What about Jewelry/ Ring "Sink Rate?"

Most of the coins (old era) that I wish to find.... are at depths of 11" - 27" here in sand-bar Florida.

Agreed. In the beach berm, where the soil matrix is well mixed and liquefied, and barring obstacles (pebbles, shells, rocks) or limestone hardpan, coins will sink via gravity and turbulent mixing to the point of near equal density (isodensity). On the beach this would be a very accelerated example of the basic principle that works inland - though the probability of encountering obstacles at depth is greater inland, hence slowing/halting descent to shallower depths. Still, all things being equal, an older coin under ideal inland soil composition will be deeper than a recently dropped coin (not so true for beach berm where coins sink rapidly).

Coins will sink rapidly at first due to the greater turbidity near the surface and a decidedly lower density matrix, but descent must slow with increasing depth (grains are more compacted.) Had Hernando de Soto accidentally dropped his newly minted 1539 Spanish gold coin on the Florida beach, it could easily be resting today on hardpan (clay or limestone) from 3 - 40 feet down, which is effectively at the earth's core for any MD. However, allow a storm surge to remove the lighter quartz silica and clays , and assuming the coin is not washed out to sea - there is a chance of recovery.

An objects' shape will affect sink rate: the more easily the object can displace the soil beneath it, the faster it can sink, all things being equal. Two objects of similar density, the object that presents less surface area will sink faster, though not necessarily true where turbidity is the major contributor. Turbulent mixing in the top layers of wet beach sand should move small objects downward at near identical rates (less frictional resistance would aid descent - a mini-ball has less resistance than a ring, and a ring may have less resistance than a coin and a coin less than a nail, and a nail less than a soda can ). On the beach, below the level of strong turbulent mixing the downward motion is primarily the effect of uneven densities (soil compaction vs. object density).

The expectation should be then to find newer objects at the depth of turbulent mixing at the shoreline. That is, within a few hours most small objects have mixed rapidly downward (assuming similar frictional resistance) and will slowly descend further over the ensuing month and years in the deeper percolated soil matrix until they reach their individual isodensity layer, barring an intermediate obstacle.

The oldest gold and silver coins exist under your feet but are out of reach to a MD. But more recently dropped clads on an active shoreline will have a higher detection rate, where the turbulent mixing is restricted to about 8 - 15 inches. Since beaches are volatile, storms can both mix coins downward and/or remove overburden to expose them. In the latter case wave action (and saltation via wind transport) will reestablish the sand overburden in short order again making them undetectable (plus any man-made sand deposition projects).

I bet the wooden nickel would last longer then a zinc penny!

Johnny,

Your vested time and intelligence are most welcomed here. Your observations/analyzations are accurate, candid and spot-on. Many of the things you report are in the beach DVD of the 2-pack DVD set. THANK YOU for your time-to-share!

Naturally heavier targets would sink deeper and ardent beach hunters know certain targets end up in certain areas after the tide rolls out but tides differ from day to day and tide to tide and when you take into consideration sands differ from beach to beach plain theory as whats where as no ryhme or reason where articles are found and depths etc.

I do know after a tide rolls out generally certain weight objects drop into a general distance from the tide line and if a target is found that you are looking for either a left or right turn and hunt the same general distance from the outgoing tide and similiar weight objects will also be found. Certainly a key and gold ring may be the same approximate weight and a clad dime and silver dime weighs the same so don't expect to find more gold rings in the same line or all silver dimes after finding one but try it and you will find your chances of finding a similiar targets greatly increase..

As far as land hunting an ardent detectorist just can spot old dirt areas from perhaps filled in areas to a degree and usually find one silver coin at 6 inches most other silver in the area will be approximately the same depth. Lots of theories abound as over the years have read many but the detectorist that knows his area and what unit to use for a particuliar area or for that matter what coil will get his share of goodies in the pouch. Theories are great on paper but in the field ???