Your 200khz is correct for shallow water to at least 150 ft. in fresh water. Below that you would set at 450khz and I'm not sure what depth it will read at at that setting. Set at 200 khz. scroll speed as fast as it will go, sensitivity up until the screen starts blacking out with noise then back it off till it clears. If your fishing no deeper then lets say 30 ft. your setting will always be good for you even in shallow water.

 

Scroll speed should roughly match boat speed. If you crank your scroll speed, anything you mark will look like a tiny dot on the screen.

The lower the frequency, the deeper the water. Deep water transducers are 50khz or less. Higher frequencies for more definition and deeper water.

On that Helix unit, make sure you enable Max Mode or the images are really grainy at best. Looks like 16-bit technology without it. Friend has one and he was ready to take it back before he found that setting.

This guy explains everything pretty well. 200khz doesn't give you much of a cone as you can see.

http://www.jasonhalfenoutdoors.com/downimagingfish.html

 

Thank you for the input. I have had the sensitivity exactly as you described, but the scroll speed is only at 5/10. I will try and raise that and see what it does.
-Is there a boat speed that is too slow for marking fish?
-Should I be able to mark fish trolling at .8-2.8mph?
-could it be that it is hard to see the fish on a helix 5 being that I have been running split screen between di and sonar and the screen is already small as it is?

Sorry for all the questions I've been playing with this thing since may and it always seems like I catch fish that I am not marking.

 

I will definitely try the max mode setting, I think hummingbird may call it switch fire? My images are exactly how you describe, grainy at best. Also the diagram you showed was exactly what I was afraid of. I read article on humminbirds website similar to the article you posted showing how fishing in 20fow with a 20 degree cone only produces a 7ft diameter circle on the bottom. I looked at specs for my helix 5 di unit and they are:
-Standard Sonar Coverage:16°, 28°, 45° & 75° @ -10db
-Standard Sonar Frequency:455/800/200/455 kHz
does that mean at the 200/455khz I am getting a 75 degree cone? I do not have the SI model

Maybe since I paid off my boat this week I have an excuse to look into a sidescan unit that will give me much wider coverage

 

That was the advice I gave my buddy on his Helix unit.. Hock it and get some side scan heh. Now to your question about the coverage listed there. I'm not real sure. A quick call to Humminbird should straighten it out. There may be more to it than we realize. There almost has to be because that 20deg cone is pretty much a joke.

1-800-633-1468 is their customer service number.

 

I couldn't agree with you more about the 20 degree cone being a joke. I will call hummingbird today or tomorrow and post a solution (hopefully). Thanks everyone for the advice

 

Your scroll speed has nothing to do with the boat speed, the reason is to separate targets and not stack one on the other. The 450 khz has always been used to look in deeper water in your Lowance units, unless something has changed. imagine seeing a school of fish with a 65 degree or 85 degree angle, it would be one blob unable to separate each target. So for example when you look at a school of baitfish "a blob mark" you'll also be seeing a blob of walleye unable to separate. The hooks you are hearing about is a fish that enters your sonar at distance...bottom of the hook...gets closer..arch of the hook...gets farther as you pass.. bottom of the hook..

 

Humminbird disagrees:
"Chart Speed Setting – if the Chart Speed is set too high, the depth sounder will draw an elongated arch that may not be recognizable as an arch. With the Chart Speed set at a high setting, the arch may be spread across several screens. With the Chart Speed too low, the depth sounder may be drawing the arch but it may just look like a ‘blob’ of pixels shown all together. Again, try matching the boat speed to the Chart Speed setting. During field trials we have gotten reports that the depth sounders were not showing fish as arches. Setting the Chart Speed to a lower, slower setting ‘fixed’ the reported concern."

http://www.humminbird.com/Category/Support/FAQ/FishArches

Heres another good writeup regarding Humminbirds chart speed:
https://www.in-depthoutdoors.com/community/forums/topic/hbird_783389/

If you are talking about Lowrance units, I don't even think thats a setting you can adjust. Its automatic.

Regarding transducer frequencies. Lower frequencies travel further. Higher frequencies dissipate quicker. Whales and other sea creatures use ultra low frequencies to communicate long distances underwater. They use higher frequencies much like we use sonar. Think bats. Higher frequency, better definition, lower = travels further, larger cone.


http://www.raymarine.com/view/?id=197

"
200 kHz (high)

200 kHz works best in water under 200 feet/60 meters and when you need to get an accurate reading while moving at faster speeds. High frequencies give you greater detail to detect very small objects but over a smaller portion of water. High frequencies typically show less noise and fewer undesired echoes while showing better target definition."

