Question for experienced detectorists about silver coin depths.

[Chefjuan]

Why a silver dollar? How many of us actually hunt and find those consistently... why not a quarter or dime which is what we find most often?



Just sayin, let's keep it grounded and real, no offense, but I couldn't resist challenging that statement as I hunt with guys with a deus and stock set ups, they aren't hitting 14-15 inch coins... now slap a 17 inch coil on there then you have a chance at coins of that depth, but consistently with great target ID like you said, not so much. lol

+1


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[calabash digger]

Hey thanks for calling me on it went to test garden and dug a hole 15 inch half no problem and a 14 inch barber quarter no problem with the 9 inch coil and it gave a high tone on both and the funny thing in real world hunting I would have dug both. Btw the guy who told me his test results I didnt question because I trust him and he is and old pro . The videos will be up tommorrow thanks for bashing me a little made me get off my lazy tale and practice what I preach. Man the Deus is a deep machine if you know how to set it up. I am keepin it real thats why I went and shot a video of the machine doing it.

 

[IDXMonster]

Well put Nectar. And we should be thankful things aren't as easy as we wish sometimes or there'd be nothing left to find! Whether I find stuff or not it's always a good time getting out to hunt.

 

[BottleCapKing]

How deep you can find a coin is predicated on several things (not exhaustive list)

1) The ground conditions (mineralization, acidity, moisture content, temperature of the ground at depth, etc)

2) How good of a ground balance you machine gets. All ground balances are not created equally. The ground balance on a Bounty Hunter is not going to be the same, or as good as the ground balance on a 3030. If your machine can't properly track the ground, it is going to muck with what your machine tells you. Good targets could sound bad. Bad targets could sound good.

3) The target itself - Conductivity, thickness, diameter, symmetry, and shape. Highly conductive targets produce a stronger induced response field (this decreases as frequency increases). A target with a large surface area will produce a stronger induced response field. A thick, highly conductive target with a wide surface area (like a silver dollar) will produce a much stronger response than a dime sized object made of the same material.

4) The position of the target in the ground. This is extremely important. If you find a 15" coin, you can bet that coin was lying as close to flat as can be. The more angled the coin, the less likely your detector is going to see it. It doesn't matter the machine you are using. All detectors are bound by the same math. If someone tells you they found a dime on edge at 12", they are either lying, or they picked up on something bigger, or shallower, and the dime was a secondary target the machine probably didn't even see. It doesn't matter what machine you are using - a deep coin on edge is for all intents and purposes - invisible.

How strong an induced field a target produces is based upon the flux passing through the surface area of the target. as the angle of a coin goes from flat (0 degrees) to on edge (90 degrees) you are progressing from maximum surface area to an absolute minimum surface area. The smaller the surface area, the weaker the induced field will be. The strength of a magnetic field is inversely proportional to distance (in this case, depth) the target is from the receive coil. At, say, 10 inches (25.4cm, 0.254m), the receive coil is trying to detect the response of a field that is effectively 61x weaker 10 inches away from the target. As a coin's angle increase, the field strength seen will be approximately cosine(coin angle)

5) Sweep speed. This is something that people tend to overlook. Most people I see have a really fast sweep speed. This is generally not good unless your detector has a really fast recovery delay. If you sweep too fast, your coil will be over and past a target before it finishes processing the signal, which will result in a clipped, masked, or entirely missed target. conversely, if you swing too slow, you are going to be seeing the same target multiple times. Faster swing speeds are generally better in highly mineralized ground, where as slower speeds work best in low mineral ground.

6) Swing consistency. You need to keep your coil on the ground. If you are U-arcing your swings, you only have a very small window in which your detector will detect its deepest (approximately 1 coil width). As you lift the coil away from the ground, it harder it is to detect an deep object. There is significant loss for every inch you raise your coil off the ground. (using the above example, bringing your coil 1 inch off the ground will turn that strength 1 signal to 0.76, 2 inches makes it 0.59, etc. This isn't much of an issue for shallow targets. It becomes a huge issue for deep targets.

7) Sweep direction. This is why many people grid. You could miss a target depending how you sweep across it. This isn't so much important for an approximately flat coin. It is symmetrical and will respond uniformly regardless of the direction you sweep across it. This changes as a coin's angle increases from flat to edge. The target is no longer symmetrical in all directions. It will sound different in one direction than it will in another. Those targets will also pinpoint with an offset either to the left, right, toe, or heal of the coil depending upon the angle of the coin and the direction you sweep. This is why it is important to pin point from two directions (it eliminates the pinpointing offset caused by the coin being at an angle). If you only pinpoint in one direction, you will be digging in the plug walls for your target. As you can imagine, the deeper the target, the more important this becomes.

