.
SpotlightScan can operate at either 455 kHz or 800 kHz. For you tech-heads, the maximum sonar range is about 100 feet at 800 kHz and 200 feet at 455 kHz (Lowrance states 150 feet as an average maximum reach).
The sonar beam’s signal width is 1 degree at 800 kHz and 1.5 degrees at 455 kHz. From top to bottom, the beam height is 30 degrees with 800 kHz and 45 degrees with 455 kHz. For you non-tech-heads that means you get less range but more detail when using 800 kHz and more range but less detail when using 455 kHz. You also see a bit deeper as you scan to the side with 455 kHz.
Not only can SpotlightScan sonar keep up with boat-lane bass, you can pinpoint fish and fish-holding structure ahead of and around your boat without disturbing the areas you want to fish. It gives you picture-like screen images similar to those delivered by Lowrance’s StructureScan and DownScan Imaging features. In fact, SpotlightScan transducers also include down-looking elements for vertical DownScan Imaging, as well as conventional broadband sounder images so you don’t have to add more transducers to use those types of sonar.
The streamlined SpotlightScan transducer works with any cable-steered foot-controlled motor but not with hand-steered or electric-steering motors. It clamps to the bottom of a motor with that old familiar hose clamp, and its cable must be routed up the outside of the motor’s shaft. A mechanical feedback sensor mounts under the foot pedal to tell the HDS Gen2 unit which direction the motor is pointing and the transducer is looking.
The foot-pedal sensor plugs into your NMEA 2000 network, and if your boat doesn’t have one Lowrance offers a NMEA Starter Kit (part number 000-0124-69) so you can install one.
The SpotlightScan transducer cable splits into two cables, and if you have a Gen2 Touch unit, one cable plugs into its StructureScan port and the other plugs into its Broadband Sounder port. If you have a non-Touch Gen2 model, you’ll need to install Lowrance’s SonarHub module ($599) between the transducer and the unit. This module has both StructureScan and CHIRP sonar technologies built in.
The transducer’s twin scanning beams provide fast refresh rates, giving you quick updates on the 30-degree-wide area you’re interested in because it doesn’t have to wait for a full 360-degree scan. Beam indicators or “spokes” visible on the HDS Gen2 display show the width of the area being scanned and exactly where the transducer is aimed.
You can use a split-screen display to see the SpotlightScan view along with other sonar views, or dedicate the whole screen to just the SpotlightScan picture for maximum visibility.
SpotlightScan sonar is scheduled to reach dealers in February of 2014 and to sell for $499. For more information, visit www.lowrance.com.