Quiz - Recreational Dive Planner™ - Pressure Group

[Pedro Burrito]

From the Recreational Dive Planner section of the PADI Dive Theory Exam. You will need your RDP™ to answer this question.

What is a diver's pressure group after surfacing from a dive to 9 metres / 29 feet for 77 minutes?

a. O

b. P

c. N

d. M


I will post a daily question from my exams to help newer divers and to encourage more experienced divers to interact gracefully and helpfully with the newer divers.

Reminder - this is a post in the Basic Forum and it is a green zone. Please be nice and on topic.

 

[Jcp2]

I think the latest instruction is “whatever the dive computer says is better than the dive tables”, so the answer is E. None of the above.

 

[HKGuns]

But but but the dive tables start at 35 feet............................

 

[kmarks]

This is very dependent on which table you are using.

The SSI recreational dive tables only go from Groups A-K. A dive to 29 feet (round up to 30) for 77 minutes (round up to 95) would put you in group F.

 

[tursiops]

But but but the dive tables start at 35 feet............................

Spoiler

Right...cool question! You always use the next greater depth on the table....so you use 35. It is a litle easier in metric...the RDP starts at 10m.

 

[scubadada]

This is very dependent on which table you are using.

The SSI recreational dive tables only go from Groups A-K. A dive to 29 feet (round up to 30) for 77 minutes (round up to 95) would put you in group F.

From the Recreational Dive Planner section of the PADI Dive Theory Exam. You will need your RDP to answer this question.

 

[tursiops]

This is very dependent on which table you are using.

The SSI recreational dive tables only go from Groups A-K. A dive to 29 feet (round up to 30) for 77 minutes (round up to 95) would put you in group F.

Spoiler

This is a good learning question. The question, of course, is based on the PADI RDP. The SSI tables, like the NAUI tables they are based on, only use the first half of the alphabet for the NDL pressure groups; the second half is reserved for going beyond NDL, into deco. That means the SSI/Navy pressure groups are larger than the PADI groups, and the groups from the PADI and SSI tables cannot be used interchangeably. Getting smaller pressure groups, for a finer resolution in off-gassing times, was one of the reasons for the development of the RDP.

 

[HKGuns]

Spoiler

Right...cool question! You always use the next greater depth on the table....so you use 35. It is a litle easier in metric...the RDP starts at 10m.

That is what I was trained to do and what I did!

 

[kmarks]

SSI/Navy pressure groups are larger than the PADI groups, and the groups from the PADI and SSI tables cannot be used interchangeably.

Obviously.

The SSI tables are also adjusted from the navy pressure groups to make them slightly more conservative. But I think the real answer in this case is jcp2 says because open water training in both PADI and SSI only teaches tables as a curiosity and not as a tool to be used. I did my OW training with PADI and we were given a computer supplement and told to ignore the section in the training manual on the RDP (in 2013). I'm now an SSI DM and we do actually briefly teach the tables and how to use them in OW classes, but also suggest that every student purchase their own computer and use that. I personally use the tables for very limited planning ("If I go to 105 feet to see that wheelhouse, how long will I have? Oh, 15 minutes, ok.") but once in the water, I rely on the computer.

 

[CT-Rich]

The question needs to be edited to statE “according to the PADI dive tables”. I have never done anything with PADI. I have used Navy tables, NAUI and SSI, I was wondering WTF did they get these letter designations from. When I used the SSI table, it came out as an F group.

Once I looked up the correct table, I got it right.