PADI Divemaster Certification Practice Exam

What must be calculated when given three or more dive depths, times, and surface intervals?

1. Pressure groups and air consumption rates

2. Surface intervals and swim times

3. Adjusted no decompression limits (ANDLs) and adjusted bottom times (ABTs)

4. Visibilities and current strengths

The correct answer is: Adjusted no decompression limits (ANDLs) and adjusted bottom times (ABTs)

When considering three or more dive depths, times, and surface intervals, calculating the adjusted no decompression limits (ANDLs) and adjusted bottom times (ABTs) is crucial for ensuring diver safety and adherence to diving tables or computer algorithms. The necessity for ANDLs arises from the cumulative effect of multiple dives on the body's nitrogen saturation levels. Each dive adds to the total nitrogen absorption, which can increase the risk of decompression sickness if not managed properly. Therefore, accurately assessing the total exposure from the series of dives allows divers to adjust their no-decompression limits accordingly. This ensures that they do not exceed safe limits during subsequent dives. Similarly, adjusted bottom times take into account the time spent at various depths and the surface intervals between dives. By considering both factors, divers can better plan their remaining dive times, ensuring that they remain within safe limits for the depth they are diving. In this context, pressure groups and air consumption rates, surface intervals and swim times, or visibilities and current strengths do not pertain directly to the critical adjustments required when planning multiple dives. While they may be important factors in other aspects of diving, they do not address the essential calculations that relate to safe diving practices in a multi-dive scenario.