Friday, April 17, 2015

4/17/15 Report - Most Popular Posts. Marginal Signals. Detector Adjustments & Sensitivity. Shipwreck Gold Nugget.

Written by the TreasureGuide for the exclusive use of

Ancient Gold Pendant
Found With Metal Detector.
You probably noticed that I made a change to the first page of the blog.  It now displays eight of the most popular posts of the past.

I think this is a great feature because there are six or seven years of posts now, and that can be overwhelming.  This provides a good new way to see if there is anything you missed or simply want to revisit.

The post about this gold pendant is one of those popular posts.  It is listed at the top of the list.

Last night I stumbled upon an old post reporting on the find of a gold nugget on a Treasure Coast shipwreck treasure beach last year about this time of year.  That particular post didn't make the top eight list.   See the 3/17/14 post for that and more on gold nuggets.



Back a few days ago I talked briefly about rounding your curves on your sweep pattern as shown in the illustration below.  In wet sand an abrupt change in direction at the end of each sweep can cause false signals at the end of the sweeps.  This especially occurs when the change in direction occurs where a recent wave stopped and left a line dividing wet sand from dry sand.  If you have your discrimination up or your sensitivity low, you won't hear those transitions, but there can be a cost to that.

An increase in noise near the end of sweeps can cause you to miss what I have called marginal signals, which also frequently occur near the end of the sweeps.  Marginal signals can sound a lot like the noise caused by the coil passing over the line between the wet and dry sand.  Ignoring marginal signals can result in a significant reduction in finds. It can be difficult to distinguish between noise and marginal signals, but double checking will do the job.  When you sweep in both directions over the questionable signal, signals that remain consistent will be good signals.

Adjusting your detector to avoid all false signals can cause a loss in sensitivity that will cause you to miss good but borderline targets that are either small or deep.  Experience can help you distinguish between noise and marginal signals.  Double checking some of those hard to distinguish signals is always a good idea.

It is also a good idea to sweep your coil parallel to the water instead of East/West or towards and away from the water's edge.  That way your detector will not have to adapt to the changes in moisture levels and mineralization on each swing.  That will give you more depth, and if you are running hot, fewer false signals.

If you run your detector hot in all-metals or pinpoint mode, you can hear all of the changes in the moisture and salt levels etc., but you can learn to distinguish those sounds from real targets.  The same goes for black sand.

Many people feel like their detector doesn't work over black sand.  They hear the black sand and give up.  In an all-metals mode you definitely can hear the black sand, but you can also hear many of the targets in or under the black sand.  

An edge in the black sand, made by a scoop or foot print or something, can cause a signal that can be difficult to distinguish from a signal caused by a good target.

It is a good idea to work in different areas of the beach (dry sand, wet sand, and in the water) one at a time instead of making your detector adjust as you go back and forth from one to another.  With some detectors, you will want to ground balance again if and when you go from one of those areas to the next.

One time a fellow using a high-end Minelab gold detector told me that when he was sweeping North/South along the water he could detect targets deeper than when he swung perpendicular to the water.   He said he thought it had to do with the earth's magnetic fields.  He was a very bright fellow, but what he was really observing was the loss in sensitivity caused by his detector trying to adjust to the rapid changes in moisture and salt when sweeping East/West.


On the Treasure Coast today the surf is a touch higher.  We are having some good negative low tides though. 

Happy hunting,