Decompression Theory & Recreational Dive Planner

Question 1

When diving higher than 300metres on the RDP, what procedures must you follow between your planned dives?

Answer 1

When diving higher than 300metres on the RDP, you must dive at the lowest altitude first if changing altitude between dives.

Question 2

When diving with a buddy or group, whose dive computer NDL should be followed?

Answer 2

When diving with a buddy or group, you should follow the dive computer with the most conservative NDL.

Question 3

Can the theoretical pressure groups be transferred between the RDP table and the eRDPml?

Answer 3

Because the theoretical models and pressure groups are the same between the RDP table and the eRDPml they can be transferred.

Question 4

What is the minimum time a diver should wait to fly after diving according to the RDP, if the diver has been diving for consecutive days?

Answer 4

If the diver has been diving for consecutive days, they should wait a minimum of 18hours according to the RDP.

Question 5

Use the RDP to answer the following question

Divers descend at 08:30 and dive to 24metres for 20minutes. At 09:18 the divers descend on a second dive to 18metres for 32minutes.

What are the divers maximum allowable bottom times for a third dive to 17metres after a 58minute surface interval?

Answer 5

Use the RDP to answer the following question

Divers descend at 08:30 and dive to 24metres for 20minutes, ending in pressure group K on the RDP.

At 09:18 after a 28minute surface interval, ending in pressure group G on the RDP.

The divers descend on a second dive to 18metres for 32minutes, ending in press group V.

After a 58minute surface interval the divers end in pressure group I.

The divers maximum allowable bottom time for a third dive to 17metres will be 30minutes.

Question 6

Use the RDP to answer the following question

Divers make a first dive to 20metres for 40minutes. They will make a second dive to the same depth for 28minutes.

The divers also decide to make a third dive to 16metres for 42minutes.

What are the divers needed minimum surface intervals between dives 1 & 2 and between dives 2 & 3?

Answer 6

Use the RDP to answer the following question

Divers make a first dive to 20metres for 40minutes, ending in pressure group R.

They will make a second dive to 20metres for 28minutes in which they will need to begin the second dive in pressure group E.

The needed minimum surface interval between dive 1 (PG R) and dive 2 (PG E) is 1hour 8minutes.

The Divers second dive to 20metres for 40minutes will end them in pressure group T, in which they will need to begin the third dive in pressure group I.

The needed minimum surface interval between dive 2 (PG T) and dive 3 (PG I) is 48minutes.

Question 7

Use the RDP to answer the following question

Divers make a first dive to 25metres for 19minutes. The divers decide to ascend from the first dive because the conditions are strenuous diving against cold moving currents.

The divers relocate to calmer conditions for a second dive to 39minutes after a surface interval of 55minutes.

What is the recommended maximum allowable depth for a second dive according to the RDP table?

Answer 7

Use the RDP to answer the following question

Divers make a first dive to 22metres for 19minutes. Due to strenuous conditions against cold moving currents the dive is calculated 4metres deeper, ending in pressure group M.

The divers relocate to calmer conditions for a second dive after a surface interval of 55minutes, begining the dive in pressure group E.

The maximum allowable depth beginning in pressure group E for a dive of 39minutes is 16metres.

Question 8

Use the eRDPml to answer the following question

Divers plan to do a multilevel dive starting from 32metres, moving up to 19metres and then a final depth of 12metres.

How long will the divers be able to stay in total, including safety stop (if required) according to all the maximum time limits?

Answer 8

Use the eRDPml to answer the following question

Divers plan to do a multilevel dive starting from 32metres, in which they will have a maximum time limit of 17minutes.

The divers move up to 19metres, in which they will have a maximum time limit of 10minutes.

The divers final depth is at 12metres, in which they have a maximum time limit of 50minutes.

The divers require a safety stop giving them a maximum dive time of 80minutes.

Question 9

Use the eRDPml to answer the following question

Divers enter the water to do their first dive to 24metres for 27minutes at 11:05am.

If the divers use the minimum surface interval to plan for their second dive to 22metres for 25minutes, what time will they come back up to the surface after both dives?

Answer 9

Use the eRDPml to answer the following question

Divers enter the water to do their first dive at 11:05 to 24metres for 27minutes followed by a required safety stop..

