59
The no-decompression limits in the U.S. Navy tables are based upon six theoretical compartments for single dives, and one compartment
for surface intervals and repetitive dives. If you are familiar with table theory, you may know that they are characterized by half times
(i.e. the time required for 50 % equilibration to a pressure change) ranging from 5 minutes to 120 minutes.
The instrument includes the same six compartments, and two additional compartments for an increased range of the mathematical
model. The calculations are based on all eight compartments for all phases of diving, including surface intervals and repetitive dives.
The dive computer’s half times range from 2.5 to 320 minutes. The multi-level tissue calculations are based on modified Haldanean
principle.
ALTITUDE DIVING
The atmospheric pressure is lower at high altitudes than at sea level. After traveling to a higher altitude, the diver will have
additional nitrogen in his body, compared to the equilibrium situation at the original altitude. This “additional” nitrogen is
released gradually in time and equilibrium is reached within a couple of days.
Before high altitude diving the instrument must be set to high altitude diving mode to take this into account. The maximum
partial pressures of nitrogen allowed by the mathematical model of the dive computer are reduced according to the lower
ambient pressure. As a result the allowed no-decompression limits are considerably reduced.
