Three parts are required to become certified: knowledge development, skill practise and open water diving. You can choose to do each part locally, on holiday or alternate between them.
The next day it was on to technical sidemount, which means adding our deco 50-percent oxygen and 100-percent oxygen tanks on either side. This increases your profile underwater so you must keep the tanks as trim as possible against your body. You have a couple of clips on each side of your waist. As you breathe down your tanks and they become positively buoyant, you adjust your tank position to the second clip position. The aim here is to be as streamlined as possible. Every few minutes you also switch your breathing from one tank to the other. That way the pressure in each tank runs down at roughly the same rate, and if there is a failure with either tank or regulator, you’ll still have gas to breathe. As with all new things, building up experience is key to comfort and enjoyment. I spent the next few days doing deco dives with the sidemount rig, buddied up with Evolution co-owner David Joyce — a hugely experienced Tec diver and Trimix instructor. On one dive we visited the Japanese Mogami wreck down at 164 feet, where I was beguiled by the bits of old gas masks, uniforms and even a few bones we saw.