They take a minimum surface interval of 1hour 17minutes.

The divers enter the water to do their second dive at 12:52 to 22metres for 25minutes followed by a required safety stop.

After both dives the divers come back to the surface at 13:20.

Question 10

Use the eRDPml to answer the following question

Divers plan a multilevel dive starting at 24metres for 22minutes, then move up to 20metres for 11minutes and a final depth of 12metres for 15minutes.

What is the ending pressure group at the end of this dive?

Answer 10

Use the eRDPml to answer the following question

Divers plan a multilevel dive starting at 24metres for 22minutes, ending at PG L after the first level.

Then the divers plan to move up to 20metres for 11minutes, which results in exceeding the no decompression limit.

The dive profile can’t be done.

Question 11

When does the RDP require the use of special procedures including the conversion of actual depth to theoretical depth?

Answer 11

The RDP requires special procedures above an altitude of 300metres, in which the altitude of the dive must be know to convert to theoretical depth tables.

Question 12

What is the relationship between the body and the Haldane decompression model?

Answer 12

There is no direct relationship between the body and the Haldane decompression model, however the relationship is implied based on actual dive data.

Question 13

What is a recommendation and general rule when planning depths over consecutive dives?

Answer 13

The recommendation and general rule when planning depths over consecutive dives, is to make the deeper dive before the shallow dive to avoid reverse profiling and bubble expansion.

Question 14

Who was the RDP tested by during its development and for what purpose?

Answer 14

The RDP was tested by the military divers during its development for the purpose of military diving.

Question 15

What is the main benefit of using the eRDPml over the RDP table?

Answer 15

A main benefit of using the eRDPml over the RDP table, is that the eRDPml offers multilevel dive planning, offering more precision when calculating theoretical nitrogen.

Question 16

Use the RDP to answer the following question

Divers plan to make two dives. The first dive to 30metres and the second dive to 18metres.

What is the divers no decompression limit for the first dive?

If the divers plan the first dive to be 15minutes followed by a 1hour 30minute surface interval, what is the no decompression limit for second dive going to be?

Answer 16

Use the RDP to answer the following question

Divers plan to make two dives. The first dive to 30metres and the second dive to 18metres.

The no decompression limit for the first dive to 30metres is 20minutes.

If the divers stay 15minutes (5minutes within the NDL) on the first dive this will put them in pressure group J.

After a 1hour 30minute surface interval the divers pressure group will reduce to B.

With a second dive in pressure group B to 18metres the no decompression limit is 45minutes.

Question 17

Use the RDP to answer the following question

Divers have just made two dives. The first dive to 25metres for 14minutes and the second dive to 23metres for 17minutes, with a 45minute surface interval between the dives.

What is the minimum required surface interval for a third dive to 21metres for 17minutes?

Answer 17

Use the RDP to answer the following question

Divers have just made two dives. The first dive to 25metres for 14minutes ended in pressure group F.

After a surface interval of 45minutes the pressure group was reduced to C.

From pressure group C, the second dive to 23metres for 17minutes the pressure group rose to P.

To achieve a third dive to 21metres for 17minutes the divers must be in pressure group H.

The minimum surface interval required between pressure group P & H is 39minutes.

Question 18

Use the RDP to answer the following question

Divers plan to make three dives.

The first dive will be to 29metres for 15minutes, followed by a 1hour 45minute surface interval.

The second dive will be to 21metres for 20minutes.

If this is followed by a 52minute surface interval, what will the no decompression limit for a repetitive dive to 21metres be?

Answer 18

Use the RDP to answer the following question

Divers plan to make three dives.

The first dive will be to 29metres for 15minutes ending in pressure group J.

Followed by a 1hour 45minute surface interval the reduced pressure group will be B.

The second dive will be to 21metres for 20minutes ending in pressure group N.

If this is followed by a 52minute surface interval the reduced pressure group will be E.

For a repetitive dive to 21metres in pressure group E the no decompression limit will be 22minutes.

Question 19

Use the eRDPml to answer the following question

Divers plan to make two dives.

The first to 26metres and the second to 18metres.

What is the no decompression limit for the first dive?

Answer 19

Use the eRDPml to answer the following question

Divers plan to make two dives.

The no decompression limit for the first dive to 26metres is 27minutes.

