Dual Algorithm Technology

Dual Algorithm was designed to maximise your dive times regardless of the type of diving you do.

All dive computers use an algorithm to calculate your crucial information such as your bottom time based on depth or gas mix. This algorithm has to allow for a enormous range of physiques, dive profiles, environmental situations and eventualities so manufacturers need to add a buffer of safety to compensate. The result is a less than optimised algorithm that is safe for all recreational dives.

Oceanic dive computers are different. Instead of one there are actually two algorithms, each designed to offer a more optimised calculation to maximise the bottom time for their intended use without compromising on your safety. An added bonus of this flexibility is that Oceanic computers can be altered via the menu system to closely mimic the behaviour of other brands of computer

Oceanic Dual Algorithm


This graph illustrates two things:

  1. How much choosing the right algorithm can maximise your bottom dive
  2. Dual algorithm can be used to closely match the dive profiles of other dive computer brands

The graph is based on a single dive to 30m and shows the No Decompression Limits (NDL) recorded at certain depths during the ascent. The two algorithms are divided into bands, red for Pelagic Z+ and blue for Pelagic DSAT. Each band encapsulates different brands of dive computers to show which algorithm can be used to produce a similar dive profile as that brand.

The horizontal scale shows the elapsed dive time and the vertical scale shows the NDL at the different depths marked on the graph. For example after 42 minutes the diver was back at 12m where the Oceanic computer using the Pelagic DSAT algorithm had a 65 minute NDL but the closest competitor had 42 minutes and the worst just 25 minutes. Which computer would you want to be using if you finished a dive on an amazing reef with plenty of air left?

Choosing the right Algorithm

Making the right choice of algorithm for your dive can have a big impact on your dive time so here are the basics:

Choose Pelagic DSAT for liberal recreational diving. The Pelagic DSAT Algorithm safely maximises dive time for repetitive, multi-level recreational diving. This algorithm relies on the human Doppler studies used to develop PADI’s Recreational Dive Planner (RDP), and has been the basis of our Dive Computers and other manufacturer’s computer algorithms for many years.

If you want to add a little conservatism to the algorithm you can also adjust the Tissue-Loading Bar Graph Alarm and Conservative Factor Setting within the computer to reduce bottom time but increase safety

Choose Pelagic Z+ for a conservative approach to recreational diving or maximised bottom time for deeper dives and decompression diving. When applied to standard recreational diving, the Pelagic Z+ Algorithm increases the conservative factor of the dive computer by 15-20% but when doing deep and decompression diving the Pelagic Z+ algorithm offers a liberal bottom time. The Pelagic Z+ uses the Buhlmann ZHL-16C database, which was conducted to meet the more rigorous demands of repetitive, cold-water decompression diving at altitude. The Pelagic Z+ mode maximises dive times at depth without penalties.

Dive in sync with any buddy, anywhere.

Because the Dual Algorithm allows you to adjust the algorithm basis and its conservatism, you can adjust the dive computer to closely match just about any other computer on the market, allowing you and any buddy to always dive in sync. Diving the same profile increases safety for both divers, and eliminates the need for one person to conduct a much longer or deeper stop when buddying with someone wearing a more liberal dive computer. On repetitive dives, there is no more waiting for the more conservative dive computer to clear. Both buddies will be ready to enter the water at the same time and can continue to dive the same profiles. You can’t control which dive computer your buddy wears, but you can control your ability to dive the same profile.

A note about deep stops:

Both algorithms allow (user ON/OFF option) credit for deep stops for No-Decompression dives in keeping with the data of Morroni et al (2004) and Bennett et al (2007). No penalty is given if the diver skips the deep stop, but it is strongly recommended that a shallow safety stop be made with or without the deep stop in keeping with the experiments of Pilmanis (1975).

It is important to note that neither algorithm provides deep stops for decompression dives since there is ample experimental data [Blatteau et al (2005), Gerth et al (2007), and Gutvik et al (2007)] that indicates that this practice often produces an increase in the risk of DCS.

For more information and detailed “Liberal vs Conservative” algorithm comparison charts – see Scuba Diving Magazine’s ScubaLab “Digging Deep on 2009’s New Dive Computers”.

DSAT published & protected by Diving Science & Technology