Sure, I've hit targets at 20" as well, but certainly not with any routine and of the few I have hit at that depth most of these were fairly large targets, a silver quarter, a large silver mans ring, a 14k class ring, a 14k large old signet ring, etc. Of these, none of them came from water deeper then about knee deep and most of them came in Disc mode rather then PP mode. In CJC's book, "Advanced Field Methods" he even touches on how, and why, PP mode can be negatively effected as saltwater depth and motion is increased, often to the point where Disc is actually deeper and more efficient then PP. I've even run into this same thing up here in Indiana while hunting on land with the machine. So clearly the "PP is always deeper and more efficient" statement isn't accurate. As for the larger coil, and for these same general reasons, I've even seen times where I can clearly get more depth and efficiency out of the smaller coil because there is far less strata/matrix/mineralization being sampled, which in turn allows for greater sensitivity.
What has really become apparent to me since moving back to Indiana is just how much the strata and matrix and even the surrounding environment can effect machine performance, even seemingly insignificant conditions such as dense clay VS peat moss VS loose sand VS gravel, etc., etc. Seems I'm having to constantly keep my machine running in balance up here, which honestly, I would have thought would have been the other way around, the saltwater conditions in Florida being more of a problem.
