Transducer question

[spagatti]

So I have acquired a Garmin 400c, new in the box that my in-laws bought a few years ago and never used. My question is about the transducer. It has dual frequency and a dual beam setting. I mostly fish very shallow, 12 feet is deep in the lakes I frequent. I'm thinking dual beam serves my purposes best but I have no idea what I could gain from dual frequency.
Any help you guys can offer would be appreciated.

 

[TNtroller]

If the dual beam means capable of 83/200 frequencies, then use the one for shallow water, sorry but I can't remember which is best for which. I'm thinking 83 is better for shallow water like 12' or so.

 

[Team Colibri]

It's been a while since I looked at this unit, but from what I remember you have dual frequensy OR dual beam depending on your tranceduser. The double frequensy one is 50/200 kHz with coneangles of 45/10 degrees according to Garmins way of measurring coneangle. The double beam is 83/200 kHz with coneangles of 45/15.

Double frequensy basicly means you can run both 50 and 200 kHz in splittscreen, ie half the screen showing 50 and the other half showing 200 kHz. I'm guessing this is the version you have, as most used the dual beam on their front mounted trollingmotors, and the main point of it was to have a flasher as well as a graph.

If it is the double frequensy version you have, I would recommend running it in splittscreen until you are familiar with the unit. 50 kHz has the widest cone, and will therefore cover more water/ ground beneath your boat, but 200 kHz gives better resolution/ detail. (But 10 degrees coneangle is really tight, so you will probably end up using 50 kHz for searching for fish and 200 kHz to study bottomstructure.)

 

[spagatti]

Thanks. I do have to set it at dual frequency or dual beam.
Dual frequency does have a spilt screen option, but on a 4" screen that's a feature that's hard to use.