Scuba Diving Dive Planning and Tables

Question 1

What is a no-decompression limit (NDL) in recreational scuba diving?

Accepted Answer

Maximum time at a given depth before a decompression stop is required

Answer

The no-decompression limit is the maximum bottom time at a specific depth that allows a direct ascent to the surface without mandatory decompression stops.

Question 2

What is a 'pressure group' on PADI's recreational dive planner tables?

Accepted Answer

A letter indicating the amount of residual nitrogen in the diver's body after a dive

Answer

A pressure group is a letter (A–Z) on the RDP table that represents the level of residual nitrogen remaining in a diver's tissues after a dive.

Question 3

What is a 'safety stop' and at what depth is it typically performed?

Accepted Answer

A 3-minute pause at 15 feet (5 meters) to allow excess nitrogen to off-gas

Answer

A safety stop is a precautionary 3-minute pause at 15 feet (5 meters) recommended at the end of every dive to allow additional nitrogen off-gassing before surfacing.

Question 4

What does 'residual nitrogen time' (RNT) account for in dive planning?

Accepted Answer

Nitrogen still dissolved in tissues from previous dives that counts against the next dive's NDL

Answer

Residual nitrogen time is the equivalent bottom time already 'used' due to nitrogen left from prior dives, which is added to actual bottom time when planning repetitive dives.

Question 5

What is the recommended maximum ascent rate in recreational scuba diving?

Accepted Answer

30 feet (9 meters) per minute or slower

Answer

Most training agencies recommend ascending no faster than 30 feet (9 meters) per minute to allow adequate nitrogen elimination and reduce decompression sickness risk.

Scuba Diving Practice Test

Scuba Diving Practice Test

Scuba Diving Dive Planning and Tables