<font face="Verdana">I have been at this great hobby for over forty years now and have NEVER worn out a search coil or a coil cover.
In all this time have I seen a well used or abused coil or coil cover? Yes, most certainly! Especially in the 70's, and into the 80's, but there are simple reasons why.
In the very early days of detecting we used BFO's and, especially, conventional TR's. Both non-discriminating and discriminating models that operated on the basic Transmit/Receive principle. Those early models were very reactive to the effects of mineralization and the consequences of improper coil presentation. That is, if the coil was moved towards or away from the ground from the height at which it was tuned, you would either get a pronounced nulling or a false audio 'beep.'
It was absolutely manditory to operate with the tuning set while the coil maintained a very uniform relationship with the ground. Naturally, one way to maintin a uniform coil-to-ground relationship was to 'scrub' the coil right on the ground.
This scrubbing technique did keep the coil at the same distance from (or on) the ground, but it was obviously quite abbrasive on the coil (or coil cover) to have constant, direct contact with the ground.
After we had the first ground cancelling models developed for us, we were able to balance out the ground mineral such that we could raise or lower the coil, somewhat, from the ground w/o any annoying false responses and/or nulling effects.
However, as we learned more and more about the affect that the ground signal plays on a detector's performance, the more we realized that having a search coil's generated electromagnetic field too close or even in contact with the ground can actually impair the performance.
The answer to this? Operate with the search coil about 1" to perhaps 2" 'off the ground', which is possible because modern detectors almost all operate in a ground balanced condition.
A glance at almost any operator's manual will confirm that the manufacturer's tend to print the suggestion that their detector model be operated with the coil about 1" above the ground. Some manuals suggest up to a 2" coil operating height!
So, due to the fact that it is best to search with a coil that is held off the ground, there is not going to be any drag, or associated wear & tear! Also, no scuffing or wear damage to the coil's bottom!
I will tell you that I have some friends and/or acquaintences who have trashed a search coil or lower rod, or even their detector! They abuse the coil, which ought to be kept slightly off the ground surface, but they scrub the coil and use it to whack short, stiff weeds out of the way and scrub against sharp rocks far more than I ever would on grass! That's NOT what I call 'use.' It falls in the category of 'abuse!'
Are there times when I DO use a coil cover? Yes. I like to use a coil cover on any 4" coil or those up to 5
