Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
... and I'm bringing bagpipes ...
... Bob (Grateful Diver)
I personally only use a rattle to communicate with my students when conducting OW classes. The rest of the time it is hand, body or light signals. I was on a liveaboard trip a few years ago in which a gent (used loosely) had a little pointer stick. It was fine for that application, until he learned that he could use it to easily tap his tank. For the rest of the trip all's I heard was "tap, tap, tap..... tap, tap, tap....." as he would use it to get his buddy's attention, constantly, to the point it started to grate on my nerves.