I was out observing last night in subpar skies, and decided to try sketch M 51 through my 18", without referring to any image to identify features. As I was working through the sketch, I did notice bits and pieces of the faint connecting arms, but most of the arms of the main member of M 51 wrapped around into a ring, indeed! The contrast on the "inside" of the ring was so poor, that I couldn't see the spiral structure -- just the ring and a few off-shoots and bits of the connecting arm. It's only after going half way through my sketch of the bright regions and saying to myself "this does not look like M 51", that I tried and found the lower-contrast regions where the arms forming the "ring" spiral out of the core. so when I tried to trace the arms going into the core, I marked them somewhat incorrectly, indicating that I wasn't really seeing exactly where they were going into but only had a general sense of which way they were going.

So I didn't exactly see Herschel's Ring, but I think I did pick up the central theme of it.