Detection Depth - Large Cache

[mredmond]

I suppose I should start by saying 'hi' as this is my first post...

Hi! I'm Matt from Dallas.

I haven't bought a detector yet and was hoping one of you folks could answer a question for me. I need to detect a fairly large cache of coins (primarily copper) that is buried about two feet deep. The cache consists of roughly one hundred pounds of metal.

Is this something most any detector would find? Or am I going to need something more $en$itive to find something that deep?

Thanks!!

 

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[Iron Patch]

Re: Detecton Depth - Large Cache

Most of the better brand named ones should have a good shot. You can easily test it, because if it will pick up a fresh buried similar target at two feet, one that's been in the ground a while will be no problem.

Do you have a good idea where it is, or is it a large area to search? A detector with a true all metal mode might be the way to go.

 

[Tuberale]

Re: Detecton Depth - Large Cache

Welcome to TNet, Matt!

You pose an interesting question. A single freshly-minted Wheatie weighs 3.11 grams. It would take 321.543 to make a kilogram, or 2.2 pounds. It would take 45.454 times that kilogram to weigh 100 pounds. So that 100 pound cache of copper coins would have almost $16,000 face value (in pennies).

I'd bet almost any detector would ring out on that cache at 2 feet. But just to be sure, when shopping for a detector, try to take a large copper skillet with you, and see how close to the coil the detector has to be to signal.

 

[mredmond]

Re: Detecton Depth - Large Cache

Do you have a good idea where it is, or is it a large area to search? A detector with a true all metal mode might be the way to go.

I'm reasonably sure I know where the cache is, at least the general area. I'll let you know after Christmas I will probably have to search about 10,000 square feet.

@Tuberale: Yes, it is a five-figure hoard.

Do you guys think the Garrett Ace 250 would get it done? I see others have recommended Tesoro but I can have an Ace 250 in my hands tonight from the store down the road.

...and thanks!

 

[gleaner1]

This is roughly a 12" x 12" square piece of copper that is 4" thick. Or 24" x 12" x 2" thick. At 24" deep, the 250 should work. 12 x 12 is a big hunk of metal. If the hoard was spread out in a box an area of 24" x 12", I am positive the 250 would find it. The bigger the spread, the better. This all assumes the hoard is in wood or copper or tin box, or ceramic jug/crock. If it is encased in rusty iron or steel, you might lose a touch of depth. But still, it mostly depends on the footprint size of the cache. A typical 11 x 7 x 5.5 steel ammo box will hold about 137 lbs of copper. Do air tests on hunks of steel and small appliances, microwaves, air conditioners, smaller steel things, about the size you think the cache is. If your machine picks these up at the depths you want, you will have the means to a happy ending. If your site is littered with big iron trash, like in an old homestead or farm, you will have a rough go at it. But do not give up. Good luck Matt.

 

[mredmond]

@gleaner1: Thanks for your reply! I went ahead and bought the Ace 250 and I'm going to go coin shooting today at the park to get the feel for it.

I laid an ammo box filled with about 30 pounds of ammo on its side and the thing dings pretty good from 18-24 inches away. Same with a fire hydrant and a car wheel. We'll see how it goes. I won't know until the week before Christmas.

Thanks again!

Matt

 

[Tom_in_CA]

While it's true that a standard detector (like an Ace 250, for instance) would pick up a target that big (as big as a hubcap or tool-box or whatever), you have to keep some issues in mind:

If your primary goal is to find that cached item, then your "standard detector" is also going to be sounding off on all the other stuff in the vicinity too. And no matter how much you tell yourself you'll "just ignore all the small signals" (tabs, individual coins, foil, nails, etc....) yet you'll spend all your time "checking just to be sure" (especially since you are new at this, and won't have an auditory frame of reference/experience).

One time I went searching through an entire block of 300 yr. old ruins in Mexico, with a standard machine (a Whites Eagle at that time) looking for caches. I reasoned the same thing: I don't need a 2-box machine, because a standard machine is "just as sensitive" to get box-sized items down to respectable depths, afterall. But what I found was, that I ended up chasing lots of can-sized cr*p, and spending all my time trying to guage depth vs size, etc... Because you see, a box at 2 ft, might have the same signal as a crushed can at 2 inches (if you're not accustomed to sounds, and trust me, even if you are, you'll end up checking "just to be sure").