8) How well you understand your detector. If you don't have a firm grasp on what your detector is telling you, you will have a real hard time finding the deep targets. If you run your detector too hot for a particular patch of ground, you are going to lose depth. You need to know when you are running too hot.

9) Your detector in general. Depth doesn't come from raw power. I can raise the output of my transmit coil from 10v to 30v. That is 3x the output. It doesn't get me 3x the depth. It may get me an inch or two depending upon the soil conditions. Depth comes from better coils and digital processing. If your coil doesn't have a good null, it is going to be noisy and will affect your depth. if your machine has average processing abilities, you are going to have a hard time pulling those very faint signals from everything the detector is processing. Skill can only take you so far. You could be a master using a low end detector. You could out hunt average or better than average users of better detectors. In the end, someone who is just as skilled as you are, using a high end detector is going to find things you do not.

 

[jonnied1]

Every detector on the market will be fooled.
As I said if you're low on time cherry pick as I said before detect how you feel to detect.

To answer your million dollar question that apparently everybody wants to see a deep silver coin will read iron no matter how expensive the machine is.

Oh and don't forget iron can read like a coin.

Therefore you dig it all for deep silver coins

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Hey, I take offence! I'm an old guy getting close to 66 years old and I search out and dig the "iron foil nickel range" signals. I like gold!
Just kidding, but I do go after those signals.

 

[porschephile]

Most silver in my area is 6 inches or deeper but there are many exceptions. Of course depth is not all about age. Most Barber dimes I have found are much shallower than Mercs or silver Rosies. I have wondered if this is because many Barber dimes are worn thin and dont have as much mass to sink them...
Additionally, I find many more Mercs than I do silver Rosies eventhough there were more Rosies minted. I think this may be because older detectors found the later silver Rosies in the 60-70s because they were shallow and could not detect deeper stuff?..

 

[calabash digger]

keeping it real!

heres a video of the deus hitting the 15 inch half will post the one of it hitting a 14 inch silver quarter in all about detectors. This is my deep relic program setting not some trumped up hot setting that you cant hunt with. It calls it silver by the tone at 15 inchs thanks for the challenge Nectar. NO MATTER WHAT BRAND OF DETECTOR YOU USE YOU HAVE TO ADMIT THATS PRETTY IMPRESSIVE WITH A 9 INCH COIL!

 

[calabash digger]

keeping it real XP Deus hitting a 14inch silver barber

sorry about the hi jack . People who comment on the deus about depth have either never used one or dont know how to set it up. Here it is hitting the 14 inch quarter with my deep relic program.

 

[Right Brain]

To the OP: if you're using a Garrett just get another brand, then you'll find answers to some of your questions.

 

[NectarDetector]

To the OP: if you're using a Garrett just get another brand, then you'll find answers to some of your questions.

ATP finds Silvers at repectable depths, all of mine with the ATPro were between 2 and 8 inches deep, but I also only have the 5x8 coil on mine or it would hit em deeper, but it's no slouch on silvers!

 

[Garbagepicker]

I'd like to get some opinions from those of you who are more experienced detectorists and have found a lot of older silver coins. Do you notice that generally, they tend to be a bit deeper than the more recent coins? I've only found 9 silvers so far but they do seem to have been several inches deeper (6-8 inches) than the majority of the clad I find in the same area (1-5 inches). I know there are exceptions where, for example, you might find an old Seated or Barber coin near the surface and a clad dime at 7 inches nearby, and I know there are many factors such as soil density, obstacles like rocks and roots, etc, but I'm talking in general. I see these Minelab users finding older silvers quite often and I've wondered if it's mostly because of the extra depth they're getting. In short, what percentage would you estimate are found deeper than 8 inches or so, where some detectors might pass right over them? Thanks.