Question 20

Use the eRDPml to answer the following question

Divers plan to make two dives.

The first to 26metres and the second to 18metres.

The first dive is 21minutes and the divers have a 48minute surface interval before the second dive.

What is the no decompression limit for the second dive?

Answer 20

Use the eRDPml to answer the following question

Divers plan to make two dives.

The first dive to 26metres is 21minutes ending in pressure group M.

After a 48minute surface interval the pressure is E.

The no decompression limit for the second dive to 18metres is 38minutes.

Question 21

Use the eRDPml to answer the following question

Divers plan to make three dives.

The first dive will be to 23metres for 30minutes, followed by a 1hour 30minute surface interval.

The second dive will be to 22metres for 18metres, followed by a 1hour 20minute surface interval.

What is the no decompression limit for a repetitive dive to 16metres?

Answer 21

Use the eRDPml to answer the following question

Divers plan to make three dives.

The first dive will be to 23metres for 30minutes, followed by a 1hour 30minute surface interval ending in pressure group C.

The second dive will be to 22metres for 18metres, followed by a 1hour 20minute surface interval ending in pressure group C.

The no decompression limit for a repetitive dive to 16metres is 55minutes.

Question 22

What is another term for “theoretical tissue”?

Answer 22

Another term for theoretical tissue is “compartment”.

Question 23

What altitude can the RDP table be used at?

Answer 23

The RDP table can be used at an altitude lower than 300metres.

Question 24

What is the minimum recommended surface interval before flying after a series of dives?

Answer 24

The minimum surface interval before flying after a series of dives is 18hours.

Question 25

What are the maximum surfacing nitrogen levels in a model determined by?

Answer 25

The maximum surfacing nitrogen levels in a model are determined by the m-values.

Question 26

According to the RDP, when is a 3minute safety stop at 5metres required for a diver?

Answer 26

According to the RDP, a 3minute safety stop at 5metres is required for a diver who has dived to/or beyond 30metres, or within three pressure groups of their no decompression limit.

Question 27

Use the RDP to answer the following question

Divers plan to make three dives.

The first dive will be to 27metres for 17minutes, followed by a 1hour 10minute surface interval.

The second dive be to 22metres for 18minutes, followed by a 47minute surface interval.

What is the no decompression limit for a third dive to 17metres?

Answer 27

Use the RDP to answer the following question

Divers plan to make three dives.

The first dive will be to 27metres for 17minutes, followed by a 1hour 10minute surface interval ending in pressure group C.

The second dive be to 22metres for 18minutes, followed by a 47minute surface interval ending in pressure group G.

The no decompression limit for a third dive to 17metres is 34minutes.

Question 28

Use the RDP to answer the following question

Divers have just made two dives.

The first dive to 17metres for 51minutes and the second dive to 15metres for 41minutes, with a 50minute surface interval between them.

What is the minimum required surface interval before another dive to 15metres for 35minutes?

Answer 28

Use the RDP to answer the following question

Divers have just made two dives.

The first dive to 17metres for 51minutes ended in pressure group T.

After a 50minute surface interval the divers pressure group was I.

The second dive to 15metres for 41minutes ended in pressure group W.

The minimum required surface interval before another dive to 15metres for 35mins will be 1hour as highlighted in rule 6 of the RDP & eRDPml.

Question 29

Use the eRDPml to answer the following question

Divers plan to make two dives.

The first to 20metres and the second to 16metres.

What is the NDL for the first dive?

Answer 29

Use the eRDPml to answer the following question

Divers plan to make two dives.

The NDL for the the first is 45minutes.

Question 30

Use the eRDPml to answer the following question

Divers are planning a multilevel dive.

If the first level will be 28metres and you stay for 18minutes, what is the NDL for the second level at 20metres?

Answer 30

Use the eRDPml to answer the following question

Divers are planning a multilevel dive.

If the first level will be 28metres and you stay for 18minutes, the NDL for the second level at 20metres will be 12minutes.

Question 31

Use the eRDPml to answer the following question

Divers have just made two dives.

The first dive to 17metres for 44minutes and the second dive to 13metres for 55minutes, with a 51minute surface interval between them.

What is the minimum required surface interval for another dive to 11metres for 75minutes?

