Using fishing depth finding sonars units for metal detecting

49er12

Bronze Member
Aug 22, 2013
1,238
1,630
Rolling Rock, Pennsylvania
Detector(s) used
Minelab xterra, Whites DFX, Notka Makro Simplex. Folks the price don’t mean everything, the question is are you willing to put in the time to learn the machine, experience will pay off I guarantee it.
Primary Interest:
All Treasure Hunting
I’ve notice some of these units hummingbird and others if used correctly you can see structures and old foundations in local lakes and rivers, if anyone currently uses these units for this can you please tell me the better units and features that discovered such great photos, videos thankyou
 

I’ve notice some of these units hummingbird and others if used correctly you can see structures and old foundations in local lakes and rivers, if anyone currently uses these units for this can you please tell me the better units and features that discovered such great photos, videos thankyou
New one for me have to give it a gander gl my friend
 

Look into "sidescan" capability.

In silty or marl type bottoms , bottomline/greyline(?) sensitivity adjustment capability can help. A unit without it you can for example , not notice fish hugging bottom.
Too great of sensitivity on everything can be self defeating though. That's why being able to adjust helps.

Electronic isolation of a unit helps. And some will sense other units nearby by interference. Some may have aftermarket or options for filters. Or different settings. You don't want to hear your motor fir instance. Or radio wired to same power source. At least on my older models.

Plankton rise and fall at ends of days.
Some can cause a density so high it can interfere with your "picture".

Graph type I have not run. You may want to research clarity of what is depicted.
I can see stumps and bumps. But fish are all represented as facing the same direction..

Underwater cameras designed for fishing might interest you too for fine observation of interesting spots. A stationary perspective. Though twirling a cable can rotate a stationary camera.
Amazon product ASIN B00CJJ9WWM
 

I’ve notice some of these units hummingbird and others if used correctly you can see structures and old foundations in local lakes and rivers, if anyone currently uses these units for this can you please tell me the better units and features that discovered such great photos, videos thankyou
:lurk: never thought of that - nice divergency...
 

Look into "sidescan" capability.

In silty or marl type bottoms , bottomline/greyline(?) sensitivity adjustment capability can help. A unit without it you can for example , not notice fish hugging bottom.
Too great of sensitivity on everything can be self defeating though. That's why being able to adjust helps.

Electronic isolation of a unit helps. And some will sense other units nearby by interference. Some may have aftermarket or options for filters. Or different settings. You don't want to hear your motor fir instance. Or radio wired to same power source. At least on my older models.

Plankton rise and fall at ends of days.
Some can cause a density so high it can interfere with your "picture".

Graph type I have not run. You may want to research clarity of what is depicted.
I can see stumps and bumps. But fish are all represented as facing the same direction..

Underwater cameras designed for fishing might interest you too for fine observation of interesting spots. A stationary perspective. Though twirling a cable can rotate a stationary camera.
Amazon product ASIN B00CJJ9WWM
Maybe if you were already over a site of interest in the water, to confirm your location or get a better understanding of edges. Were you originally speaking about using a fish finder on land, or looking for POIs in the water, other than fish?
 

I’ve notice some of these units hummingbird and others if used correctly you can see structures and old foundations in local lakes and rivers, if anyone currently uses these units for this can you please tell me the better units and features that discovered such great photos, videos thankyou
I dont see why not.A fishing buddy here just bought a fantastic unit.It sees under the boat,forward the bow 100 Ft.
And side-scan Port & Star.But it cost $2,500 plus $1,500 for the transducer .
Also I ran into this guy a few years ago who is looking for the Town of Monroe (under SML lake)
>> https://www.waymarking.com/waymarks/WM7P2A_Old_Halesford_Bridge_Smith_Mountain_Lake_VA
 

Maybe if you were already over a site of interest in the water, to confirm your location or get a better understanding of edges. Were you originally speaking about using a fish finder on land, or looking for POIs in the water, other than fish?

Fish finder while on water underway.
Camera when focused on items/structure(s) / P.O.I's noted with fishfinder/sonar ( camera used while not underway.)
 

Yeah like I said, these units where made for fishing, but I noticed digging with 7, relics radio uses them to find old foundations in relatively shallow waters, and the view are great
 

My favorite fishing spots are small(ish) mountain lakes with limited access. I usually bring a Saturn Kaboat (a crossbreed of Zodiac and kayak) with a trolling motor to navigate them. With that kit, I use a Garmin sonar with SV technology, which "sees" both below and to the sides. If I notice something that looks like a foundation, well etc. on a sonar screen, I just grab a metal detector and go snorkeling.
 

Been watching the guys with the fish cams , they are very interesting , maby a coincidence but was thinking of ordering the cams for this same purpose. Sorry , did not mean to side step the thread.
 

Yes for metal detecting purposes, the rivers and lakes go down some during the year, nobody knows who lived where and when before maps came out, we really don’t have a clue, this is for certain anywhere there where rivers and lakes that’s where the Indians or early settlers lived, now a lot is under water and most don’t venture into that area to detect yeah so appreciate your time
 

I have a Raymarine Dragonfly 4 Pro ($300+/-) that I put on my kayak or sailboat and it is amazing what detail it shows of things like submerged trees and structures (a local reservior has an old bridge and road and LOTS of stumps under the current surface). The detail setting is "DownVision" and it just looks like a night-vision image of the structure. Also has a chart-plotter so I can mark spots with GPS.

Don't know that it would be much help metal detecting. The water has about two feet of visibility.

Here's a sample display (not mine):
 

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A fish finder (as far as I know ) is not a metal detector but.It will give you a good view of the bottom.Even with this 'cheap' model . A man made structure could easily be spotted.
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Yeah I understand it’s not a metal detector but I does shoe struct and stumps possibly early settlers structures that live by the rivers that became lakes today
 

I’ve notice some of these units hummingbird and others if used correctly you can see structures and old foundations in local lakes and rivers, if anyone currently uses these units for this can you please tell me the better units and features that discovered such great photos, videos thankyou
I use a Garmin Sonar/Chartplotter. The Sonar has Chirp technology. Look at it as a finder with multiple frequencies for fantastic detail compaired to a regular finder that usually runs on 2 freq.
I also have a Navagation Case which includes an IPad pared with a Garmin GLOll (gps) with GAIA mapping, Internet for Google Earth in real-time with mapping and aerial photos.
The resolution on the sonar is so good it’s sometimes looks like you are looking at a photograph. Only good to around 50-75’.
Pix are from searching for the remains of old RR bridge on St John River in Fl. Used the topos to follow the old RR bed, ran a grid pattern, found the piers and structure the whole way across the River!
One of my main tools in my treasure hunting arsenal.
 

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The drone comes in handy getting into overgrown areas. Run an aerial grid of the area before bushwacking in. Load the lon/lats in taking pix and video for features that would be overlooked or not seen at ground level.
 

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