I too would recommend Clives (CJC) book on the DF. CJC has many good tips in his books.
Thanks for the feedback all that is some good (I am sure hard-earned) advice. I am looking to get the book from Clive soon. In the meantime I will try the double beep thing. I was amazed at the depth it gets. I like the idea for indexing the knob for easier access underwater. I really hope I find something besides crab trap pieces at 18 inches. Best of luck to you all! Good hunting!
OBN, glad to hear you doing better. You always have such good information and have added so much to my knowledge of this sport ( addiction? ). You really should write a few books of your own on detecting. I guarantee I would be one of the first ones to buy.