Originally Posted by williamhj
Weight would be my guess too. Even with heavier nymphs I'm often surprised how much I can underestimate the depth of the fly. Most of the time if I'm not ticking bottom I'm not deep enough. It's hard to know for sure though, there are a lot of factors. Accepting the book offer might be a good idea.
I have had a guy tell me for nymphs, if you are not losing flies you are not deep enough lol it is kind of true for the areas I fish though.