We only got one of these. It's not hard to pass the PADI Open Water course, after all. If anything, it's too easy. You see a lot of badly-trained divers whose instructors have probably got fed up, and certified them before they needed certifying themselves. In a mental institution. It can be hard work when someone just doesn't get it.
There's some basic Physics knowledge to get your head around, but it's very basic stuff. As long as you can swim, and breathe underwater, you can pass the course.
We had a likeable fellow called Father Manuel on board one week; the local Catholic priest. He had friends visiting him from the States in a couple of weeks, and they wanted to dive. So he joined us for his OW course. Gerd had another OW to finish, as the girl needed to fly back to Manila soon. So I looked after Manuel (I refused to call him Father, as everyone else did, as I'm an atheist) and taught him some of the basic skills in shallow water: how to recover your regulator and clear it before breathing again, clearing water from your mask, etc. He struggled with some of these, and I knew we'd have problems. It'd be a miracle if he passed, and it'd require the patience of a saint to get him certified. And Gerd doesn't have the patience of a saint...he can get frustrated if he repeatedly demonstrates a skill and a student repeats it completely wrong. I've swallowed more than my fair share of Philippines Seawater laughing at the scenarios...students looking wide-eyed and baffled, Gerd looking across at me with a dazed frown. It must drive him mad.
So by the fourth day with Manuel (the course should take 3 days) I could see Gerd approaching the far end of his tether. The priest gets a little flummoxed at times, and stares into space underwater. When you try to get his attention, he moves his whole body to look at you, instead of turning his head. When I asked him why, he said the regulator kept popping out of his mouth. He hadn't realised that the mouthpiece is ergonomically designed to be held between your teeth. So no wonder he'd been frozen in fear half the time.
Manuel was nearly done though, and it was satisfying to see him improve. Only a few simple skills to complete, one of which was the CESA (Controlled Emergency Swimming Ascent); this involves a vertical swim to the surface on one breath of air, simulating an out-of-air emergency. It's usually done over 10 metres, you make a sound to show the instructor you are slowly exhaling, so that the expanding air in your lungs doesn't burst them (if you hold your breath and ascend, you're going to be in serious trouble). It's not difficult. You ascend as slowly as you can to prevent nitrogen bubbles coming out of solution too quickly from within your body's tissues and getting trapped in them. This is the dreaded Bends. I'll give a basic explanation: the air we breathe is under 1 Bar of Atmospheric Pressure. For every 10m you descend underwater, it increases by 1 Bar. So if you're 30m below the surface, you're breathing air at 4 Bar of ATM. Four times the pressure equals four times the density of the air you breathe (you get the same volume in a breath through the scuba unit's regulator). This means you're getting four times as much Nitrogen. When we breathe normal air, 21% is Oxygen and 79% Nitrogen. Oxygen we use and absorb into the bloodstream. Nitrogen is uselss to us. On the surface we simply breathe it back out; underwater at depth, we absorb it into our tissues in solution. There is a limit to how much we can safely absorb in a given period of time, and a dive computer will tell you when you should be making your ascent. The deeer you go, the quicker you absorb Nitrogen, and the shorter the dive. Now when you decide to come back up, you do it very slowly; a rate of 18m per minute is considered safe. Through respiration the Nitrogen comes out of solution back into the lungs, and we expel it. Come up too quickly, and the Nitrogen comes out of solution too quickly and larger bubbles form. These can then block arteries or chambers in your heart. Deadly. Think of shaking up a bottle of Coke and then taking the top off. That Carbon Dioxide has been locked into the solution under pressure, and fizzes violently on coming out. Much the same would happen to your blood in a rapid ascent. It's not a nice way to die.
I hope that didn't bore you too much; back to Manuel. So the skill involves a slow ascent, not holding your breath, keeping one arm up above you like Superman (to protect your head from surface obstacles)...and your other hand on the deflator button to release expanding air from your BCD as you come up, thereby keeping your ascent rate safe. Gerd demonstrated it 3 times. Manuel fucked it up completely 3 times. I demonstrated it and waited at the surface for the fireworks.
Manuel came up and floated on his back, looking exhausted. Eyes raised to the sky, maybe he was looking for help from The Boss? Gerd slowly pulled off his mask. "Father Manuel, I must ask you to concentrate. Already I demonstrate this skill three times" he said, tether end reached. "OK" said Manuel "I finish. Is enough for me." Gerd was a little shocked, but I'd seen it coming. The Filipinos are very respectful to each other, and don't understand our Western aggression and forcefulness. He'd had enough of being shouted at. I could see both sides to this one. Gerd gets frustrated, and Manuel just wasn't cut out for learning diving in this manner. A pity. I tried to convince him to finish the course, and told him Gerd only gets annoyed because he wants to turn out good divers. To no avail; Manuel was finished.
Gerd asked me what I thought as we walked back from the pier. I said I could see both sides of the story, and maybe he'd better stop teaching Discover Scuba and Open Water if it got to him. He said that's what he was thinking. I reckon life'd be a lot easier, if a little less lucrative, if he does.