Part of debriefing a skill effectively is to explain to the students what mistakes they made and the solution. In all diving, but technical diving in particular, it is vital that we correctly identify the (sometimes more complex) problem(s) so that the student understands the potential risk. Likewise, the solution must be a clear statement explaining the correction and reassuring the students that using the correct technique will minimise risk.
Here is a very simple example that applies to both recreational divers and technical divers:
“I didn’t see bubbles coming from your mouth (an indicator of the problem) when you first switched regulators. Don’t forget, lung expansion injuries can occur if you hold your breath (the underlying problem), even during a short ascent. So keep your airway open by releasing a constant stream of small bubbles (the solution), then if you do accidentally ascend while a regulator is out of your mouth you won’t damage your lungs (the reason for the solution)”
Lack of bubbles is not the problem, it is just the sign we look for to indicate that the diver’s airway is open.
Some of this detail may or may not be necessary depending on the divers’ level and knowledge, but find out, don’t presume.
Oh and by the way, if you are thinking that tec divers should know not to hold their breath, you are correct. Even so, it is still a common problem. With experienced divers, I try to allow time for self-correction, when possible. Experienced divers are often much calmer than new divers, their breathing rate is slower and more controlled, so it takes a little time to see the exhaled bubbles.
How about a rebreather example, again this one can apply to both recreational and technical rebreather divers and I have chosen an example that applies to all units:
“When you went back onto the rebreather loop after the open circuit bailout, you didn’t look at your displays (indicator of the problem). If you don’t check your displays you won’t know whether the loop content is breathable (the underlying problem). You need to make sure that the rebreather is functioning correctly, before you breathe from it otherwise you may breathe a gas that has too much, too little oxygen or an unknown amount (if the sensors aren’t working correctly) or too much CO2. (the reason for the solution) so take the time to look carefully and check everything is working correctly each time before you breathe from the loop (the solution).”
Again, although not looking at the displays tells the instructor that the skill has not been performed correctly, that is not what has the potential for harm, so we need to elucidate further. In this example, you may need to tell divers to look in specific places, for specific information on different units, but I have kept it generic for this purpose. Sometimes they “look” at the displays, but they don’t “see” anything – which has the same problem, of course.
Of course, there are many ways to get the same message across, these are just examples. But breaking it down in this way for yourself is a useful tool to help you to analyse ways of making your debriefings clearer and helping your students.