Thread: sonar coverage

The biggest difference in these 2 choices is the HB 346c DI has two separate 2d (cone shaped) sonar beams and two separate DI (fan shaped) sonar beams..

Whereas the Elite 4x only has two separate 2d (cone shaped) sonar beams...

Beam angles are more difficult to compare apples against apples because brands "measure" their beam angles differently...

HB measures their beam angles at -10db...
Low measures their beam angles at -3db...

All sonar beams (All brands) are strongest at center with "ever-decreasing" strength as they emit outward in their designed beam shape...(that's just how "soundwave theory" works)..

If one measured the beam angles at the very same -"xx"db...they would be within a few degrees of the same...

I would suggest deciding on which sonar "technology" (2d/DI/SI) is going to benenfit your fishing style most and then compare units that offer those chosen sonar technologies (2d/DI/SI)..

Because each technology (2d/DI/SI) has a different sonar beam shape...this makes each, in its own right, good at certain situations but not so good in others...

2d gives a "cartoon like" display image of things under the boat...
DI gives a "picture like" display image of things under the boat and out to the side several feet..
SI gives a "picture like" display image of things under the boat, out to the side 100+ fewer, and which side of the boat...

2d is good for sitting over structure as in vertical jiggin...
DI is good for "passing over" structure to see what the structure looks like...
SI is good for finding new structure out to the sides of the boat...

Rickie

Thanks Rickie,

Forgive my ignorance, so then how do frequency and db relate in terms of beam angle? and does frequency affect beam angle? I've read in a number of places where poster prefer 83khz over 200khz because the beam angle is wider and, thus, you can see more of what is under your boat.

Regarding your suggestion of determining which technology will benefit me most........ I'm not sure about that.......actually, that was the nexus of my question....so any additional assistance is appreciated.

Jimmy

Originally Posted by rnvinc

The biggest difference in these 2 choices is the HB 346c DI has two separate 2d (cone shaped) sonar beams and two separate DI (fan shaped) sonar beams..

Whereas the Elite 4x only has two separate 2d (cone shaped) sonar beams...

Beam angles are more difficult to compare apples against apples because brands "measure" their beam angles differently...

HB measures their beam angles at -10db...
Low measures their beam angles at -3db...

All sonar beams (All brands) are strongest at center with "ever-decreasing" strength as they emit outward in their designed beam shape...(that's just how "soundwave theory" works)..

If one measured the beam angles at the very same -"xx"db...they would be within a few degrees of the same...

I would suggest deciding on which sonar "technology" (2d/DI/SI) is going to benenfit your fishing style most and then compare units that offer those chosen sonar technologies (2d/DI/SI)..

Because each technology (2d/DI/SI) has a different sonar beam shape...this makes each, in its own right, good at certain situations but not so good in others...

2d gives a "cartoon like" display image of things under the boat...
DI gives a "picture like" display image of things under the boat and out to the side several feet..
SI gives a "picture like" display image of things under the boat, out to the side 100+ fewer, and which side of the boat...

2d is good for sitting over structure as in vertical jiggin...
DI is good for "passing over" structure to see what the structure looks like...
SI is good for finding new structure out to the sides of the boat...

Rickie

Beam angle is definitely a partial product of frequency...in that...generally..lower frequencies have wider beam angles than higher frequencies...

This is just general criteria of sound wave theory in that lower frequencies expand farther from the strong center emission point before their "ever-decreasing" strength gets to the -10db point...

What I was trying to stress is that the advertised beam angles of different brands cannot be used as a criteria "that this brand advertises wider beam angles at 83kHz than this brand does...yada yada.."

They measure them differently..

But in reality they both produce about the same beam angles at the same 83kHz frequency...
And they both produce about the same beam angles at 200kHz...

Rickie

Originally Posted by rnvinc

Beam angle is definitely a partial product of frequency...in that...generally..lower frequencies have wider beam angles than higher frequencies...

This is just general criteria of sound wave theory in that lower frequencies expand farther from the strong center emission point before their "ever-decreasing" strength gets to the -10db point...

What I was trying to stress is that the advertised beam angles of different brands cannot be used as a criteria "that this brand advertises wider beam angles at 83kHz than this brand does...yada yada.."

They measure them differently..

But in reality they both produce about the same beam angles at the same 83kHz frequency...
And they both produce about the same beam angles at 200kHz...

