“Smarticals” LOL!

The decibel is the unit of measurement that is used to express the sound pressure level of the sonar (strength of the sonar whether you are talking about the transmitted sonar or the returned echoes). This is like using Lux or candlepower to measure the amount of light from a flashlight. To advertise specifications about that flashlight, you have to pick some point to measure that flashlight beam width at. Some would use the half power point (which is -3db for sonar). You than measure the width of the flashlight beam and calculate the angle. This would be the beam width of the flashlight beam at the point that the light on the outside of the beam is half as bright as it is in the very center of the flashlight beam (the very center being the brightest part of the flashlight beam). The problem with this is that you can see objects in the area that has less than half the brightness of the center beam, so shouldn’t you use a more realistic measurement point? Basically this is what Humminbird does with our sonar. Instead of using the half power point we use one that we feel more accurately reflects what you are seeing on the screen of your fish finder unit.

Hope that helps clear it up for you Cache22.