Answer 31

Use the eRDPml to answer the following question

Divers have just made two dives.

The first dive to 17metres for 44minutes ended in pressure group R.

After a 51minute surface interval the pressure group was H.

The second dive to 13metres for 55minutes ended in pressure group W.

The minimum surface interval for another dive to 11metres for 75minutes is 1hour as highlighted in rule 6 of the RDP and eRDPml.

Question 32

What is a compartment a term for?

Answer 32

A compartment is a term for a theoretical tissue.

Question 33

What is a Pressure Group (PG) a measure of on the RDP?

Answer 33

A Pressure Group (PG) is a measure of residual nitrogen in the body tissues.

Question 34

What procedures are to be followed for suspected decompression after a dive?

Answer 34

The procedures to be followed for suspected decompression sickness after a dive are to, remain on the surface, rest, be monitored for signs of decompression sickness, breathe 100% oxygen and do not dive for at least 24hours.

Question 35

Use the RDP to answer the following question

After a 32minute dive to 22metres, divers ascend to 5metres for a 3minute safety stop.

Upon exiting, the divers are in which pressure group?

Answer 35

Use the RDP to answer the following question

After a 32minute dive to 22metres, divers ascend to 5metres for a 3minute safety stop.

Upon exiting, the divers are in pressure group P.

Question 36

Use the RDP to answer the following question

Divers exit the water at 11:55 after a dive to 20metres for 43minutes.

They reenter the water for a 25minute dive to 16metres.

If they wish to make a third dive after a four-minute surface interval, what is the maximum depth they may dive and remain for 30minutes?

Answer 36

Use the RDP to answer the following question

The question cannot be answered with the information provided in the question as the surface interval between dive 1 and 2 is unknown.

Question 37

Use the RDP to answer the following question

Divers exit the water at 3:57pm after a dive to 25metres for 24minutes.

They reenter the water at 5:04pm for a dive to 16metres.

What is the maximum allowable bottom time for the second dive?

Answer 37

Use the RDP to answer the following question

Divers exit the water at 3:57pm after a dive to 25metres for 24minutes ending in pressure group O.

They reenter the water at 5:04pm after a 1hour 7minute surface interval reducing their pressure group to D.

For a second dive to 16metres maximum allowable bottom time is 53minutes.

Question 38

Use the eRDPml to answer the following question

Divers exit the water at 12:30pm after a dive to 23metres for 23minutes.

They reenter the water at 1:40pm for a dive to 22metres.

What is the maximum allowable bottom time for the second dive?

Answer 38

Use the eRDPml to answer the following question

Divers exit the water at 12:30pm after a dive to 23metres for 23minutes ending in PG M.

They reenter the water at 1:40pm after a 1hour 10minute surface interval reducing their PG to C.

For a second dive to 22metres the maximum allowable bottom time is 25minutes.

Question 39

Use the eRDPml to answer the following question

During a multilevel dive divers spend 10minutes at a depth of 32metres.

If they then wish to ascend to 24metres, what will the remaining no decompression time be?

Answer 39

Use the eRDPml to answer the following question

This dive cannot be made as it does not reach the multilevel ascent limit.

Question 40

Use the eRDPml to answer the following question

During a multilevel dive divers spend 32minutes at a depth of 20metres.

They then ascend to 12metres for a further 45minutes before exiting the water.

What would be the minimum required surface interval, if the divers wish to do a second dive to 14metres for 20minutes?

Answer 40

Use the eRDPml to answer the following question

During a multilevel dive divers spend 32minutes at a depth of 20metres giving them a PG after level 1 of N.

They then ascend to 12metres for a further 45minutes giving them a PG after level 2 of V.

The minimum required surface interval, if the divers wish to do a second dive to 14metres for 20minutes, would be 3minutes.

Question 41

What is the primary decompression related problem encountered when diving at altitude due to?

Answer 41

The primary decompression related problem encountered when diving at altitude is the increased difference in the partial pressures of dissolved nitrogen and the ambient pressure.

Question 42

A capillary depth gauge automatically compensates for high altitude because it operates on the basis of who’s law?

Answer 42

A capillary depth gauge automatically compensates for high altitude because it operates on the basis Boyle’s Law rather than on a direct measure of the ambient pressure.

