Written by the TreasureGuide for the exclusive use o treasurebeachesreport.blogspot.com.
 |
| Source: nhc.noaa.gov |
Here is one to watch. The one nearest to us will likely strengthen and could become a tropical storm in the next day or two. I'll be keeping an eye on that one.
--
Detectorists often talk of gridding. I take that to mean that they thoroughly and systematically covered an entire area inch by inch, not leaving any part of that area uncovered. Sometimes they don't mean it that way. Sometimes they mean what I would only call a lose grid, which may not cover every inch but still employs an up and down and back and forth pattern.
Above you see what I would call a grid pattern. The detectorist would start at bottom right and work bottom to top sweeping the coil right to left and left to right up the first column and then moving over and coming back down the next column, repeating that until the entire area of interest has been covered.
If you have a ten inch double-d coil, each step you take before changing the direction of your sweep should be ten inches or less, otherwise you would be skipping some area in your grid.
When I'm not worried about covering every inch, such as when I am just sampling an area, I might call that a lose grid. When I do that, I'm OK with missing a little. I'm just scanning an area to see how promising it might be.
The illustration above is unrealistic in several respects. First, it would be very difficult to make such perfect straight passes with a metal detector coil. That would be quite unnatural and would require you to move very slowly, deliberately and unnaturally. The natural swing would be an arc - not a straight line.
The illustration immediately above is not totally accurate either, but shows what would be a more typical arc-shape coverage pattern. The red arrows point to some of the ground that is not covered by the detector coil. If you walk faster and sweep while moving, you'll miss more ground. It takes a lot of discipline to not miss skip any ground.
It can be surprising to learn how much ground you are missing. I recommend throwing a target or two over your shoulder and then turn around and detect without looking at the ground. You might be surprised by how often you miss an easy surface target. I've demonstrated that to myself on multiple occasions over the years.
In actual practice, if you are holding your metal detector with your right hand, the arc would be tilted more to your right side.
The primary pivot point for the arc of your coil sweep would probably be your shoulder. Often your elbow will be another pivot point, and also your waist.
If you consider how you actually swing your detector, you would not be walking down the middle of the path covered by your coil because the more of the arc would be to your right if you are holding the coil in your right hand.
The following illustration shows how your sweeps will be more to the right if you are holding your detector in your right hand. To cover the entire area well, the distance between your north and south paths will not all be equal. The first north and south paths are farther apart than the first south and second north path because the sweep is longer on the right of the detectorist.
 |
| Path Adjusted For More Complete Coverage Without Much Overlap |
Here is an rough illustration of what I would consider a fairly normal sweep.
Note how much more of the sweep is to the side of the hand and the greater length of the sweep on the right partly due to the north to south movement of the coil as well as the east west movement. That can be used to advantage when are walking parallel to a cut.
Of course different people will have a different sweep and may vary their sweep at different times. I find it useful to be aware of how I am sweeping and will change it for different situations.
By paying attention to the biomechanics, you might be able to hunt tighter, longer, without becoming tired so soon, and [prevent overuse injuries.
There is also the matter of the vertical movement of the coil, which is just as important. It is not uncommon for people to lift the coil at the end of sweeps. That can cause more false signals and reduce depth to the extent that targets are missed.
The type of sweep you use is up to you and might change with the situation, but I think it helps to be aware of your sweep pattern. You might want to take your detector out to the beach and sweep it on the dry sand just to see the pattern you make.
I'm sure nothing I said today is very surprising, but it is one thing to know something and another to apply it. I have to remind myself once in a while.
--
Terry asked me if that wasn't a Mexico style cross on the reale I posted the other day. I took another look, and it does seem to be the Mexican cross. I thought it might be a Potosi reale before taking a closer look.
Thanks Terry T.
---
Keep watching the Atlantic.
Happy hunting,
TreasureGuide@comcast.net
