I had a similar "ticking" sound whenever I sailed or motored on my 1980 H30. It turned out that one of the prop shaft zincs had come loose but had not fallen off and slipped down to where it was touching the prop strut. As the shaft turned, during either sailing or motoring, the loose zinc would "click/tick" against the strut. Fortunately, this happened late in the season shortly before haul-out so there was no damage to the strut.
