What should a diver do if they surface having exceeded their no-decompression limit?

The diver should remain on the surface, breathe oxygen, and monitor themselves for the signs and symptoms of decompression sickness. They must remain out of the water for at least 24 hours. They should not re-enter the water to attempt an emergency decompression stop after the fact.

What surface interval credit does the RDP use compared to the US Navy tables?

The RDP is based on a surface interval credit of 60 minutes, while the US Navy tables used a surface interval credit of 120 minutes. This difference means the two systems are not interchangeable — pressure groups from one cannot be used with the other.

How does cold water affect the no-decompression limit on the RDP?

When diving in cold water or under physically demanding conditions, you must treat yourself as one pressure group higher than the table calculates. Plan the dive conservatively and apply the adjustment after finding your actual ending pressure group before entering the surface interval step.

Does the RDP allow longer or shorter repetitive dives than the US Navy tables?

The RDP allows longer repetitive dives than the US Navy tables. Because the RDP uses a 60-minute surface interval credit tissue compared to the Navy's 120-minute tissue, it calculates nitrogen as offgassing more quickly during the surface interval. This produces less residual nitrogen, which means less time is added to the next dive as RNT and more adjusted no-decompression limit remains.

What is the minimum surface interval required before flying after multiple days of diving?

After multiple dives or multiple days of diving, the minimum pre-flight surface interval is 18 hours. After a single dive the minimum is 12 hours. After any dive requiring emergency decompression the minimum is at least 18 hours, and waiting longer is strongly recommended.

RDP Practice Exam — PADI IDC and Divemaster Study Notes

Mixed RDP Practice Exam

12 questions covering the same mix you will face in a real PADI IDC written exam — decompression theory, RDP rules, and eRDPml operational questions. Answer each question, then check it individually. Your score appears once all 12 are answered.

Decompression Theory and RDP Rules — Q1 to Q6

Q1 Upon surfacing from a dive to 100ft a diver realises they have exceeded their no-decompression limit by 8 minutes. What should they do?

Re-enter the water and make an emergency decompression stop of at least 15 minutes, longer if air supply permits, then remain out of the water for at least 24 hours
Re-enter the water and make an emergency decompression stop of 8 minutes, then remain out of the water for at least 6 hours
Remain on the surface, breathe oxygen and monitor for the signs and symptoms of DCS. Remain out of the water for 6 hours
Remain on the surface, breathe oxygen and monitor for the signs and symptoms of DCS. Remain out of the water for 24 hours

Q2 The RDP is based on a surface interval credit of _______ minutes, while the US Navy tables used a surface interval credit of _______?

14 / 12
14 / 120
14 / 60
60 / 120

Q3 The pressure groups on the RDP and the Navy dive tables both use letters to designate an elevated level of nitrogen in the body after a dive. They are:

Interchangeable before calculating surface interval only
Interchangeable either before or after calculating surface interval
Not interchangeable because they use a different mathematical/decompression model
None of the above

Q4 When diving at altitude it is important to know:

The adjusted barometric pressure
The altitude
The type of water you are diving in
Both A and B

Q5 When diving to a depth of 60ft in cold water, your no-decompression limit for the dive is:

55 mins
40 mins
30 mins
25 mins

Q6 When compared to Navy tables, the RDP allows _______ with regards to repetitive dives?

Longer repetitive dives
Shorter repetitive dives
The same NDL on repetitive dives
The option to use a dive computer on a repetitive dive

eRDPml Operational Questions — Q7 to Q12

Q7 After a dive you are in pressure group F. If you then take a 20-minute surface interval, what would your adjusted no-decompression limit be for a dive to 60ft?

55 mins
36 mins
39 mins
30 mins

Q8 Use the eRDPml You complete a dive and a surface interval of 49 minutes, putting you in pressure group J. What would your adjusted no-decompression limit be for a dive to 43ft?

79 mins
61 mins
62 mins
47 mins

Q9 You complete a dive that leaves you in pressure group S. How long a surface interval must you take if you want to do a second dive to 50ft for 50 minutes?

50 mins
41 mins
42 mins
43 mins

Q10 You have just completed a dive ending in pressure group R. If you take a 45-minute surface interval, how deep could you go for a second dive of 50 minutes?

40ft
45ft
50ft
55ft

Q11 Following all RDP rules, how long will it take in total — from the start of the first dive to the end of the last dive — to complete the following three dives in one day: 40ft for 120 mins, 90ft for 15 mins, 36ft for 100 mins? Assume minimum surface intervals and include all required safety stop time.

481 mins
376 mins
484 mins
475 mins

Q12 You are planning a three-level multilevel dive at 110ft, 70ft, and 30ft. You want to spend the maximum time RDP rules allow at each level. How long will you be underwater in total, including any required safety stop time?

125 mins
80 mins
74 mins
44 mins

Realistic PADI IDC RDP Practice Exam

Mixed RDP Practice Exam