By Terry Botts
From Page 31
April, 2002 issue of Lost Treasure

One well-kept secret of serious experienced relic hunters in the Virginia and Carolinas is the Nautilus line of metal detectors. The Nautilus line has for years been built by Tyndall Electronics, but recently changed their name to Nautilus Metal Detectors, Inc. Nautilus has a full line of metal detectors for the most demanding beach, coin, relic and gold hunter and offers a durable, dependable, high quality detector at an affordable price. One of the few companies where you can call and actually speak to the owners directly.


At first glance, the beginner may be somewhat intimidated by the Nautilus detectors knobs, buttons and switches. To be truthful some of the earlier models were a little complicated to operate at full potential. Nautilus, not to ignore customer feedback, has developed a very simple almost turn on and go professional quality metal detector, the DMC IIBa. Three decades and thousands of recoveries later, I was given the privilege to field test Nautilus Metal Detectors latest addition to their detector line, the DMC IIBa.

The DMC IIBa is essentially two separate detectors in one (All Metal and Discriminate operating at the same time) with four modes of operation.

1. Ground Reject (motion)/Discriminate (motion) - A continuous tone is heard in one earphone for all metal and a beep tone is heard in the other earphone for discrimination when the loop is passed over a target.

2. Ground Reject (non-motion)/Discriminate (motion) - Threshold will remain constant when the search loop is held over the target and discriminate will be a beep tone.

3. Discriminate (motion) - Low tone in both earphones that increases when loop is passed over the target.

4. Discriminate (non-motion) - Low tone in headphones constant when loop is held over target.

The control box has a variable power setting for mineralized soil conditions, automatic searchloop balance control button/switch, a discrimination level adjustment and threshold control to adjust tone level.

The DMC IIBa is an induction balance-type detector where the coils in the search loop are arranged to provide feedback for the metallic targets nearing the search loop. This feedback is processed by the control box electronics to provide an audio signal to the headphones. Depending on the selected mode of operation, the signal will give an increase in the threshold tone, a beep tone or both. Operating at preset values will provide the beginner with good operation; however, it is recommended that search loop and ground balance be performed for optimum performance.

The DMC IIBa is mounted on aluminum S-rod with a padded armrest. The control box is also aluminum. All control knobs and switches are of the highest quality and will offer years of trouble free operation. The four batteries are mounted on the back of the machine for easy access during in the field changes. Alkaline batteries are recommended and will provide about 15-20 hours of operation. Also, 8.4-volt rechargeable batteries can be used in conjunction with the convenient built in battery charger jack to provide recharging without removing the rechargeable batteries. Re-chargeable batteries offer about half the life of alkaline batteries. The DMC IIBa offers four different sized field interchangeable search loops, 6, 8, 10 and 15 inch.

The detector arrived well packaged with a 10-inch coil and a set of 8-ohm stereo/mono switchable independent volume control headphones. Only minor assembly was required before installing the four-volt alkaline batteries. Being familiar with other Nautilus detectors was a plus. After following the simple operating instructions I was up and detecting in just a few minutes. After a quick run over my test plot, I found the DMC IIBa easily located my deepest buried mini ball at 12 inches and gave a strong reading on a reproduction eagle cuff button at 8 inches. These items have been buried in hard, compacted sand/clay mixed soil for over eight years.

Field Use

In mid August all of my favorite relic sites were still in crops or overgrown with underbrush. I had a North Georgia vacation planned the last week of August, visiting relatives and the 125-plus-year-old mountain home place of my late father. When I was a young child, my father told me he had lost an 1835 penny in front of the cabin fireplace. He was playing with the coin and it fell through a crack in the cabin floor. Hoping it must still be there, I was attempting to recover it. The log cabin was torn down over 40 years ago with only portions of rock from the foundation remaining.

I have unsuccessfully detected there for five years with two other metal detectors. This in part is due to the fact that the red clay soil is highly mineralized and the site is littered with iron roof fragments and cut nails.

The Nautilus DMC IIBa ground balanced fine without the false signals I had experienced with the other detectors. I set the detector in the Ground reject/Discriminate mode and was able to pick out iron targets from good targets with the dual tone response. Iron read in one low tone with brass and copper in a higher beep tone. I was not successful in locating the 1835 penny. I did, however, find a childs belt buckle and half of a womans locket with a deer engraved on the top.

