Getting More Depth From Your Metal Detector

By Dan Hughes, Associate Editor, Treasure Quest Magazine

Reprinted from TREASURE QUEST magazine, Summer 1993

Revised by the author, Summer 1998

It never fails. There's always somebody who is able to find more and better things with a metal detector than any other people who are using the same make and model machine. Why does this one person almost always do better than the rest of us? What are we missing?

Every metal detector has an absolute maximum depth that is determined by two basic factors: the diameter and physics of the search coil, and the electronic circuitry of the machine itself. In theory, it shouldn't matter who is running the machine.

But put any metal detector in the hands of a pro, and it will turn up deeper, older coins than when that same detector is used by a novice. What's the secret? How does the experienced treasure hunter find those deeper coins that you've been missing?

There are several simple rules anyone can follow to increase the depth of their metal detecting finds. The following tips will help you get the maximum depth, and therefore the maximum pleasure and value, from your metal detector. Follow these rules carefully, and in no time you'll be finding the deeper, older coins your treasure hunting buddies are passing right over!

1). Always use headphones.

And the best headphones to use are the big headphones with cups that surround your ears. They enable you to hear those weaker (and deeper!) signals that you miss when you use a Walkman-type headphone. A coiled headphone cord is much better than a limp, straight one, because like a telephone cord it doesn't get in your way while you're moving this way and that.

Depending on your detector and your own sense of hearing, there are two special features you may want in your headphones: a mono/stereo switch, and individual volume controls for each ear.

Some detectors require monaural headphones (Garrett and White's, for example), and some require stereo headphones (Tesoro and Fisher). Headphones with a mono/stereo switch can easily adapt to any brand of detector.

If you hear better out of one ear than the other, individual volume controls will let you hear the same relative volume in each ear.

Many people use headphones designed for listening to a stereo in an easy chair. These may be too fragile to last long when they face rough treatment in the field. Your metal detector dealer can steer you to a good sturdy pair of headphones especially designed for use by treasure hunters.

2). Slow down.

Most coinshooting beginners walk much too fast as they detect. It's hard to acquire the patience to slow down, but remember that the coins aren't going anywhere. (Especially not into your pocket if you fly right past them).

Slower detecting means you'll pick up deeper signals. But it is important to note that slowing down does not necessarily mean swinging your loop slower. To find the best swing speed for your detector, put a coin the ground. Swing your detector loop over the coin at different speeds, and raise and lower your loop to see what speed gives you the best depth.. Remember, it is possible to swing some detectors TOO slowly, so be sure to experiment with some coins on the ground.

3). Keep your loop low to the ground.

If you swing the loop an inch above the ground, you are costing yourself an inch of depth. And you probably paid quite a bit of money for that bottom inch!

Keep your coil against the ground as you swing it. (If you don't have a coil cover to protect your loop, get one). You'll hit rocks and scrape dirt when you keep your loop against the ground, but it is more than worth these minor aggravations to find the deeper, older coins.

4). Keep your swinging distance short.

The longer the length of your swing, the less control you have over your detector and the more you tend to lift the loop from the ground at the ends of the swing.

Not only that, but on those longer loop swings your loop makes more of an angle with the ground. And that robs you of depth. You should keep the loop absolutely parallel to the ground for the entire length of your swing, and move your whole arm without bending your wrist. (If your detector has an armrest, you won't be able to bend your wrist as you swing your machine).

5). Use minimum discrimination.

When you increase discrimination on most metal detectors, you lose depth and a lot of gold rings. I recommend that you discriminate out iron, but nothing else except when junk conditions are so bad you can't live with low discrimination.

If you must use higher discrimination, here are instructions on how to set your discriminator to eliminate pulltabs (this will cost you many gold rings): Put a pulltab on the ground and swing your coil back and forth over it, slowly increasing the discrimination until the sound of the pulltab breaks up or becomes erratic (or it may just go silent). Stop! You are now at a setting that will eliminate most junk, including pulltabs, but you will still find all coins except nickels.

There are some high-end detectors that have notch filters or target ID systems that allow you to skip pulltabs and still find nickels and some gold rings. Note I said SOME gold rings!

My first detector (in the early 1970's) was primitive, with no discrimination. I had no choice but to dig every bottle cap and pulltab in creation, hating every bit of it. BUT, I found more gold rings with that detector in the three years I used it than I have found in the last 20-odd years with a multitude of deeper, more modern detectors that have discrimination circuitry.

If you want to find gold rings, please go back and read that last paragraph again!

No, I'm not telling you to hit the flea markets in search of a primitive detector. I'm telling you to turn off the discrimination as often as you can stand it. Play this game: tell yourself that you are going to hunt with no discrimination until you have collected 25 pulltabs, or 50 pulltabs. By then you will probably be batty enough that you just have to turn the discrimination back on. At least this method gives you a fighting chance for some gold rings.

Remember, the other treasure hunters who use discrimination are skipping right over those gold rings. Those rings will not be found until some brave soul turns off that discrimination. Shouldn't that brave soul be you?

6). Overlap your swings more.

The deeper a coin is buried, the smaller the area of your detector's signal that reaches that coin. So in addition to the fact that your detector power is less on deeper coins, you also have a much greater chance of missing a deeper coin because your signal area shrinks as the signal goes deeper.

Think of the detecting pattern beneath your coil as a pointed-tip ice cream cone. Though your loop has a diameter of 8 inches, its detecting field narrows as the signal goes deeper, until at maximum depth your signal area is just a single point. Don't move that point too far with each sweep. The more you overlap your swings, the more likely you'll find those deep coins that you would otherwise miss.

7). Hunt when the ground is wet.

The wetter the ground, the more depth you're going to get from your detector. We all know we're more likely to get an electrical shock when we're standing in water. This is because water is a much better conductor of electricity than is air.

Similarly, your metal detector's signal can penetrate deeper into the ground when the soil is moist, and on a wet day you can find coins that are too deep to detect when the ground is dry. (Note: the ground can on rare occasions be too wet, causing false signals. If this happens, turn your sensitivity control down).

Besides better depth, there are two added bonuses of metal detecting after a good rain. The ground is much easier to dig when it is wet, and the root system of the grass is less likely to be damaged by your digging.

8). Practice as often as you can.

As in virtually every sport or skill, the more you practice the better you get. At first, it requires quite an effort to put all these suggestions into action. You must concentrate on each point, and constantly remind yourself to stay on track with each of the above tips.

But after several sessions, these difficult-to-remember procedures begin to become second nature to you, and you'll do them all automatically.

And that is when you'll find that you are the one who is leaving the others behind. When that happens, be a good sport and share these hints with them, too.