Tesoro Electronics Sand Shark Metal Detector
By Andy Sabisch
From Page 25
July, 1999 issue of Lost Treasure

Tesoro Electronics has long had the reputation of a com-pany providing high-quality metal detectors at prices treasure hunters worldwide can afford. Founder Jack Gifford and now his son James have always been innovators finding new, unique and effective solutions to problems facing detectorists in the field. My favorite form of detecting is water hunting and when I heard that Tesoro had a new water unit, I looked forward to giving it a try.
The Sand Shark is a fully submersible metal detector that operates on the pulse induction principle. Pulse induction detectors have long been known for their exceptional ability to ignore even the most severe ground conditions and detect targets at depths greater than those typically achieved with a VLF-type detector. Tesoro entered the pulse detector field a few years ago with the PIranha. Not resting on their laurels, James Gifford and the staff at Tesoro listened to feedback from customers worldwide and began work on an improved pulse detector. After considerable design and testing, the Sand Shark was released.
The control housing is the familiar rugged case found on the other two water detectors in the Tesoro line. Time tested, the case has proven to be extremely durable and leakage problems are virtually unheard of. One of the first enhancements one notices is the new drop-in battery pack which makes replacing batteries a breeze.
The face plate of the Sand Shark has four knobs which control the detectors operation. On the lower left corner, is a four-position mode switch. The positions are OFF, VCO, F SET and NORMAL. The Sand Shark actually has two distinct search modes NORMAL and VCO. In the normal setting, it will respond in a typical fashion; i.e., as the coil approaches a target the audio signal will increase in volume until the center of the coil is directly over the target. In the VCO (voltage controlled oscillator) mode, the pitch and volume will increase. Depending on the users personal preferences either mode may make it easier to pinpoint targets which is why Tesoro made both available on the Sand Shark. The knob labeled THRESHOLD adjacent to the MODE switch serves three functions. First, it allows one to adjust the background threshold to a comfortable level depending on whether you are beach hunting, wading in the surf or diving with bubbles flowing past the headphones. Turning the knob fully counterclockwise activates the battery check circuitry. And, when the mode switch is in the F SET position, the knob is used to adjust the audio frequency heard through the headphones. Since each person has their own preferred tone, this feature will let you customize the detectors response to your liking. The VOLUME control is self-explanatory which leaves the PULSE WIDTH knob. This is another feature found on no other pulse detector. In the middle position, detection depth and battery life is optimized. As the knob is turned clockwise (towards MAX), a significant increase in detection depth is achieved at the expense of battery life. Wreck divers will find this feature to be especially useful as larger items buried just below the bottom are often preferred targets rather then detecting every little piece of metal in the area. The Sand Shark will allow one to ignore most of the unwanted targets and get additional battery life at the same time. The key to most of the Sand Sharks new features is the microprocessor that makes up the brains of the detector. Without adding to the size, weight or battery drain of the detector, Tesoros engineers were able to add the adjustable frequency, VCO search mode and the variable pulse width.
Battery life in the center position is between 15 and 25 hours with 8 AA batteries. While battery life does drop in the MAX setting, rechargeable batteries can be used with no adverse effect thereby eliminating the cost associated with frequently replacing battery packs.
Another feature unique to Tesoros water detectors is the ability to use interchangeable search coils. Four coils are available three round (7 inch, 8 inch and 10.5 inch) and a 10 X 5 inch elliptical with the 8-inch coming standard. Coil covers are available for all sizes and are recommended to protect the coil itself. Each coil comes with a waterproof, screw-in connector that fits firmly into the rear of the control housing. All of the coils use the Printed Spiral design which is another first for Tesoro. The Sand Sharks coils are actually a circular or elliptical printed circuit board encased in epoxy resin. This reduces false signals caused by bumping the coil against a hard object such as a rock, increases sensitivity to smaller targets with windings across the entire coil face and results in less drift from changes in coil temperature.
The metal shaft has also been improved upon. Now a three-piece assembly that locks firmly together, it breaks down quickly for easy storage or packing into a dive bag or suitcase. Also, with the center section removed, it is the ideal length for divers thereby eliminating the need to buy an additional conversion kit for that use.
Field Test
Shortly after receiving the unit I flew to Florida on business. Since I would be staying on the beach in the vicinity of where the 1715 Spanish Galleon fleet sank, I couldnt think of a better spot to test out the Sand Shark.
Walking out of the hotel I was somewhat surprised to see two other people swinging their detectors. But, realizing no one gets it all, I set the detector to the mid position on the PULSE WIDTH control and began hunting towards the surf line. Having hunted this area several times in the past with VLF detectors, I appreciated the pulse circuitry as I approached the wet sand. The threshold did not waiver in the least and I began to pick up several targets just above the where the waves were lapping. Armed only with a hand scoop, I could see I was at a disadvantage as several targets were beyond the point that I could recover them before the hole would fill back in. I did find several coins, at depths ranging from 6 inches to well over a foot in the wet sand. Im sure that had I had a long-handled scoop, I would have done quite well in the shallow water just off the beach. In a little more than an hour, I had recovered 23 coins and a hotel key from the wet sand area.
A few days later, I drove up the coast a few miles and tried my luck at a public beach that had more traffic than the hotel beach did. Again, as I got into the wet sand, I started finding keepers on a regular basis. I alternated between the 8-inch, 10.5 inch and elliptical coils to see how each performed in the wet sand/surf area. All produced rock-stable operation with no change in the threshold until a target was detected. This beach had a slight cut near the water line and nearly 25 coins along with a silver pendant and a small gold pinkie ring came out of an area less than 10 feet in diameter. The ring was quite dainty and was almost 6 inches down in the wet sand; however, even with the larger elliptical coil the Sand Shark produced a clear signal as the coil passed over it.
Even though it was an early weekday morning there were people all over laying on blankets in the sun. The 7-inch coil was the perfect size to get underneath the wooden steps crossing over the dunes, around some of the cabanas and near the unused wooden lounge chairs. Coins, keys and several nice Zippo lighters wound up in my pouch. Switching back to the 10-inch coil, I wandered down to the waters edge and again found numerous targets in the wet sand at depths ranging from just under the surface to nearly ten inches down. One of the last targets I found was a 14 kt gold chain with a gold religious medal. It had been a good eight inches down and sounded off with a clear signal a great way to end my trip to Florida and the Sand Shark field test!
If you are a treasure hunter looking for a versatile detector that is equally at home on the beach, in shallow water or diving on a wreck 100 feet below the surface, the new Sand Shark deserves your close attention. The unique search coil design provides superior sensitivity to smaller targets and better coverage with each sweep and having interchangeable coils allows one to select the optimal coil for a given application. Combine these features with the enhancements described above and you have a detector that offers a lot of value for the money.
The Sand Shark sells for $679 and comes with Tesoros limited lifetime warranty a feature found on no other water detector on the market. This shows just how confident the Tesoro staff is in the quality and durability of their products!
Call the factory at (800) 528-3352, write them at 715 White Spar Road, Prescott, AZ 86303 or visit their web site at for more information on the Sand Shark or to obtain a copy of their informative metal detector information booklet. Be sure to mention you read about the new Sand Shark in Lost Treasure!

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