Question 43

What are some factors can increase a diver’s probability of getting decompression sickness?

Answer 43

Some factors that can increase a diver’s probability of getting decompression sickness are things such as heavy exercise, drinking alcohol and being cold during a dive.

Question 44

A diver, after his only dive while on holiday, exists the water at 9:25am from a dive to 16metres for 40minutes.

What is the soonest time the diver should board a commercial airliner for their flight home?

Answer 44

A diver, after his only dive while on holiday, exists the water at 9:25am from a dive to 16metres for 40minutes.

The soonest the diver should board a commercial airliner for their flight home is 9:25pm.

Question 45

Because of the similarities of design, can repetitive group designations be transferred between the RDP and the US Navy tables?

Answer 45

Repetitive group designations can’t be transferred between the RDP and the US Navy tables, because the US Navy table credit is based on a 60minute halftime and the RDP table credit is based on a 120minute halftime.

Question 46

Use the RDP to answer the following question

Divers exit the water at 2:35pm after a dive to 24metres for 25minutes (already including a 3minute safety stop).

They reenter the water at 3:00pm for a dive to 18metres.

What is the allowable bottom time for the second dive?

Answer 46

Use the RDP to answer the following question

Divers exit the water at 2:35pm after a dive to 24metres for 25minutes (already including a 3minute safety stop) ending in pressure group N.

They reenter the water at 3:00pm after a 25minute surface interval reducing the pressure group to I.

The allowable bottom time for a second dive to 18metres is 30minutes.

Question 47

Use the RDP to answer the following question

Divers are planning a a series of three dives. Assume the divers use minimum surface intervals, follows the rules of the RDP and dives these exact profiles:

Dive 1: 18metres for 56minutes

Dive 2: 16metres for 39minutes

Dive 3: 16metres for 39minutes

In minutes how long will the entire profile take to complete from start to finish?

(You may ignore ascent times but not safety stops)

Answer 47

Use the RDP to answer the following question

Divers are planning a a series of three dives. Assume the divers use minimum surface intervals, follows the rules of the RDP and dives these exact profiles:

Dive 1: 18metres for 56minutes + 3minutes (PG W)

SI 1hour (PG I)

Dive 2: 16metres for 39minutes + 3minutes (PG W)

SI 1hour (PG I)

Dive 3: 16metres for 39minutes + 3minutes (PG W)

Total time: 263minutes

Question 48

Use the eRDPml to answer the following question

During a multilevel dive, divers spend 10minute at a depth of 37metres.

If they then wish to ascend to 18metres, what is their remaining no-decompression time during the shallow portion of the dive?

Answer 48

Use the eRDPml to answer the following question

During a multilevel dive, divers spend 10minute at a depth of 37metres resulting at PG L at level 1.

If they then wish to ascend to 18metres, their remaining no-decompression time during the shallow portion of the dive would be 23metres.

Question 49

Use the eRDPml to answer the following question

Divers have just made two dives, the first to 18metres for 44minutes and the second to 13metres for 55minutes, with a 51minute surface interval between them.

What is the minimum required surface interval for another dive to 12metres for 75minutes?

Answer 49

Use the eRDPml to answer the following question

Divers have just made two dives, the first to 18metres for 44minutes ending in PG R.

After a minimum surface interval of 51minutes the divers PG is H.

The second dive to 13metres for 55minutes ends in PG W.

The minimum required surface interval for another dive to 12metres for 75minute is 1hour as according to rule 6 on the RDP & eRDPml.

Question 50

Use the RDP to answer the following question

Divers complete a series of following dives.

Dive 1: 30metres for 15minutes, followed by a 45minute surface interval.

Dive 2: 25metres for 17minutes, followed by a 50minute surface interval.

Dive 3: 20metres for 15minutes.

What is the final pressure group and required number of safety stops after completing this series of dives?

Answer 50

Use the RDP to answer the following question

Divers complete a series of following dives.

Dive 1: 30metres for 15minutes, followed by a 45minute surface interval resulting in pressure group D.

Dive 2: 25metres for 17minutes, followed by a 50minute surface interval resulting in pressure group G.

Dive 3: 20metres for 15minutes ending in pressure group P.

The final pressure group and required number of safety stops after completing this series of dives is PG P with 2 Safety Stops.