I have often wondered the same and it's not just silver but any similarly shaped coins of similar mass being found shallow and others much deeper. A side from what brand of detector and discrimination rants there are many factors that come into play. One factor is how long a coin stays in circulation. It's not uncommon for me to find pennies or nickles and even the occasional silver quarter or dime in pocket change minted in the 60's . I just found a 1955 Jefferson today. Lets assume that a coin can circulate 50 years. If a 1960 penny was dropped in 1960 it has had 56 years to sink and be covered by leaf decay and grass clippings. If the same 1960 coin is dropped in 1980 with 20 years in circulation it has 36 years to sink and if the same coin was dropped in 2000 it would have 16 years to sink. I would suspect that the same coin dropped in the same spot would be found at different depths. If I dropped the 1955 Jefferson I found today and a detectorist finds it 5 years from now they are going to wonder why it's so shallow when 3 feet away a 1980 nickle is much deeper. Why do I find modern crushed Budwiser cans 10" deep on an old 1800's property that has never had any fill ? The true answer is here and explains all metal detectorist depth questions in a 30 second video. https://www.youtube.com/watch?v=NzlG28B-R8Y

 

[NCtoad]

How deep you can find a coin is predicated on several things (not exhaustive list)

1) The ground conditions (mineralization, acidity, moisture content, temperature of the ground at depth, etc)

2) How good of a ground balance you machine gets. All ground balances are not created equally. The ground balance on a Bounty Hunter is not going to be the same, or as good as the ground balance on a 3030. If your machine can't properly track the ground, it is going to muck with what your machine tells you. Good targets could sound bad. Bad targets could sound good.

3) The target itself - Conductivity, thickness, diameter, symmetry, and shape. Highly conductive targets produce a stronger induced response field (this decreases as frequency increases). A target with a large surface area will produce a stronger induced response field. A thick, highly conductive target with a wide surface area (like a silver dollar) will produce a much stronger response than a dime sized object made of the same material.

4) The position of the target in the ground. This is extremely important. If you find a 15" coin, you can bet that coin was lying as close to flat as can be. The more angled the coin, the less likely your detector is going to see it. It doesn't matter the machine you are using. All detectors are bound by the same math. If someone tells you they found a dime on edge at 12", they are either lying, or they picked up on something bigger, or shallower, and the dime was a secondary target the machine probably didn't even see. It doesn't matter what machine you are using - a deep coin on edge is for all intents and purposes - invisible.

How strong an induced field a target produces is based upon the flux passing through the surface area of the target. as the angle of a coin goes from flat (0 degrees) to on edge (90 degrees) you are progressing from maximum surface area to an absolute minimum surface area. The smaller the surface area, the weaker the induced field will be. The strength of a magnetic field is inversely proportional to distance (in this case, depth) the target is from the receive coil. At, say, 10 inches (25.4cm, 0.254m), the receive coil is trying to detect the response of a field that is effectively 61x weaker 10 inches away from the target. As a coin's angle increase, the field strength seen will be approximately cosine(coin angle)

5) Sweep speed. This is something that people tend to overlook. Most people I see have a really fast sweep speed. This is generally not good unless your detector has a really fast recovery delay. If you sweep too fast, your coil will be over and past a target before it finishes processing the signal, which will result in a clipped, masked, or entirely missed target. conversely, if you swing too slow, you are going to be seeing the same target multiple times. Faster swing speeds are generally better in highly mineralized ground, where as slower speeds work best in low mineral ground.

6) Swing consistency. You need to keep your coil on the ground. If you are U-arcing your swings, you only have a very small window in which your detector will detect its deepest (approximately 1 coil width). As you lift the coil away from the ground, it harder it is to detect an deep object. There is significant loss for every inch you raise your coil off the ground. (using the above example, bringing your coil 1 inch off the ground will turn that strength 1 signal to 0.76, 2 inches makes it 0.59, etc. This isn't much of an issue for shallow targets. It becomes a huge issue for deep targets.

7) Sweep direction. This is why many people grid. You could miss a target depending how you sweep across it. This isn't so much important for an approximately flat coin. It is symmetrical and will respond uniformly regardless of the direction you sweep across it. This changes as a coin's angle increases from flat to edge. The target is no longer symmetrical in all directions. It will sound different in one direction than it will in another. Those targets will also pinpoint with an offset either to the left, right, toe, or heal of the coil depending upon the angle of the coin and the direction you sweep. This is why it is important to pin point from two directions (it eliminates the pinpointing offset caused by the coin being at an angle). If you only pinpoint in one direction, you will be digging in the plug walls for your target. As you can imagine, the deeper the target, the more important this becomes.

8) How well you understand your detector. If you don't have a firm grasp on what your detector is telling you, you will have a real hard time finding the deep targets. If you run your detector too hot for a particular patch of ground, you are going to lose depth. You need to know when you are running too hot.

