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Friday, February 10, 2023

2/10/23 Report - Gold and Rare Whiskey Shipwreck. Metal Detecting Subtleties of a Saltwater Beach.

 

Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.



The ship was lost during a storm on 7 December 1854, taking with it 17 of its crew, gold, and 280 barrels of whiskey. It wasn’t until 2010 that it was rediscovered, in Platte Bay, Michigan, by diver and shipwreck hunter Ross Richardson almost 60 metres below the water’s surface using sonar to scan the lakebed. The cold water has kept the wreck in good condition, making it one of the best preserved wrecks from the 19th Century.

Now, Richardson is seeking a permit to salvage some of the treasure from the wreckage, a requirement for removing artefacts from the Great Lakes. Though he estimated that his quest for the wreck cost in the region of $10,000, what lies within could be worth significantly more than that. Inside the wreck is a large number of coins, likely the pay for the garrison on Mackinac Island, where the ship was headed on its fateful final voyage. Richardson estimated that the value of the coins was in the region of $20m...

Here is the link for more about that.

Rare whiskey could be salvaged from 170-year-old shipwreck (thedrinksbusiness.com)

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I first heard somebody mention it at least a decade ago.  A fellow was using a Minelab GPX metal detector at John Brooks. The detector was a high end metal detector that was commonly used for finding gold nuggets.  It cost over $5000.

Anyhow, the fellow told me when he swept his coil north/south he got better performance than when he swept east/west.   He told me he thought it had something to do with the earth's magnetic fields or something like that.  That was the first time I heard someone mention the difference between swinging north/south versus east/west, but it wasn't the last.  In fact, someone mentioned the same thing to me just yesterday.  I guess it is a common observation.

Obviously, water goes up onto the beach in waves.  At some point on the slope each wave stops. That creates a relatively sharp line between the newly salt water soaked and dry sand. 

Something similar can happen when you dig a hole in the beach. You create an abrupt change in ground mineralization, which can either cause a false signal and/or a loss of depth as your metal detector tries to adjust to the change in mineralization.

Metal detectors have to deal with changes in ground mineralization. They attempt to cancel it out, and they do that more effectively when the mineralization changes are less abrupt. 

Beyond the metal detector's attempt to deal with mineralization changes, the operator can take steps to adjust the detector to reduce the effect of ground mineralization. Depending upon the metal detector and the operator's preferences, the operator might ground balance the metal detector, decrease sensitivity or use discrimination for that purpose.  Some detectors will cancel out the salt mineralization fairly effectively, but you will still lose some depth in the process.  It can be more or less, depending upon the detector and how you use it.

 You can detect the lines where the waves stopped if you want to, but most people do not want to.  When you hear a slight false signal where the last wave stopped, you might look down and see where that happened.  It does not hurt to hear those changes in mineralization if you can tell the difference between those signals and good target signals.  It is possible in most cases.

If you want to maintain maximum depth, you might choose to hear some of the signals caused by that type of mineralization.  Over-adjusting to beach mineralization can needlessly result in more loss of depth than is necessary.  Some detectors will adjust fairly effectively on their own, and some operators will adjust their settings effectively, but it is easy to overdo it.

If you use an Minelab Excalibur in the wet sand and use motion or discrimination mode, you might notice falsing in the wet sand areas.  When using an Excalibur, which I did a lot in the past, I always used it in pinpoint mode.  When you do that you will hear signals from the saltwater mineralization, but you can learn to tell the difference between the sound of mineralization versus good signals. The human brain can process that information as well as, or in many cases better than, the metal detector.

One day I was using the Excalibur in the wet sand at John Brooks and there was another detectorist who was also using one.  He was staying a little higher on the beach.  He asked me what settings I was using and told me he had trouble with false signals in the wet sand.  I knew, as soon as he asked that he was using the motion or discrimination mode.  In fact, I figured as much when I saw him staying above the wetter sand. 

When working the wet sand, I actually prefer to hear some ground mineralization, especially when using detectors, such as the Excalibur or ATX.   You lose less depth.  

Detectorists and manufacturers alike, work hard to cancel out ground mineralization, but that is like listening to a singer and not hearing the music.  You miss a lot.   There is the blaring black sand that comes in like the brass section, and there are the more subtle contours and tones of the beach.  (You can hear good signals through the blaring black sand even though many people try to cancel it out.)  And if you don't over-cancel, you can hear the rhythmic changing tones as you sweep side to side and maybe pick up your coil a touch at the end of each sweep, and as you sweep up the hill into the less saturated sand or cross the lines where each wave stopped. There is information in all of that if you learn to listen and interpret it.

When you walk parallel to the water line, your coil will be sweeping over the lines of mineralization caused by the waves.  If on the other hand, you walk up and down the slope, you will be sweeping somewhat north/south, and your coil will be moving more with, rather than across those lines.  When you sweep with the lines rather than against them, your detector will not have to work so hard to cancel out the noise and you won't lose as much depth.  

I personally don't mind hearing some of what most detectorists consider to be noise.  When you learn to interpret a sound, it is no longer just noise. 

As I suggested above, some metal detectors will automatically cancel out more than others.  And the manufacturers try to give you what you want.  Most people don't want to hear the beach.  Sometimes I do.  

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The surf on the Treasure Coast will be decreasing for the nest few days, and today we'll have more south wind.

Good hunting,

Treasureguide@comcast.net