Contrast to a 2-box unit, where it simply DOES NOT SEE/HEAR anything smaller than a soda can. So a 2-box machine sort of acts as the perfect discriminator against those pesky smaller items (coins, tabs, foil, nails, etc...) and you're not bothered all day with having to second guess small vs large (if, in fact, you strictly want your box, and not other stuff in the area).

And as a newbie, you may be thinking: "but the 10k square foot lot is clean w/no junk, etc..." Trust those of us who've done this for many years: unless your spot is out in the virgin wilderness, it will have a variety of nicknacks, trash, etc.... Even a simple municipal city yard, of a house built only in the 1950s, can have 100 targets in it, if you started getting a machine that is squirelly sensitive.

So you see therefore, your need, for your task at hand, is not for MORE sensitivity, but rather, for less sensitivity. This is why the machines of the 1950s and '60s found lots more caches than people do nowadays. Because by their very nature, they were lousy on coin-sized small itms, yet saw a tool box sized item "just fine"

 

[Keppy]

The problem with a 250 is it has no true all metal mode..& Yes a 2 box is the better detector ...As Tom_in_ca said you will dig a lot less junk with a 2 box......

 

[Tom_in_CA]

mredmond, you posted your post that you already bought a 250, before I hit the "post" button to what I wrote. Oh well. Go ahead and take it out for casual coin-shooting park-type hunting, as long as you got it, so you get the feel for the sounds, controls, etc... But as I say, this will actually work against your stated goal of finding the big item, and distinctly/specifically want/need to pass the smaller items. Not that it can't be done (if you dig *enough* holes, blah blah), but ....... I'm just sayin' ....... :P

 

[calisdad]

Tom couldn't he turn the sensitivity all the way down and perhaps scan the whole area without digging anything but marking targets with those landscapers layout flags? Knowing his target is copper he could notch everything else out (and leave the gold rings for someone else) . Once he had surveyed the area then he could decide on what to dig or not. Just a thought.

question: is an air test going to ring the same as something in the ground? the earth doesn't provide resistance?

 

[mredmond]

mredmond, you posted your post that you already bought a 250, before I hit the "post" button to what I wrote. Oh well. Go ahead and take it out for casual coin-shooting park-type hunting, as long as you got it, so you get the feel for the sounds, controls, etc... But as I say, this will actually work against your stated goal of finding the big item, and distinctly/specifically want/need to pass the smaller items. Not that it can't be done (if you dig *enough* holes, blah blah), but ....... I'm just sayin' ....... :P

Thanks for your input!

It can go back. I bought it at Fry's and they have a liberal return policy.

I guess I need to read up on these two box detectors. I know very little...

 

[mredmond]

(and leave the gold rings for someone else) .

Yeah. I'd hate for those pesky gold rings to interfere with my treasure hunt!!

So are you guys suggesting something like the http://www.kellycodetectors.com/garrett/garrett-gti2500pro_th.htm"]Garrett GTI 2500 w/ Eagle Eye Treasure Hound[/url]?

Geez that's a bit expensive - hope I'm right about where the cache is... Garrett is local to me. I wonder if they have a demo or refurb they'd let me rent for a couple weeks...

 

[gleaner1]

treasure hound or two box is really the only way to go. I just hit some sites, tried to find some used ones.....no luck. Try the dealers, they may have a used one. You probably could get most of your money back no matter what you buy. I would love to see you find that cache.

 

[Randyd]

if you know the size of the container, maybe you could use a probe before you dig and by pass the small stuff.
R

 

[bootyhoundpa]

what ever detector you use also keep in mind that something that massive might give an overload signal or a silent null.. the steel probe idea randy mentioned could sure save alot of time and digging..good luck...

