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Saltwater Side-Imaging Frequency Experience

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Saltwater Side-Imaging Frequency Experience

Old 04-16-2021, 08:39 AM
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Default Saltwater Side-Imaging Frequency Experience

Iím in the market for a new fishfinder/chartplotter/transducer setup after my Helix G2N died on me last year, and I have $1300 to spend thanks to the extended warranty I bought.

Iím pretty sure Iíve narrowed it down to the Garmin 94sv and Humminbird Helix G4N SI+, but before I make the decision Iím curious to hear othersí experience with the newer side imaging frequencies and processing.

Iíve seen a lot of people here and elsewhere talking about how ~800htz and megahtz (1000+) side imaging frequencies are practically useless in saltwater when fishing anything but very shallow, ~450htz isnt that much better, and the ~260htz frequency works best. Most of those comments seem to be in reference to finding structure, but for my fishing Iím more interested in fish or school identifying capabilities. I do a lot of chasing striper schools or live-lining bait in and around Boston Harbor, and being able to see a school of stripers 100ft to my left or right in 20-75ft of water is my priority (at least when it comes to side-imaging).

Am I wasting my money buying a unit+transducer that only runs 455+800htz, or 455+800+1000htz scanning frequencies?
Does anyone have good experience seeing fish in side scan at the higher frequencies?

Thanks in advance for any input!!
Old 04-16-2021, 09:33 AM
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Those depths will work with 455/800/1G .
260 is what I used from 80' to 150'+ to find structure but it would show fish too. Sorta.
Fish marked as white dots mostly as their swim bladders are what normally get seen with the 260 altho bigger fish and sharks would show shadows.
Old 04-16-2021, 10:42 AM
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Attenuation of sonar frequencies increase by frequency, but for high frequencies saltwater is not worse than freshwater. Attenuation caused by absorption in saltwater is for frequencies of 1MHz and above the same as for destilled water.

​​​​​​Other sources of attention or distortion will in a lot of locations give additional attention, but in cold clear saltwater, like in a Norwegian fjord during winter, the attention of 1MHz or higher frequencies will be the same in saltwater and freshwater.
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Old 04-16-2021, 12:15 PM
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Originally Posted by Seaway85 View Post
for my fishing I’m more interested in fish or school identifying capabilities. I do a lot of chasing striper schools or live-lining bait in and around Boston Harbor, and being able to see a school of stripers 100ft to my left or right in 20-75ft of water is my priority (at least when it comes to side-imaging).

As to your requirement of seeing strippers 100' out to the side with side scan........ You would be lucky to see good structure at 100' to the side.
Seeing fish out that far is not really what is generally done wiht most side scan systems.

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