Scuba Diving Dive Planning and Tables 2 — Questions and Answers
Question 1: What is the minimum surface interval recommended between dives when using the PADI RDP?
- It depends on the pressure group — tables provide specific minimum intervals (Correct answer)
- Always 30 minutes
- Always 1 hour
- Always 2 hours
Correct answer: It depends on the pressure group — tables provide specific minimum intervals
The RDP table provides the minimum surface interval required based on the diver's pressure group after the first dive and the planned depth of the next dive.
Question 2: What is 'total bottom time' (TBT) in repetitive dive planning?
- Residual nitrogen time plus actual bottom time of the current dive (Correct answer)
- The total time spent underwater across all dives in a day
- The planned bottom time before entering the water
- The time from the surface to reaching maximum depth
Correct answer: Residual nitrogen time plus actual bottom time of the current dive
Total bottom time equals the residual nitrogen time (from prior dives) added to the actual bottom time of the current dive, used to find the ending pressure group.
Question 3: What effect does diving at altitude have on standard sea-level dive tables?
- Tables must be adjusted because ambient pressure is lower at altitude (Correct answer)
- No adjustment is needed
- Tables become more conservative at altitude
- Altitude has no effect on nitrogen absorption
Correct answer: Tables must be adjusted because ambient pressure is lower at altitude
At altitude, lower ambient pressure means sea-level tables underestimate decompression risk, so altitude-specific tables or adjustments are required.
Question 4: What is 'decompression sickness' (DCS) caused by?
- Nitrogen bubbles forming in tissues and blood when pressure is reduced too quickly (Correct answer)
- Breathing too much oxygen at depth
- Water pressure crushing the joints
- Hyperventilation during ascent
Correct answer: Nitrogen bubbles forming in tissues and blood when pressure is reduced too quickly
DCS occurs when dissolved nitrogen comes out of solution and forms bubbles in tissues and the bloodstream due to an ascent that is too rapid or exceeding NDLs.
Question 5: Why should flying after diving be delayed?
- Cabin altitude reduces pressure, increasing DCS risk from residual nitrogen (Correct answer)
- Airplane engines interfere with dive computers
- Ears cannot equalize after nitrogen saturation
- It is only restricted for deep dives, not recreational dives
Correct answer: Cabin altitude reduces pressure, increasing DCS risk from residual nitrogen
Aircraft cabins are pressurized to the equivalent of 6,000–8,000 feet, which is lower than sea-level pressure, promoting nitrogen bubble formation from residual tissue nitrogen.
Question 6: According to PADI guidelines, what is the minimum wait before flying after a single no-decompression dive?
- 12 hours (Correct answer)
- 4 hours
- 24 hours
- 8 hours
Correct answer: 12 hours
PADI recommends a minimum surface interval of 12 hours before flying after a single no-decompression dive to allow sufficient nitrogen off-gassing.
Scuba Diving Dive Planning and Tables 2
What is the minimum surface interval recommended between dives when using the PADI RDP?