Of all the DIR subjects I get asked about, the one that demonstrates the most discussions seems to be ratio deco. I've written, somewhat extensively, in the past about how ratio deco is applied at the Tech 1 level; that is, for decompression dives between 30 metres and 48 metres.
Most people who are diving deeper than this know that a similar strategy can be applied when diving deeper. Tech 2 gives you so much more information that your certification card is limited by the depth you have been trained to, rather than any limitations in the tools you are given to plan deeper dives.
However, this is all well and good for the deep diving techie diver, but it’s not particularly useful for the shallow, recreational diver. How we can make use of ratio deco at the recreational level, to make diving safer, or at the very least give us an extra tool to get out of the water safely.