 

[stevemc]

The better machine for that would be any PI, pulse induction, and a larger coil would be best. I use 2 different White's Surfmaster PIs, and they will find a beer can at 2 feet, and anything bigger at greater depths. I have dug up an anchor about 18" long at 3 1/2 to 4 feet deep. And in mineralized soils it will excel, and go deeper than any VLF, 2 box or otherwise, since it uses the conductivity to actually go deeper. That is why they are the best for saltwater and salt sands. Minelab started making theirs for the iron rich soils of the gold fields in Australia. I have a large coil (5' x 3') PI that will go very deep, but it will pick up a beer can at 6 feet in air and deeper if buried for a long time, or in water. Plus PIs are just turn on and go, no fidgeting, and you can turn down the pulse rate so that you can only find larger things. Or at least wont find real tiny things, and gold rings down deep.

 

[goverton]

mredmond, you posted your post that you already bought a 250, before I hit the "post" button to what I wrote. Oh well. Go ahead and take it out for casual coin-shooting park-type hunting, as long as you got it, so you get the feel for the sounds, controls, etc... But as I say, this will actually work against your stated goal of finding the big item, and distinctly/specifically want/need to pass the smaller items. Not that it can't be done (if you dig *enough* holes, blah blah), but ....... I'm just sayin' ....... :P

Thanks for your input!

It can go back. I bought it at Fry's and they have a liberal return policy.

I guess I need to read up on these two box detectors. I know very little...

Whites TM808 is exc. 2 box unit, easy to carry. Will pick up big items.
Do a search on ebay for "Whites TM606" none right now
Do a search on google for ad.
http://nevadanuggethunters.myfreeforum.org/archive/white-s-tm-808-for-sale-or-trade__o_t__t_311.html
http://treasureworks.com/forums/82-for-sale/1770-for-sale-whites-tm-808
http://elpaso.es.craigslist.org/spo/2639215977.html


IF all else fails, you might find someone in Dallas, Tx to rent you one(2box unit) Call around dealers selling metal detectors.

 

[Frankn]

Here's your answer! The guys that said 2Box unit got it right. Here's why. The 2Box will go down 12' easily for that volume of coins, and at the same time it will ignore the smaller junk. It will also cover a larger foot print on each pass. Buy a used 2Box here or on E Bay. Hays, Whites, Discovery & Gemini are among the best. Frank

 

[Tom_in_CA]

carlisdad, to answer your question: I too thought the same thing: "why buy a 2-box detector, when most standard machines will also easily pick up a tool-box sized item at a good 2 or 3 ft. anyhow?". And I too though the same thing: "It's easy, I'll just turn down my sens. and ignore all small sounding targets". But trust me: when you get out in to a hunt site, particularly if it's riddled with common trash (like where old ruins are, burned down house, etc....) you will spend all your time, no matter how hard you try, trying to discern small vs large. Because even with the sens. turned way low on the Ace 250, you will still pick up individual coins (albeit perhaps only 4" deep, vs 7" deep, or whatever had you been at full sens).

Sure, anything's possible. But just saying that realistically, no matter how hard you try, you will always be digging small stuff, worried that the "small thing" might actually be a "big thing" that was just so deep, that the signal itself was "small", on account of the depth. Example: You know how a soda can at 14" might sound like a quarter at 2", right? The same concept goes for a tool box at 2 or 3 ft, might sound like a can at 6", or whatever, to un-initiated ears. Especially for machines like the Ace 250, where there is no VCO type mode (ie.: it's just a "beep" or "no beep" machine, with little tell-tale audio to size out things)

 

[mredmond]

Here's your answer! The guys that said 2Box unit got it right. Here's why. The 2Box will go down 12' easily for that volume of coins, and at the same time it will ignore the smaller junk. It will also cover a larger foot print on each pass. Buy a used 2Box here or on E Bay. Hays, Whites, Discovery & Gemini are among the best. Frank

Alright guys, I just committed to buy a Garrett GTI-2500 w/ 9 and 12" coils plus a Treasure Hound. Used in very good condition for $700 which seems reasonable. I should be able to sell it if I want without much loss - but to be honest may end up keeping it.

I chose this because it was available and should get the job done.

Thanks again to everyone for the help.

BTW, a helpful hint if you don't already know how to do this... If you want to search *all* of craigslist at once, go to Google and search like this:

site:craigslist.org "Treasure Hound"

I know there are sites that try to do this, but they seem to get shut down as often as they pop up. This always works.