A decompression model is the theoretical guidelines within which a diver must stay to avoid getting decompression sickness. It’s based on several factors – the dive profile (maximum dive-depth and how much time the diver stays at each depth, ascent rate etc), dive profiles over previous days and the decompression algorithm.
However – not all dive computers follow the same decompression algorithm – whilst the end-goal of all algorithms is the same: to keep the diver safe and free from decompression sickness, they vary slightly in terms of how they are calculated which in turn affects how conservative they are.
In the case of the Garmin Descent MK1 it operates via the Buhlmann ZHL-16C algorithm and also includes the modern gradient factors approach, which was first developed by one Erik Baker.
The Buhlmann ZHL-16C incorporates 16 theoretical tissue compartments with differing on and off gas rates. It is the speed of the off-gasing that determines how deep and how long each stop should be.
This is a well-known, moderately conservative algorithm that’s been in use for over three decades. Users have the option to customise it by applying different gradient factors which gives the option to configure stops to be where you want them to.
However, if that sounds over-complicated to you – don’t even sweat! The standard algorithm setting is ideal just the way it is.
You can also make more simple adjustments by switching between 3 conservatism settings. (More conservative = shorter bottom time and longer ascent time – it’s good for inexperienced divers or those with pre-existing medical conditions).