Rickie

Maybe I should say that a little differently...

If you measured beam angles of each brand at -10db...the 83 would be about 60° and the 200 would be about 20°...(like HB advertises)
If you neasured beam angles of each brand at -3db...then either brand could say "up to 120/60°...(like Lowrance advertises)...

Both are true...neither are lying...both are misconceiving because most "average joe fishermen" just don't know exactly how wave theory works in the first place....and brands use this as a way to make their brand look more attractive to potential buyers...

Because there is no "industry standard" of how the beams must be measured ...the brands can say whatever they like to make you think they are better than the other brand...as long as their statement advertisement stays within the confines of how basic "soundwave theory" occurs...

Just remember most any brand's 83kHz cone shape sonar beam 2d is going to be about 60°...
And most any brand's 200kHz cone shaped 2d beam is going to be about 20°....

Your knowledge of what you hear about those would rather have the 83kHz 2d sonar beam are correct ...in that the 83kHz cone shaped 2d sonar beam is wider (most any brand)..so it will show fish echoes farther out from the center of the cone shape than a 200kHz 20° 2d sonar beam...(most any brand)....

Rickie

Rickie,

Thanks again for the instruction.........

So, in the two models I've listed above............the lowest frequency for the 2D sonar on the 346c is 200khz, while the elite 4x is 83khz....... can I assume then that I'll get more coverage with the Elite? I guess if I move the HB -10db number to -3db on the Lowrance.......the angle of 28 degrees (@200khz) will increase to around the 60 as on the Lowrance? 28 to 60 to 120....... that's a huge difference.

For me I can see using DI (or DSI) looking for stumps or dropoffs or underwater hills..........but I can also see us using that 2D sonar for jigging at the correct depths.

Things really should be standardized so that good comparisons can be made.

So, (based on your most recent email)................ If I want wide coverage.....I'd have to make sure I have 83khz no matter what brand....... 60 @ 83khz is much different that the 20 @ 200khz (lowest on the HD). If you're anchored up........... it would seem that is the way to go unless you have a couple of units.

Originally Posted by bradahj

Rickie,

Thanks again for the instruction.........

So, in the two models I've listed above............the lowest frequency for the 2D sonar on the 346c is 200khz, while the elite 4x is 83khz....... can I assume then that I'll get more coverage with the Elite? I guess if I move the HB -10db number to -3db on the Lowrance.......the angle of 28 degrees (@200khz) will increase to around the 60 as on the Lowrance? 28 to 60 to 120....... that's a huge difference.

For me I can see using DI (or DSI) looking for stumps or dropoffs or underwater hills..........but I can also see us using that 2D sonar for jigging at the correct depths.

Things really should be standardized so that good comparisons can be made.

I agree standardization would be nice ...but....

Anyway..notice in my previous posts I mention "Generally lower frequencies produce wider beam angles"...

Frequency is not the only criteria that determines beam angle....shape of the piezo element is a part of the equation also...

For some reason HB decided to make an "off the wall" beam angle xducer in their DI units...a 455 kHz 16° cone shaped beam and a 200kHz 28° cone shaped beam...

I have yet to hear a reason for this decision by HB....maybe it was for walleye fishermen who want good target separation from bottom detail...I don't know....

The 2d cones in these HB DI units are going to cover less bottom than most any other "conventional units" that advertise 83/200kHz 2d sonar beams....

So, in effect the Elite 4x in this case would be closer to the industry "norm" of the 83kHz being about 60° at -10db...

Whereas the HB DI unit "widest" cone shaped 2d beam is 28° at -10db...

You could always compare the HB 386ci Combo....( doesn't have DI but the 2d cone shaped beams are more comparable to the Elite 4x.... In that the 386ci Combo has more "conventional" 2d cone shaped beams of 83kHz at 60° and 200kHz at 20°... )

Rickie

But also remember that in the DI version of that unit you also have the 75 degree wide 455kHz DI sonar beam. This will be wider than a 60 degree wide 83kHz sonar beam and will be able to show smaller sonar returns with more definition due to its use of a higher frequency. That 75 degree beam will cover an area approximately 15.3 feet wide for every ten feet of water depth (Water Depth X 1.53). A 60 degree sonar beam will cover an area equal to the water depth (Water Depth X 1.00).