3) Real Time: Your sounder generates the picture on the right side of the screen and sends it left, one line of data at a time. The picture crawls across the screen at whatever speed the advance is set for, and ultimately draws out what was, or is, under the boat. If you are on anchor or tied to the dock, the whole picture shows what's under the boat. If you are under way and moving, most of the picture will be history, as far as what was under the boat. Remember, only the lines drawn at the far right show the real time of what is directly under the boat

4) The A-Scope: One of the most common questions I get in seminars has to do with what the A-Scope is and how to use it. I can certainly relate to the frustration, as in one manual for a very expensive sounder the factory definition says, “The A-Scope displays echoes at each transmission with amplitude and tone proportional to their intensities.” Some definition! It's no wonder many users never take the time to figure it out. It's actually relatively simple to understand A-Scope and very helpful to use.

When you turn on the A-Scope function, you split the screen into the regular display with the A-Scope on the right side. In the A-Scope section, what you see is an expanded version of each line of transmission. The colors parallel the ones your meter is using, that part is the same. In the definition, the word amplitude refers to the width of the display, with the darker colors (stronger echoes) being much wider than the weaker echoes.

With the A-Scope on, two things happen: Since each line is expanded to almost an inch wide, you get instantaneous information about what is under the boat without having to wait as the unit draws out the picture line by line. You get a fascinating kaleidoscope of moving color that is fun to watch no matter what's on the screen. I love the A-Scope function and use its instant access to real-time data as a constant reference.

5) Colors: Whether your machine displays only 8 or 64 colors, the basic principle is the same, the weaker targets are displayed in the softer blue, green and yellow scheme while the harder targets get into the oranges, reds and dark reds to nearly black. This makes it easy to distinguish between the pale pastel blue of a squid mark and the heavy dark-red display you'll see from the dense body and large air bladder of a big sea bass.

6) White Marker: Here's where the color setup gets fine-tuned. The white marker function let's you manually select one color to change to bright white. I usually select the darkest color since that is the one the machine uses to draw the actual bottom (and the bigger sea bass).

"By turning the bottom into stark, bright white, anything on or slightly above the bottom becomes very easy to distinguish from the actual bottom. This makes the white marker a very helpful feature!"

7) Advance Speed: Most of the newer meters use one of two displays to indicate the movement of the picture across the screen. Some use numbers on a scale to show speed, usually from one to six. The higher the number the faster the speed will be. Others use a fractional display like 1/4 or 1/2 which means, respectively, one line of data drawn for four actual transmissions from the transducer or one line for two transmissions.

Get the display moving too fast (2/1) and the picture becomes too spread out. Run it too slow (1/8) and the picture becomes too compressed to see good bottom and fish detail. I usually run my meter in the 1/2 position for a good representation our underwater environment.


8) Worms: These are one of my favorite sights when sea bass fishing. They might actually bring a rare smile to my face, as its usually just a short time thereafter and the rods start bending! The actual mechanism that spots the worm is simple enough. With the boat anchored and stationary, a slow moving fish that takes up residence in the beam for a long period of time will display continuously on the screen. As the boat rises and falls in the swells, the mark appears to undulate, and it looks like a worm on the screen.

sand bass

Sand bass on the local grounds often will mark like this, as will barracuda at times. Sea bass make classic, very distinctive worms as they will hang under a boat for long periods of time. Additionally, when they are on the move they often get in a line of several fish, following closely — nose to tail — in a chain.

Every sounder is a bit different and the new machines out there offer even more functionality, but the eight topics mentioned in this article represent the most commonly asked questions I hear. If you want to attend a seminar to get more details and see some great sounder shots, check the schedule on our website, www.PacificEdgeTackle.com.



Well-known California captain, writer, speaker and tackle shop owner, Capt. Mark Wisch has been helping anglers catch fish along the West Coast for decades. As an author, Mark has written three books, including “Between Two and Twenty Fathoms,” “In The Gray” and “Lessons from a Lifetime on the Water.” He's currently working on his fourth book, “Way Out West, a Private Boaters Guide to Fishing Offshore Waters.” Mark owns and operates Pacific Edge Tackle (www.pacificedgetackle.com) and manufactures a complete line of live bait tanks. He also specializes in outfitting sport-fishing boats with electronics and fishing equipment. Mark graduated from Cal Poly, Pomona, with a degree in marketing and currently resides in Huntington Beach, California, with his wife Chris and their dog Emma.