Dual Beam Transducers

A great question came up this AM on www.lakestatefishing.com that had to do with the depth reading on a flasher unit when comparing narrow beam to wide beam.  Essentially the question was "why does my flasher read deeper on Narrow Beam than it does with the Wide Beam?"

The answer is pretty simple but can be effected by a lot of factors thus complicating the situations some.  For those that are getting lost already certain flashers have what we call a "dual beam" transducer.  Basically you can either choose to view a small area of the water column directly under you or a larger version.  If you look at the picture at the top left you should be able to see what I am talking about.

So, now back to the original question.  When you go from wide beam to narrow beam you are obviously reading a smaller area underneath you. So, on wide beam your display is only going to show the shallowest spot in the cone, thus creating a dead space. In addition, on wide beam you are going to read any weed, rocks etc that may fall in the cone area, basically the shallowest solid point is going to be displayed at bottom on your flasher, even though there may be a deeper point in the cone.

When you change to Narrow Beam you are covering a very small area of the bottom and your unit is only reading what is directly under you. The narrow beam will give you the best picture of what is immediately underneath you and will eliminate and rocks, weeds or humps that may be near but not inside the smaller cone and thus giving you a more accurate depth reading directly underneath you.

When using your narrow beam you may want to increase the gain some. That is typical no matter what flasher unit you are using, you get better performance on narrow beam if you increase the gain some.  Despite increased output on most units at the transducer when the narrow beam is selected increasing your gain does help when using a narrow beam.

When I am fishing open water less than 20 feet I like to use my wide beam. The wider cone angle gives you a bigger window to see and allows you to see fish as they approach your bait from the sides which can be beneficial most of the time.  When I am fishing deep water, near weeds or cover or on deep drops you will want to use your narrow beam.  As mentioned earlier when you use a smaller cone angle you can eliminate all that "stuff" outside the cone that is giving your returns and focus a very small area directly under you.  In addition, you get very little "dead space" while using your narrow beam which is essential on steep drops or uneven bottoms such as large rods.
 

It is very common for ice sonar units or flashers to come with a dual beam transducer now.  In fact, once you get used to using a dual beam transducer it is hard to fish without.  The good news is all the new Humminbird ICE units come with a dual beam transducer so no matter what your price range is, you can enjoy this feature.