PADI Divemaster Certification Practice Exam

How is the adjusted bottom time (ABT) determined for a repetitive dive?

1. Through surface conditions

2. Using prior dive and surface interval information

3. By adjusting for air temperature

4. Checking visibility underwater

The correct answer is: Using prior dive and surface interval information

The adjusted bottom time (ABT) for a repetitive dive is determined by using prior dive and surface interval information. This approach takes into account the metabolic load placed on the body by previous dives, as well as the surface interval that follows, which plays a crucial role in allowing the body to off-gas nitrogen accumulated during previous dives. When calculating ABT, divers typically refer to dive tables or a dive computer that incorporates these variables. The prior dive data helps ascertain how much nitrogen is still in the diver’s system, which can affect the limits for additional dives and the related bottom times. The surface interval allows for some clearance of nitrogen, and its length will adjust maximum allowable bottom time on subsequent dives. Other factors such as surface conditions, air temperature, or underwater visibility, while relevant to the overall diving experience and safety, don't directly influence the calculation of adjusted bottom time for repetitive dives in the same way that prior dive history and surface intervals do.