"
50 kHz (low)

For deep water, 50 kHz is preferred. This is because water absorbs sound waves at a slower rate for low frequencies and the signal can travel farther before becoming too weak to use. The beam angle is wider at low frequencies, meaning the outgoing pulse is spread out more and is better suited for viewing a larger area under the boat. However, this also means less target definition and separation and increased susceptibility to noise. Although low frequencies can see deeper, they may not give you a clear picture of the bottom.

Mud, soft sand, and plant life on the bottom absorb and scatter sound waves, resulting in a thicker bottom image. Rock, coral and hard sand reflect the signal easily and produce a thinner bottom display. This is easier to see using the 50 kHz setting, where the bottom returns are wider.

A rule of thumb would be to use the 200 kHz setting for a detailed view to about 200 feet and then switch to 50 kHz when you want to look deeper. Better yet, display both views side-by-side on a split screen for both perspectives."

http://www.lowrance.com/en-US/Support/Transducers/

"

• What frequencies do I need?
  • Here is a quick breakdown:
    • Low CHIRP or 50kHz—Lower frequency means higher power for deep-water fishing.
    • Medium CHIRP or 83kHz—Specifically designed to give the widest coverage area, 83 kHz is ideal for watching a bait under the transducer in shallow water.
    • High CHIRP or 200kHz—Higher frequencies display a higher resolution image making it easy to discern fish from structure or structure from the bottom.
    • 455kHz—Built into StructureScan HD and SpotlightScan, 455kHz allows for scanning of a large range with picture-like detail.
    • 800kHz—Also built into StructureScan HD and SpotlightScan, 800kHz yields less range but even higher resolution detail than 455kHz."

 

I still haven't gotten a chance to speak to humminbird about this. The open at 8:30 and close at 4:30, my job overlaps the time they're open.
Massillonbuckeye, I've seen that it states that 200khz is good for shallow water target separation, but if I'm only fishong 20fow and the cone diameter at the bottom is 7 feet. That would just be really inefficient in searching for fish. Unless the helix 5 has a wider cone angle with 200khz than 20 degrees.

 

http://www.humminbird.com/Products/HELIX-5-DI-GPS/

From what I can gather from the manual, the DI transducer beams are wide but very thin front to back. The down imaging beams can be operated at two frequencies, 455(75deg cone) and 800khz(45deg). Select 455 for best overall image quality and depth, select 800 for sharpest image. It goes on to say the transducer also used Conical beams to provide data in traditional 2D. So in effect, its emulating the 2D. Select 455khz for a narrowly focused 16deg center beam or select 200khz for a wider 28deg beam.
So I'd probably set it on 455khz for the 75deg cone. They say that 60deg gives you bottom cover equal to depth. So 75deg cone should be a bit better than that even. 800khz would be a little shy of that. maybe 15-18' coverage in 20 fow.

So that makes a bit more sense. Those narrow cones and the 200khz only comes into play when you are using 2D mode either on its own or as split screen.


http://www.humminbird.com/Products/HELIX-5-DI-GPS/

 

Awesome, that makes a lot more sense now I think. I'm hoping to get to pymatuning this weekend for some walleye trolling. If I do I'm going to try switchfire max mode and give the different frequency settings a try and see what happens. Thanks everyone!

 

I managed to call humminbird today. Once the customer service tech support finally answered I was able to get confirmation of the cone angles.
The 455/800khz is for down imaging with the 455khz having a 28 degree cone angle and and the 800 khz having a 16 degree.
The 200/455khz is for dualbeam plus(sonar) and the 200khz has a 75 degree cone and the 455khz has a 45 degree cone.
I will definetly correct these settings for my next time out. I didn't realize the different angles availible while I am running split screen on di/sonar.

 

The diagram posted above is for the HB core SI units ...

Here is the diagram for the HB core DI units ...


As a general rule in any Sonar technology (2d, DI, or SI) ...

*Lower frequency gives more range with less detail ...
*Higher frequency gives more detail with less range ...



The higher frequency has less range because the sound pulse is more readily absorbed in the water (attenuated) with the wavelengths spaced closer together ...

Rickie