If you’re trying to decide between a dual beam and a tri beam sonar fish finder, to make sure you get the one that fits best to your needs, I hope this post will help.
First of all, this is how a dual beam and a tri beam works.
A dual beam sonar projects two concentric cone sonic beams into the water, directly under the boat, under the transducer, to be more specific. One is wider, with a 60° opening, and will help you find stuff faster, because it scans more water. However, the returns aren’t very sharp. The other sonic beam of a dual beam sonar is narrower, usually 20°, provides a sharper view, but evidently scans less water. So, as a general idea, as you sail along, you should scan the water with the wider beam, and once you find a point of interest, a spot with fish, a stump in the water or the brush that you’ve been looking for, switch on the narrow beam and have a better look to see where the fish are, or where would be best to place the bait.
Most of the fish finders, like the 386ci Combo, or the 898c SI Combo allow you to observe the returns of both sonars in split-screen. In general, all Humminbird fish finders that have Dual Beam Plus sonar allow you to do that.
A tri beam sonar fish finder projects three sonic beams:
– A narrow one, similar to the one in a dual beam sonar, which points directly under the boat, usually having an opening of 20°.
– Two other beams, usually with an opening of 35°, which flank the 20° beam, one angling slightly to the left and the other one to the right.
In general, all the fish finders that have a tri beam sonar have a 3-split-screen feature, allowing you to observe the returns of all three sonic beams simultaneously. So, if for example, a fish or an object is caught by the left beam, you’ll know for sure that it’s on the left of your boat, and you’ll know better where to place your bait or cast your lure.
In general, a tri beam sonar fish finder is more effective in shallow waters, up to 40-50 feet deep. A few of the models that feature a tri beam sonar are the PiranhaMax 180 or PiranhaMax 190c.
On the other hand, a dual beam sonar, depending on the model, is more useful in deeper water.