How To Use My Sounder Properly | Chirp Vs Dual Frequency

[Ryannnnnnnn]

Hello!

So I've had a sounder (garmin striker 4) on my kayak and have transferred it onto my boat (transducer mounted on transom). It's a 2d unit, and I find it quite hard to use but that's down to my lack of understanding. At the moment, I'm using it for depth but can't really say it's helped me catch fish at all - my success is purely down to repetition of fishing the same spots and knowing the structure around me.

I took it out to Somerset dam near Brisbane and caught nothing, and it's pushed me to try and research more on how to properly use my sounder. Have watched some videos and read lots of articles but am still stuck on the below questions (sorry if they're stupid!)

1. What's the difference between dual frequency and chirp? My unit features both of these. 200khz (15 degrees) and 77 khz (45 degrees). I understand both frequencies have their benefits and show a different radius. 
2. My unit has a split screen view for both frequencies that show the same picture in different detail. I thought chirp combines the frequencies into one? When using split screen am I using chirp or dual frequency?
3. When viewing split screen frequency, I see the same picture but in different detail. But I thought that the 77khz would give me a much wider area of view given it emits a larger cone? Confused as to why I would see the same area, unless the 77khz is zoomed to the area of the 200khz to show the same thing.
4. When I spot fish, by the time I drop my lure down the fish are gone. How do I know where to cast given it's a 2d image? If I spot fish, should I literally be dropping my lure down or casting out in some direction?

Appreciate any help you can share!

[Old Scaley]

Hi @Ryannnnnnnn. I am getting to know my new Garmin 93sv and have been looking at YouTube videos and other articles on line. Some are more useful than others.  This is one I found ages ago that is really useful in trying to interpret the sonar view. https://doctorsonar.com/blogs/educational-articles/12380345-lowrance-pros-corner-by-luke-morris. I think it predates chirp so it won’t answer that question but hopefully it will give you some idea.  Good luck, mate.

[Junky]

200 kHz is for shallow water. Up to 100m or thereabouts. It pings quicker than 77khz. 

By ping I mean the clicking of the transducer...similar to dolphins clicking when they're sounding for food.  

An easier way to look at it is 200khz pings every half a second......77khz will ping every second and a half. That's why your picture looks faded on 77khz compared to 200khz. The information is just not coming back as quick as the 200khz is. That is why it is more for deep water. 

You can hear the pings if you pour some water over a glass table top and sit the transducer in it. Power up the unit and listen to the clicking. 

 

 

 

The transducer sends out a click/ping. It then waits for that ping to go down, hit the objects and return to the transducer. Solids will return quicker...softer surfaces will absorb some of the ping. That's how it determines the density of the object and relays it into the coresponding color. Red is hard....yellow soft etc.

 

Sounders without chirp will only read 1 ping at a time. Chirp reads every ping all the time....hence the clearer picture. The sounder is processing so much more info with chirp. 

 

Splitting your screen and running the frequencies separate is not really going to help you. Running them together will because the sounder area is increased with the 77khz cone. If chirp is functioning then it will say it on the bottom of the screen around the kHz etc.

Chirp is worth it imo. 

 

 

If you split your screen, try the full view on one side and zoomed view on the other. I set my zoom at about 10m and leave the depth range on auto. It will then follow the bottom in a zoomed view and the full screen view will pick up anything higher up in the water. Generally do this in depths greater than 25m otherwise just leave the full screen view. 

There is also bottom lock. Bottom lock will leave the ocean floor flat meaning it wont drop down and come up on the screen as the depth changes. It just has a flat return and all reefs etc will rise off the flat bottom. Handy for picking up fish inside reefs etc. 

 

 

[Junky]

If you spot fish then the sounder has done its job. It is not going to tell you which direction they are travelling. That is why it is called fishing....not catching. 

Once you know the fish are there.. or around the area.....cast, burley, bait the crap out of it. 

 

It can take me sometimes 2hrs before I drop a line. I'll sound around till I get what I am looking for.....and after a while you'll be able to tell what fish are giving the returns. 

I can tell what most returns are just by the image on the screen. Snapps pearlies and reds have a very identifiable return.  That takes a while to get the gist of though but with time you will learn. 

[Ryannnnnnnn]

Thanks for the helpful replies.  most of my fishing is between 1 to 20 meters in water. Sounds like I'm best generally using the chirp 200khz setting. 

I've been thinking chirp sends a 77khz and 200 kHz frequency only, but I can see there's a 77khz chirp setting and also a 200khz chirp setting, which makes me think the 77khz setting sends a wave of different frequencies around  that low band, while the 200khz settings sends a wave of varied frequencies up towards the 200khz band. Does that sound right?