I always carry a roll of blue painter tape and a sharpie in my dive kit. I can put a piece of tape and my name on a tank (I own my own tanks but they still look like everyone else's). When the tank is used I tear off half the tape. So it still has my name but not my full name. Helps with identifying my tanks and with knowing which tanks are full. Another trick (but probably not a good idea on the boat) is if you bang the tank on the ground a full tank will sound differently than an empty tank. The guys down at ScubaToys posted a video about this: https://www.youtube.com/watch?v=WbOXM8cPFEM.
As a way to show something is cool I just give an OK or maybe a double OK. An alternative is to use the Shaka hand sign. If in doubt, go over the hand signals before you get in the water as part of your buddy check. At that point you could agree on anything to mean 'cool'.
As a way to show something is cool I just give an OK or maybe a double OK. An alternative is to use the Shaka hand sign. If in doubt, go over the hand signals before you get in the water as part of your buddy check. At that point you could agree on anything to mean 'cool'.