Info I have on my Nautilus DMC-IIB says the coils are not waterproof?! Wonder if there's away to add waterproofing?
Air tests: Using the 6" coil, I get 8" with zincs rejected, 8.5" with tabs rejected, with ground balance set to 65 for average ground. With ground balance set to zero for unmineralized FL beach sand, that increases to 10". With GB set to 100 to mimic the worst dirt on earth only 1" or so disc & 3" all metal.
If I use the 10" coil. it adds another 2 or 3 inches, at GB 65.
Planted coin test: dime down 5"+ & somewhat tilted: solid pretty strong beep. Detector very stable. When noise increased inside house, I had to turn down sens from 9 to 7, but got "depth" back by increasing transmit power. The detector is 4 lb 14 oz including 4 9V batteries. It can work many hours using the heavy duty batteries that may still be available at a few places like Walgreens?
The mixed mode can be all metal in 1 ear & disc in other, or both modes in both ears. Then there's the non-motion disc if low mineralization can be found.
If you don't need a meter, a fun detector. If the weight is a problem, one can always invest another $37.95 for a Swingy Thingy. Best wishes, George (MN)