What's the difference between a double-D coil and a concentric one?

[china-clipper]

Ok, can someone explain the difference between and Excal Double-D coil and "regular" round concentric one like on a White's? How do they perform different? What "pattern" lies under the disc? How is pinpointing different? Etc?

Thanks, Rick

 

[Art (NWOH)]

DD coils have a somewhat rectangular shaped search field that extends the with of the coil from front to back. Somewhat like a book or box of cereal standing up. You get a lot of ground coverage even at max depth.

DD coils are generally accepted as better in bad ground.

Pinpointing can be done several ways...
X the target from two positions 90 degrees apart.
Work the coil foreward and back until the target is just at the front or back of the coil.
Work the coil foreward and back to see where the target drops off the front and back, then split the difference.

Concentrics have a fairly cone shaped pattern. Full coil width on surface targets and just a small spot on the deepest. Requires a lot of overlap in the sweep to get any coverage at depth.
Pinpointing can be done by X-ing the target while standing in one place to get the target centered up in the center of the coil.

H

 

[china-clipper]

OK, that makes sense, thanks. On the Excalibur (the 1000), what can be expected depth-wise for say a 14k wedding band? I mean general, say ... 6", 10", 12", etc? I have a White's PI and I can pull such a ring from about 12 -14" max. I was just wondering what an Excalibur would do.
Thanks again.

 

[Art (NWOH)]

I was afraid you would ask something like that...
How large and how heavy the ring is will have a lot of effect on this.
The particular area you hunt will have a great effect...high mineral or low mineral.

At this point it would help if you indicated the general area you plan to hunt so that some of the beach hunters in the crowd could chime in with info about what depth you could expect in your area with a Xcal 1000.

HH

 

[china-clipper]

Sure Art, sorry to be so ambiguous. I live in Connecticut and hunt mainly the salt-water beaches. I most likely will use the Excal in the water up to my chest and on the wet sand on occasion. I have my Surfmaster PI I use in the surf now and hunt dry and wet sand with my DFX. I seem to be digging a significant amount of iron and trash with my PI. My thoughts are to continue to use the PI for older, deeper targets such as jewelry in the winter months where there isn't much being replenished and the jewelry has worked itself down deep and is staying there. I thought of using the Excal during the "replenishement" (summer) season when the iron masking will make my hunting more efficient and I can cover more ground and dig more promising targets. I still love my PI as it does go deep.

 

[Art (NWOH)]

You will still get a little iron junk with an Xcal, but not much. Iron is always discriminated out unless it happens to be big enough or the right shape. Usually you can tell by the feel of it that it is iron.

Interesting that my Sovs (non-waterproof Xcals) and my Whites QXT both hit on the same kinds of iron and mostly reject the same kinds of iron.

You probably will not get quite the depth that you would with the PI, but you can skip most of the iron trash and get better ground coverage.

OK beach guys....get in here and tell Rick what he needs to expect on CT beaches....

HH

 

[ejudasf]

Art is correct about the slight loss of depth between a PI machine and the Excal.

Some people like to dig everything anyway, and that is good about PI units. Others don't like to dig iron or bobby-pins and that is where the Excal shines.

The depth issue can prolly be equalized by using a larger coil, like the S-12 or the 15-in WOT which also increases the search area per swing. This is great coverage. And don't be affraid of losing smaller items because of a larger coil, these coils can detect small targets.

 

[Rick(ND)]

For beach hunting the larger coil may be better, but in the water I think the bigger coils will be hard to swing. I had 2 differnt guys switch back to a smaller coil for water hunting as the big one were just to much to swing in water.