Grab your RDP or eRDPml and check out the special rules and considerations printed on the back or inside the lid.

The W and X rule states that they must have a 1 hour surface interval and the Y and Z rule is 3 hours.

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Tidal Volume is the volume of air that is involved in inhalation and exhalation within the lungs. 

Everything that is inhaled into the upper airway that has no part of that is called Dead Air.


This is covered in the Paperwork and Administrative Procedures section of the PADI Instructor Manual. Remember this section is alphabetical so that should help with searching for it listed under Quizzes and Exams.

As light waves travel through mediums of varying density such as air and water they bend at the interface of the differing mediums. 

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Three friends; Emily, Joe, and Karen are completing their Open Water Diver Course together. The group complete all of their confined session and Dive 1 together but Joe feels seasick prior to Open Water Dive 2 and sits it out and the Instructor, Si completes Dive 2 with Karen and Emily.

The group would like to continue the course together but cannot extend their stay and ask Si what they can do to make the most out of their remaining time.

Si tells them that Joe may complete Dive 2 while Karen and Emily complete the performance requirements for Dive 3 on the same dive as long as they all stay within the maximum depth of 12 metres.

Then the last day of their stay Karen and Emily will be able to complete Dive to a maximum depth of 18 metres but Joe wouldn’t be able to join and leave with his PADI Scuba Diver certification.

Is Si meeting PADI standards and is he making the correct decision?

Si is employing a technique called ‘Multiple –Level Teaching’ Having students from varying levels conducting different performance requirements while limiting them all to the most conservative depth limits.

As long as all objectives and supervision requirements are met he’s come up with a good solution for his students.

He could also offer Joe a referral for the diving that he has completed but this is only valid for one year. The Scuba Diver certification may be the preferred option if Joe doesn’t know when he’ll have the opportunity to complete the balance of the PADI Open Water Diver Course.