My next test trip would require me to wait several weeks for crops to be harvested. This site has been searched by every make of metal detector imaginable for over 20 years, yet still produces some valuable finds. It is the site of a Civil War battle that was a miserable defeat for the First District of Columbia cavalry during the Siege of Petersburg. The site is a good testing ground because the few remaining targets are usually deep, thus making the detector and its user be at their very best to find anything.

I arrived and completed the search loop and ground balance procedure. I set the detector in the Ground Reject/Discriminate mode. Discrimination set at 22 on the scale. The field had just been cut and was in perfect detecting condition.

The soil was very dry and hard, as we had not had any rain for several weeks. Making my way back to a favorite spot in the field, I easily detected four 22-caliber bullets and three buck shot pellets at depths of 3 to 5 inches. After about 45 minutes of not finding anything of value, I moved to another area in the field where I had found bullets on past trips. I wasnt there long when I got the dual tone reading in my headphones. Getting both tones simultaneously usually indicates a good target. At about 9 inches I pulled out a nice 69-caliber round ball.

The ice was broken now - I had finally detected a Civil War relic. In 2-1/2 hours I had found three Civil War bullets, four .22 caliber bullets, three pieces of buckshot and about a dozen brass shotgun shell bases. I was very satisfied with how well the DMC IIBa performed in a hunted out site.

The next test location was an early 1800's home site Dinwiddie, Virginia. It is a five-acre plus tobacco field with an ancient rock chimney standing in the middle of one end of the field. The field was disked to a depth of about 10 inches. The soil was very dry from the lack of rain and it was like walking on the moon. I sank down about 3 inches with every step. The dust was terrible, but digging was a cinch. With the Nautilus DMC IIBa coil, and ground balance set, I chose the Ground reject / Discriminate mode setting again.

Pieces of broken china and old cut nails littered the site. I recovered several small brass fasteners and the bolster to a pocketknife. Everything located was within 10 inches of the powdery soil except for a few large iron targets recovered several inches below the plow line. I could have used a beach scoop to make my recoveries.

About 25 feet from the fireplace I got a good dual tone reading. Taking care not to damage the target, I took an oversize scoop of soil leaving a hole about 6 inches deep. In the scoop of dirt I recovered a very nice 1800's vintage flat button with an enameled design in the front. Continuing my search, I recovered several old shotgun shell bases and pieces of aluminum drink cans. Not being hindered by the large number of small nails was a noticeable plus of the DMC IIBa discrimination circuit.

While detecting about 50 yards directly in front of the rock chimney I got a strong dual tone signal. I began removing 2-3 inches of soil at a time until the target was out. At about 8 inches the target was recovered in the small pile of soil beside the dig hole. Sifting through the powdery soil I got a glint of something gold and shiny. Low and behold I had found my very first gold coin. It was an 1855 US $1 gold piece! It is in great condition, although it has a small hole drilled in it.


The DMC IIBa may look complicated, but it is not. The setup is trouble free with the easy to understand instructions. The average person with little or no experience could easily set up this detector and be finding artifacts in a matter of minutes. Performance is exceptional and the durable components make for years of trouble free use. I found the Ground Reject (motion)/Discriminate (motion) mode to be my favorite setting, however, thats my personal choice.

Unfortunately, I did not receive the detector prior to my early August beach vacation and did not get to do any beach hunting with the DMC IIBa. One item on the negative side is the weight of the detector. It takes a strong person to swing the 10-inch coil for a long period of time; also, the shortest shaft setting it is a little long for a small child to use.

However, one could cut it down or have a shorter shaft special ordered with a smaller diameter coil. Whether you are a seasoned pro or a novice to the hobby, the DMC IIBa will provide you with excellent results and product satisfaction.

The exceptional depth and features of this machine make the DMC IIBa a smart buy at the recommended retail price of $800. Check with your local dealer for special sale pricing offered through out the year.

For additional information or a local dealer near you, contact Nautilus Metal Detectors Inc., 29 W. Lemon St., Coats, NC 27521, call 910-897-7950, or e-mail: digno2ataol [dot] com

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