# Humminbird Helix 10 Mega Chirp Side Imaging G2 ?



## Ruminator (Apr 6, 2004)

Anyone know what the degrees in the water column are that the transducer beams cover?

If straight out from the transducer to the sides is 0 degrees, and straight down is 90 degrees; where in that range is covered by side imaging?

Does Humminbird state this anywhere?


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## kycreek (May 31, 2006)




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## Ruminator (Apr 6, 2004)

Wow, thanks Mark. That gives a clear representation.

According to this, SI will show bass (any fish) along the shoreline, a pontoon or a downfall in the top 18" of the water column that is within the distance range selected.
Actually I guess the transducer depth in the water may present an upward boundary for sonar responses; unless it shoots a couple degrees above the transducer itself which could capture the the water column to the water surface.


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## kycreek (May 31, 2006)

I found that while researching the Chirp Mega. I just upgraded to a Helix 9 Mega Chirp G2N myself.


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## Ruminator (Apr 6, 2004)

Nice upgrade. 
I found the pdf. you posted and downloaded it.


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## RMK (Feb 21, 2017)

Ruminator said:


> Wow, thanks Mark. That gives a clear representation.
> 
> According to this, SI will show bass (any fish) along the shoreline, a pontoon or a downfall in the top 18" of the water column that is within the distance range selected.
> Actually I guess the transducer depth in the water may present an upward boundary for sonar responses; unless it shoots a couple degrees above the transducer itself which could capture the the water column to the water surface.


i m seeing that it states SI shoots out at 86 degrees. so slightly less than straight out from the transducer. so the farther away left and right you are from the transducer the deeper in the water column your top edge will be. so seeing a bass in the top 18" of the water coloumn along the shore is probably a no....?? also having your SI transducer mounted as shallow as possible would be a plus. skimming the surface. mine is deep on the transom. i m kind of asking. i m very much still learning. i am currently unable to use my SI to see fish under pontoons or on lifts/docks in 5-8 fow. to me it seems like this should be a very reasonable task to ask of my finder, but like i said, currently i m not able to do that.


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## kycreek (May 31, 2006)

Still learning & playing myself. Just the ability to identify stumps along a creek edge is going to be nice. I have DI on the front but the SI at an idle is nice. Found stumps locally that I never knew were there even at low water.


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## Ruminator (Apr 6, 2004)

RMK, unless I'm mistaken it looks like all of the degrees stated in the diagram are a total number of degrees that is covered by that particular type of beam.

For example, the 20 degree cone doesn't begin at 20 degrees.


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## Scum_Frog (Apr 3, 2009)

My new boat came with Birds and im a Lowrance guy so im learning all this as well. I went with two helix 9 g2n's on the bow with 360 and g3n helix 12 mega+ on the console.....learning all this will be different but cant wait to see the SI at work!


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## RMK (Feb 21, 2017)

Ruminator said:


> RMK, unless I'm mistaken it looks like all of the degrees stated in the diagram are a total number of degrees that is covered by that particular type of beam.
> 
> For example, the 20 degree cone doesn't begin at 20 degrees.


i see that now. my bad. i have some settings to play with and possibly even try some different transducer positions.


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## RMK (Feb 21, 2017)

Scum_Frog said:


> My new boat came with Birds and im a Lowrance guy so im learning all this as well. I went with two helix 9 g2n's on the bow with 360 and g3n helix 12 mega+ on the console.....learning all this will be different but cant wait to see the SI at work!


sounds like a very sweet set up! someday......


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## Scum_Frog (Apr 3, 2009)

I am hoping so but it is going to be a lot to learn as well.....excited but nervous!


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## Ruminator (Apr 6, 2004)

Personally I'd get the shoreline just within side beam distance and see if you can pick up a fireplace log weighted to float 6 to 8 inches below the surface.
I'm curious to see that for myself. Where will it show up on the screen?

I have to wait though, I need to get my unit installed. 

Man, ... $92.00 for the R-A-M mount!


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## RMK (Feb 21, 2017)

I think 92 is slightly cheaper than what I got mine for. Not sure if you areally familiar with the smaller $50 ones for the helix 7 and down size but the bigger one for the 9 and ups seems like it will be much more sturdy and bigger ball


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## BNiemo (Mar 28, 2019)

Just picked up a helix 5 chirp and I guess I m still not grasping the concept of si. If I m looking to starboard, is it showing me from the centerline out to starboard or just the starboard side?


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## rnvinc (Jan 14, 2015)

Advertised beam angles are a misnomer in the Sonar field because there is no "industry standard" for measuring Sonar beam angles ...

Brand advertised beam angle specs are a basic measurement of how much of the sound pulse has dissipated over a certain distance ... HB measures -10db which means "at what angle the sound pulse has dissipated to 1/10 it's original strength". Other brands measure -3db which means "at what angle the sound pulse has dissipated to 1/2 it's original strength" ...

It's important to understand that the Sonar sound pulse traveling thru the water doesn't travel to the "advertised beam angle" spec - and then just stops ... The sound pulse continues until it completely dissipates to 0db (no sound) ...

Any object (with sound reflective enough qualities) outside of the "advertised beam angle" spec can still reflect enough of the sound pulse to create a "display- able" echo on the screen ... This can mean a hard object or an object at an angle that reflects sound back to the xducer well ...

Now all this tech speak is not as important as understanding the basic general iotas of HB SI beam angles ...:

*455kHz covers from the water's surface to past vertical under the boat ...
*800kHz covers from about 30° from horizontal to past vertical under the boat ...
*1200kHz MEGA covers even less from horizontal to past vertical under the boat ...

(And as mentioned a hard object or very reflective object outside the 800kHz or 1200kHz advertised beam angle can still create an echo) 

AFAIK the other brand (L) has never advertised their imaging beam angle specs  ...

I think Garmin does ... But I don't know the specs ...

Rickie


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