I finally finished the independent learning section of the IDC. The portion consisted of about 340 questions, a couple of dozen articles and about seven centimetres of A4 in the instructor manual. Some of the articles were more than two decades old, but still more or less valid. And if that’s not impressive in these fast-paced times, consider this: although the basics of decompression theory originate from the beginning of the last century, same principles are applied today in the most modern dive computers.
We also got a quick glimpse at technical diving (tec for short) by trying out double tanks and other tec gear, and boy was it difficult. I’ve done a fin pivot (see a demonstration in Youtube) approximately a million times in my own and rental scuba gear, but the buoyancy/weight balance of the tec set was so completely different I didn’t even get close. On the other hand, the additional mass made it somewhat easier to control my depth. That may sound a bit odd to someone who has never dived, but it goes like this:
[a long explanation follows]
Whenever I’m underwater, there are two forces that affect my depth, namely gravity and the buoyant force of water supporting me. When these two are in balance, I can float around in same depth for as long as I want. However, the buoyant force is a bit complicated to manage.
As we know from elementary physics, the buoyant force of water depends on the volume of the object, which in this case is a breathing human. When I breathe in, my external volume changes somewhat. I then displace more water, become more buoyant than with my lungs empty. It may not sound like a big deal, but breath control is actually the most effective way to do depth changes in two to three metre range.
Now, throw in around 10 kilograms of extra weight (compared to my standard equipment), and the situation changes somewhat. The weight has to be countered with extra buoyancy, which in turn makes my breathing relatively less significant to my total buoyancy.
[a long explanation concludes]
Anyway, the experience was fun, and I was still able to control my depth with breathing well enough. The experience was fun, but right now I’m not sure technical diving is my choice. I still find a lot of interesting stuff within the limits of recreational fun diving, so there’s no incentive for me to go there – at least not yet.
Tomorrow we’ll be having a compressor and equipment maintenance workshop. Should be fun!
Tags: diving, instructor internship, PADI IDC, studies