9) Your detector in general. Depth doesn't come from raw power. I can raise the output of my transmit coil from 10v to 30v. That is 3x the output. It doesn't get me 3x the depth. It may get me an inch or two depending upon the soil conditions. Depth comes from better coils and digital processing. If your coil doesn't have a good null, it is going to be noisy and will affect your depth. if your machine has average processing abilities, you are going to have a hard time pulling those very faint signals from everything the detector is processing. Skill can only take you so far. You could be a master using a low end detector. You could out hunt average or better than average users of better detectors. In the end, someone who is just as skilled as you are, using a high end detector is going to find things you do not.

Being a newbie, this is one of the most informative posts I've read! #6 was very interesting as I've been hunting in a park with very thick grass and can't get the coil closer than about 1.5-2" from the actual ground. Still found a bunch of clad, but most were in the 1-3" deep range. Thank you for the great post.

 

[Barracuda]

To the OP: if you're using a Garrett just get another brand, then you'll find answers to some of your questions.

 

[jbkelly3]

Soil conditions are everything ...... down here in the south there is a table top hard surface of red clay at around 6 inches in most places. Once you get to that, stop digging because nothing moves more than an inch in clay. Given that a decent (mid-grade) machine and time to learn it are the logical factors, and in that order! You can't learn to read through trash with a $50 machine ...... and a noob with the best out there will miss stuff others are able to find. Virgin (unsearched) ground is the best way to find silver ... but as rare as an honest politician.

 

[coin whisperer]

99% of the silver I find is less than 6" deep


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[calabash digger]

Ive never found silver over 8 inchs but knowing I can is a confident booster.

 

[BottleCapKing]

The biggest clue I normally have is that it repeats and repeats close to the same way at 90 degrees. If it's near stuff or there's potentially more things in the ground with it and it will only repeat from one axis THEN I will take the chance on it,if other things are nearby. Expecting a good and exact response from a deep coin,unless it's huge,is over-expecting...in my own experience.

A target that has a geometry that is consistent in all directions like a coin should sound the same from any direction when it is completely flat. Though, coins will sound different if their geometry changes (like they were clipped with a lawn mower, have a hole drilled in them, corroded, etc) when swept from different directions. The VDI difference may be big, it may be only a point or two. The less flat a coin lies in in the ground, the greater the chance it will ring up differently. A nickel lying at 45 degrees may ring up 19 in one direction and 17 in the other.

For targets that do not have consistent geometry from all angles (like pull tabs, pull rings, screws, nails, etc), they will have a much larger variation in VDI from one direction to another. (A coke can pull tab can be say 19 in one direction, but 37 in another). Wide variations like that give a good idea that the target is not disc shaped. But, then again, gaudy rings, bracelets, chains, earrings - things like that will probably have variations in VDIs from one direction to another too. People who actually find these things could better comment on this.

Multiple targets in close proximity poses another problem all together. If you can't separate the signals you will only see the one target. If it is a good target and it is the dominant target, the VDI you will see will be increased or decreased by what it is sharing real estate with. If your primary target is say, a nickel, if it is sitting on top of a penny, the VDI you see will be higher than that of a nickel. If it is sitting on top of foil, the VDI will be lower.

 

[Jason in Enid]

Alas, that didn't really tell me how it works. I will have to check the Minelab papers to see if they have something more ... technical. They usually have some nice papers written from a not-revealing-proprietary-information in regards to the science. Since I don't use a 3030, I am not interested so much in what it does from user perspective. I am more interested in HOW it does it.

I can see multiple targets with my V3i, though, I must say the PP aspect of the 3030 is pretty damn nifty. I wish my V had that! Being able to see multiple targets isn't quite the same as being able to PP those same targets all at once. I am kinda jealous.

Actually, the technology used in the CTX, E-Trac and a few other Minelabs is COMPLETELY different from every other detector on the market. It uses a spread of VLF signals and then it samples the return in the time domain, not the frequency domain. It's actually like a hybrid of VLF and PI.

 

[Jason in Enid]

99% of the silver I find is less than 6" deep


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Interesting. I would say that about 25% of my silver is from 4 - 6 inches, and 75% is 6 inches and deeper.

 

[coin whisperer]

Interesting. I would say that about 25% of my silver is from 4 - 6 inches, and 75% is 6 inches and deeper.

It's the rocky clay soil here I guess


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