Gradient Factors – A Simplified Primer

I am sharing this excellent article by ‘Doppler’ as it really covers the essentials of understanding Gradient Factors in modern Buhlmann decompression algorithms. In conjunction with Eric Baker’s ”Understanding M-Values’, this forms essential reading for any advanced diver seeking to utilize Buhlmann GF on their dive planning software, or technical diving computers like the Petrel or XDeep.

EXCERPT:

All dives are decompression dives, ergo all divers are decompression divers. Our acknowledgement of this and the depth of that acknowledgement can greatly influence our behavior when we dive: most specifically, our ascent behavior. How deep we dive, what gases we breathe, and how long we spend at depth vary considerably from dive to dive; but all dives share one common threat for individual divers: the risk of getting bent.

Smart divers consider many factors when planning dives, many of which help to alleviate that risk. One is choosing to dive a “conservative profile.” I guess there are many interpretations of what that means… but for our purposes here, it means choosing a decompression algorithm that’s proven, and choosing a setting for that algorithm that will generate stress-tolerant dive tables.

Many PDC (personal dive computers) use a Bühlmann ZHL-8 or ZHL-16 algorithm to model decompression stress in divers and their decompression obligation on ascent.