Yes we call them depth sounders and not fish finders because a suspending plastic bag gives a fish symbol as well. Depth sounder is a better name while it works with sounds just like Dolphins and Bats do with their sonar its sending out a sound and measures the time it takes to get back and then recalculate to a distance. If you use your sounder serious, you use it to scan the bottom and learn about hardness, rubbish or mussel banks  that’s where the fish are. To see a fish on the screen is oke but not necessarily. Tip, make a photo from your screen if you see a thick clear grayline and then make a test. Drop a line with a weight to the bottom and feel. Is the bottom hard or soft. Do the same on a spot without a thick grayline.

Soft grounds will absorb the sound and less echo will return. Shut off Fish ID, very important to get a accurate  image showing banana like curves if you hit some fish. The size of the banana image is NOT the size of the fish. If you just hit the tail or head in your depth sounder range, it will give a small curve but the fish could be your new PR. A Big banana is not always a big fish but could be a school of some small fish swimming close together. If I hit the fish on the image from tail to head it will give a nice banana and showing a large fish. If I hit the fish from the side it will give a very poor banana showing a very small fish. So the angle you hit the fish will be on influence of the image on your screen.

If you have a choice in the angle of the transducer, I advise you to take the smallest angle ( 20 degrees ) because you get the most accurate image, What use does it has if you see a fish on your screen but not knowing if the fish is 10 meter left or right from your boat. It’s better when you see a fish, this fish is close to your bait. Of course this is when you fish strait down or when you are trolling baits. If you drift and cast to hotspots, it can be an advantage to have side scan transducers.

Tight lines

Bert