SCUBA Danger - Seriously Tanked

 Treasure diving had always held my fascination since I was a kid. Mike Nelson and his flaming magnesium underwater torch was the coolest; finding treasure, beautiful women, and still fight the bad guys deep in the depths! Luckily, my father was an avid diver, making his own gear before most of it was available commercially. Made his own wetsuit, bought a dual-tank set-up and he was off. I made the mistake once, during elementary school, when we were planning a bring your father to class event, of telling them my father was a scuba diver. This was like in 1960, when diving was not all that common. 

When Dad brought his tanks and gear in the day of our class, unknown to me, the subject was so interesting the teachers at the entire school got together and made it an all-school event in the school auditorium! Dad was expecting a short talk in a 20-student classroom, but instead found himself staring down a 650 sized student body, along with 20 or 30 teachers! I can still remember him, in his blue business suit, hefting the tanks on his back and the mask on his face while he explained in detail the use of all the gear. You would have thought he was a celebrated astronaut, and this was before astronauts! Afterward he was surrounded by interested teachers asking further questions. 

I thought he was going to kill me when I got home, and I was ready to explain that I had no idea they were going to do that, but he was still basking in the adulation of the 650-plus audience, so I escaped wrath of any kind. I was also the one tasked with bringing over 650 "thank you" notes home for him to read. One was mine. It read "Thanks Dad!" which my teacher chewed me out about, saying I showed no creativity in the note. I listened to all this and thought "Jeez, I see him every day, and I am still apologizing for what you and your ilk did without my knowledge!" 

Dad ended up teaching me to dive and also enrolled me in a NAUI scuba class at 14. I finally got my dive card, but not until NAUI had tortured me a few times diving in zero visibility water, tasked to navigate underwater with a compass, and how to change tanks underwater, or remove them completely. That last maneuver actually saved my life once, while I was doing an underwater hull-cleaning on a large yacht parked up against a seawall. 

I had gone under the boat and come up on the seawall side. I started cleaning the hull and was not particularly being very observant, when I suddenly noticed the tide was going out and the boat was settling on me. There was a slight concrete lip at the bottom of the seawall, not very wide, but my escape was blocked by this, and the curve of the hull was closing my escape upward to the surface. There was a large post at either end, near the bow and the stern so I could not get out that way. My tanks would never fit, and neither would I with or without the tanks! I suddenly realized I was going to drown.

trapped underwater in a confined space

 

My route back down under the boat was just barely wide enough for me to get through without the tanks. To make matters worse, passing boat traffic was making the hull ride up and down, creating sort of a continuous guillotine effect between the hull and concrete ledge. I'd have to time this well or be cut in half by a 25-ton boat! Either drown or be crushed. In the confined area I was in, I still managed to remember my NAUI training, and get the tanks and BC off, still breathing off the regulator. I braced my flippered feet against the seawall behind me, watched the hull coming up past the ledge, held my breath and PUSHED! I shot down between the yacht and the ledge and seemingly forever, surfaced on the other side.

My other buddies who had been working on the other side were astounded when I told them what had happened. I later showed them what had turned out to be a confined space, that none of us had recognized as such. You couldn't even call for help, because you could not surface by that time. Once again science, technology, training, keeping a cool head and working the problem saved me from certain death. Probably in a parallel universe I wasn't that lucky.

Pinpointing Targets - The million-mile stare

 One of the most difficult skills to master in metal detecting is accurately targeting signals under the coil. Some of this is due more to the lousy targeting abilities of less costly detectors, than the operator, Now, with small, handheld pulse detectors, many just assume digging a 12" wide, pizza-sized hole will suffice. Then waving the small electronic magic wand over the area, it will quickly and easily locate the target. We quickly remove and marvel at the gold coin we just pinpointed, then head for home. It's Miller time! No, sorry, just no. 

Pinpointing a target with a VLF metal detector is dependent on two things, well really one thing, the search coil, but in two flavors; concentric or the wide-scan (also known as a double-D) coil. When you find a likely target you would like to dig, with a concentric coil, you swing the coil back and forth above the target until the signal is either the loudest or the highest tone, or both, the detected target location will usually be, visually, at the center of the concentric coil. Usually I look for an item at the target point under the coil...a leaf, a small stone, twig...and stare at it as you swing the coil away ("The Million-Mile Stare") and you prepare to dig. When I first started out detecting, my technique after locating the target center in the concentric coil, I would do "the-million-mile-stare" at that location, swing the coil away, and push a coin-probe in the target center. It worked well as a visual-aid when digging, until I got the technique down pat. 

concentric target center on the left is usually where the red x is indicated
wide-scan (double-d) target center in green X is punching the "pinpoint control
Wide-scan (double-d) target locations red X front and back using "wiggle" method

You will find more expensive detectors will come with a wide-scan or "double-d" coil that pinpoints somewhat differently, When I switched from a concentric coil to a wide-scan coil, I found it somewhat difficult to pinpoint very well with the double-d, and had a few choice words with the %$#!&%$!& thing while out hunting the beach!  Metal detector manufacturers, thanks to computerization, have electronically "forced" the circuits to simulate a pinpointed target physically at the center of the double-d coil. And there is nothing wrong with this, as machines using the double-d coil get more technically advanced, pinpointing gets more accurate. BUT, and its a big BUT, understanding and using this coil to best advantage means using it as it was designed. I don't want to launch into another explanation on coils and how they work, just how they pin-point.

The solid strip down the center of the coil is called "the hot-shoe" on a double-d. When you are pinpointing a target, you don't have to use (although you can) the "pinpoint" button, but use a technique called the "wiggle" method. Upon gaining a target, in any mode you choose, you narrowly wiggle the coil back and forth while moving forward slowly, maintaining the target signal. When the target signal suddenly drops off, the target is directly behind the back edge of the coil. And this ability is what make water hunting possible with this type coil. Hunting in chest-deep muddy water? Can't see the coil? Use this technique, and once target is pinpointed, put your toe touching the back of the coil, swing the coil away, then move your toe back a few inches, put the long-handled beach scoop at a 45 degree angle just in front of your toe and dig, Chances are good you will dig the target on the first try, and you never even saw the bottom, you did it all by practice and feel. Don't try this with a concentric coil, though.

Another method in detector pinpointing techniques, using either type coil, is called "de-tuning," which increases the physical accuracy of the coil. As you swing over the target, as soon as you swing slightly away from the target center, punch the pinpoint button off and then punch it back on, and keep swinging, narrowing your sweep each time you de-tune. It takes some practice, but you will be making surgical recoveries of targets as your skills improve.

Still another technique we used back in the day, before electronic hand-held pinpointing devices were available, and still useful today if you cannot yet afford a pin-pointer, we called poor man's pinpointing. The fact was we were not poor, we were just underequipped. You managed to isolate the target using the detector's pinpointing feature, but the target is small, and hard to see or feel in dirt of the hole you dug, especially if you were wearing gloves. Frustrating though it is, the fact that a search coil, no matter what the type, will detect on both sides of the coil saves the day! Grab a handful of dirt from the dig and wave it over the top of your search coil until one handful sounds off, then poke carefully through the dirt in your palm until the target is located. It's Miller Time!

The really important aspect of all this, to you, and the hobby in general, is to master pinpointing, so you can excavate detected targets with surgical precision, and leave the 12" wide digs to the prairie dogs, keeping our hobby safe for coming generations.