Garmin Striker 200khz vs. 77khz

[wasabi_VA]

I remain confused over the 200kHz vs. 77kHz frequencies in my Garmin Vivid Striker 4cv. Just when I think I understand then the results I get on-screen turn it all upside down. I watched a popular video and literally made notes so I could carry them on the boat for reference:

 

200kHz - narrower cone, more power and more detail. 15⁰ cone

77kHz wider cone, less power/detail. 45⁰ cone

 

But I feel like I see the opposite in my images. For example image #1 has 200kHz on the left and 77kHz on the right. I feel like the 77kHz view is showing better returns/more detail. I don't understand why the supposed more powerful 200kHz view is showing weaker returns.

 

Picture #2 - same situation. Stronger returns/more detail on the 77kHz view and weaker returns with the 200kHz view.

 

Generally I do run CHIRP for both 200kHz and 77kHz, still had the same results. It makes me want to use the 77kHz for fishing these bottom fish (crappie) but according to the beam specs the fish may not be under my kayak with the 77kHz frequency since the beam is supposedly a 45 degree cone, or a 37'*0.83=30.7 foot wide view of the bottom. Instead I think I should use the 200kHz frequency with a 15 degree cone which gives me a 9.6 foot view of the bottom.

 

Why am I getting such better returns with the 200kHz beam?

 

[jhoffman]

If the 200 is on the left in both images youre not seeing weaker returns. Youre seeing target separation and better bottom composition 

[12poundbass]

I’m no expert on this subject, but from my understanding, with the lower frequency your cone is bigger which we already know. What you’re seeing on the higher frequency is the same couple of fish multiple times coming in and out of the cone which is why you see the clutter on the right screen.

 

The higher frequency has a smaller cone so this same couple of fish are in the cone less which creates less clutter. 
 

Also, the higher frequency pings faster than the lower frequency so it’s getting a return more frequently which also adds to the clutter and appears that there are more fish than there actually is. 

[Team9nine]

19 hours ago, jhoffman said:

If the 200 is on the left in both images youre not seeing weaker returns. Youre seeing target separation and better bottom composition 

This ^^
 

Some units will let you run a hybrid screen that combines both frequencies. Might see if your unit allows that, or some variation of. ‘Chirp’ often is the hybrid, so you might go with that and then play with power and scroll speed settings. Otherwise, it comes down to what is most important to you - target separation and bottom detail as mentioned above, or fish schools. Whichever it is, on a small unit like that, I wouldn’t split the screen. Pick a frequency and go with it full screen.

 

The “clutter” on the 77 deg screen is simply a larger cone picking up more fish, and then also exaggerating the arches - the wider the ‘cone,’ the more exaggerated the arch.

[wasabi_VA]

I don't consider the right side (77kHz) to be clutter. That looks like good fish returns. It's the left side (200kHz) where the returns look weak to me. Yes, there is more separation and I'm giving that though but I just thought the right side was a better looking return. But am unsure so thought I'd ask.

[Team9nine]

29 minutes ago, wasabi_VA said:

I don't consider the right side (77kHz) to be clutter. That looks like good fish returns. It's the left side (200kHz) where the returns look weak to me. Yes, there is more separation and I'm giving that though but I just thought the right side was a better looking return. But am unsure so thought I'd ask.

Better looking - yes, but more informative - no. Top pick demonstrates this well, where the right side is just a pile of tangled arches, but on the left, you can practically count how many individual fish are down there. Also look at the bottom definition difference. Try and drive over some cover like a brushpile or fallen tree and see how each shows up when making your decision.
 

Definitely play with settings until you get something you’re comfortable with for the way you fish. Every unit is different, and even different units from the same company will read dissimilarly. 

[Deleted account]

What I can't figure out is why fish hunch their backs like that and all swim at the same speed in one direction . Given those two options, I'd take the left with a skosh more gain.

[casts_by_fly]

1 hour ago, wasabi_VA said:

I don't consider the right side (77kHz) to be clutter. That looks like good fish returns. It's the left side (200kHz) where the returns look weak to me. Yes, there is more separation and I'm giving that though but I just thought the right side was a better looking return. But am unsure so thought I'd ask.

 

If you don't have the eyesight or attention span to watch for the smaller returns on the left you can always put the 77khz frequency on while searching for fish.  Just don't get so excited when it looks like a school of hundreds when it will actually not be as many.  If those are crappie, it looks like you must have your scroll speed really high also.  You're only doing 0.75 mph and those arches are very stretched left to right.  Crappie would ordinarily only have a short arch.

 

separate question- you're showing a 20V voltage on your screen.  What battery are you running it on?

[wasabi_VA]

I was going slow, probably only wind moving me as I fished.

 

Scroll speed is on auto and usually scrolling very slowly as I'm in a kayak. No more than 3.5mph and usually closer to 1.5 - 2mph while fishing.

 

I use a 20v lithium power tool to power my Garmin. Garmin specs say 10v - 20v.

 

 

[Johnbt]

I copied the following from somewhere 5 years ago. I neglected to save the site.

 

"When you fish 20 to 60 feet, your transducer frequency should be set to 200 khz. From 60 to 70 feet or so, you can change back and forth between 200 and 83 and see for yourself which frequency is showing the best detail. When you get into water deeper than 70 feet you will normally find that 83 khz will give you a better picture of the bottom.

The higher the frequency the better the detail but the easier the sound is absorbed by the water. This is why a lower frequency like 83 khz will show the bottom in deeper water but not in as much detail as you saw in shallower water with the 200 khz.

Ken Sauret
Lowrance Pro Staff"

[casts_by_fly]

1 hour ago, Johnbt said:

I copied the following from somewhere 5 years ago. I neglected to save the site.

 

"When you fish 20 to 60 feet, your transducer frequency should be set to 200 khz. From 60 to 70 feet or so, you can change back and forth between 200 and 83 and see for yourself which frequency is showing the best detail. When you get into water deeper than 70 feet you will normally find that 83 khz will give you a better picture of the bottom.

The higher the frequency the better the detail but the easier the sound is absorbed by the water. This is why a lower frequency like 83 khz will show the bottom in deeper water but not in as much detail as you saw in shallower water with the 200 khz.

Ken Sauret
Lowrance Pro Staff"

 

for a given power input that is true. However, transducer power output has been going up over time.  You could change your statement to mega hertz and 800 kHz instead of 200/83 now with the increased power input. 

[Johnbt]

I was trying to stick to the parameters of the question.

 

"200kHz vs. 77kHz "

[WIGuide]

Here's a way to visually interpret what you're seeing. Because the beam is smaller on the higher frequency you're seeing a narrow segment of bottom. Using the 200khz in the situation below you'd only be seeing 1 arch because only one fish is within the sonar beam even though there are more fish around. Switching to the lower frequency you would see more arches like you did in your first picture. As the water gets deeper, the cones get and larger so it's showing you more information on the same image. Looking at the specs on that transducer the 77kHz cone is a 45* cone and the 200kHz is a 15* cone. In the water depths of the first shot, the base of the 77kHz cone is roughly 31' in diameter where the 200kHz would be about 10'.