Dive Computer - Algorithms

Algorithms

Algorithms vary by model from each manufacturer but only a few algorithms have been developed, for example the Bühlmann decompression algorithm. The algorithm used may also be a modification of an existing algorithm and may be an important consideration in the choice of a dive computer. Dive computers using the same internal electronics are often marketed under an array of brand names.

The algorithm used helps to minimise a diver's risk of decompression sickness (DCS). Diving scientists use known data that is recorded and averaged from previous divers to create an algorithm. The computer measures depth and time, then uses the algorithm to determine decompression requirements and no-stop times. An algorithm tries to account for magnitude of pressure reduction, repetitive exposures, rate of ascent, and time at altitude. Some algorithms may not be able to account for age, previous injury, ambient temperature, body type, alcohol consumption, dehydration, and other factors such as patent foramen ovale, when determining the decompression requirements, while others may attempt to compensate for temperature and workload by having sensors that monitor ambient temperature and cylinder pressure.

As of 2009, the newest dive computers on the market use:

• Liquivision X1: V-Planner Live: VPM-B Varying Permeability Model and GAP for X1: Bühlmann GF (Buhlman with Gradient Factors)
• Mares: Mares-Wienke Reduced Gradient Bubble Model
• Pelagic Pressure Systems: modified Haldanean/DSAT Database or Bühlmann ZHL-16C(called Z+)
• Seiko: Bühlmann ZHL-12 + Randy Bohrer
• Suunto: Suunto-Wienke Reduced Gradient Bubble Model
• Uwatec: Bühlmann ZH-L8 /ADT (Adaptive), MB (Micro Bubble), PMG (Predictive Multigas), Bühlmann ZHL-16DD (Trimix)
• Heinrichs Weikamp OSTC and DR5: Bühlmann ZHL-16 and Bühlmann ZHL-16 plus Erick Baker's Gradient Factors deep stop algorithm both for open circuit and fixed set point closed circuit rebreather.