Three algorithm families: Bühlmann ZHL-16 with GF, VPM-B, and RGBM. Most common GF Low/High: 30/85 or 40/75. DAN Europe: 40,000 dives analysed. Shearwater Perdix, Ratio iX3M, Divesoft Liberty.
Choosing between the Perdix, Shearwater, OSTC, Ratio, or Suunto involves comparing algorithms (Bühlmann ZHL vs. RGBM), hardware reliability, and ease of use. Gradient Factors (GF) are the most debated point: what values to use, how to adjust them according to the dive profile, and the latest recommendations from the technical community. Documented failures such as data loss on the Perdix generate mistrust.
Technical dive computers implement three main algorithm families: Bühlmann ZHL-16 with gradient factors, VPM-B, and RGBM. The Bühlmann model with GF is the most widespread because it allows adjusting conservatism via two parameters (GF Low and GF High), with combinations such as 30/85 or 40/75 being the most common. DAN Europe studies on nearly 40,000 dives reveal that decompression sickness risk factors include not only the algorithm but also the diver's physical condition, water temperature, and effort during ascent.