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

Maximum depth allowed without special training

Answer

Minimum surface interval between dives

Answer

Maximum number of dives per day

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

The team of divers on a given dive

Answer

A measure of the tank pressure used during the dive

Answer

The depth group assigned at the start of 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 stop at the bottom to check equipment before ascending

Answer

A mid-water pause to equalize ear pressure

Answer

A surface rest period between repetitive dives

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

The time needed to refill tanks between dives

Answer

Nitrogen released during a safety stop

Answer

The rate at which nitrogen leaves tissues during ascent

Question 5

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

Accepted Answer

30 feet (9 meters) per minute or slower

Answer

60 feet (18 meters) per minute

Answer

100 feet (30 meters) per minute

Answer

15 feet (4.5 meters) per minute

Question 6

Why should the deepest dive of the day be planned first?

Accepted Answer

To minimize residual nitrogen for subsequent shallower dives

Answer

Because air consumption is highest in the morning

Answer

To get the hardest dive done while rested

Answer

Because visibility is best at depth earlier in the day