Lesson 134

Lesson five: Missing a Decompression Stops

Course Complete

Learning Objectives

By the end of this session, I should be able to answer these questions:

1. When do I need to make an emergency decompression stop?

2. How do I determine the depth(s) and time(s) of emergency decompression stop(s)?

3. What should I do if I surface from a dive without making a required emergency decompression stop?

Emergency Decompression Stops

In Section Four, you learned that if you exceed a no stop limit, you will have to make one or more emergency decompression stops. Unlike safety stops, emergency decompression stops are required so that you don’t exceed accepted theoretical nitrogen levels. Safety stops keep you well within limits, whereas emergency decompression stops return you from outside limits.

In recreational diving, required emergency decompression stops are emergency situations only. They mean you either failed to monitor your dive computer (or timer and depth gauge), or something forced you to overstay your time at depth. Failure to monitor your instruments doesn’t have to happen (it’s your responsibility). Circumstances that keep you from starting your ascent are exceptionally rare.

In recreational diving, emergency decompression usually results in one required stop. More than one required decompression stop would be highly unlikely, but it could happen if a diver were to significantly exceed no stop limits

Emergency Decompression Stop Depths and Times

If you exceed your computer’s no stop times, it will go into decompression mode. Decompression mode guides you by providing the depth of your emergency decompression stop and how long you have to stay there before you can ascend to the surface (or the next stop if there is more than one). Don’t ascend above the stop depth. You may be slightly deeper, however.

Computers differ in how they display emergency decompression information. See the manufacturer literature for the details of yours. You can find the RDP Table and eRDPML emergency decompression procedures printed on each and in their Instructions for Use guides.

Missing a Required Decompression Stop

If you don’t have enough air to complete an emergency decompression stop, stop as long as you can, but save enough air to surface and exit safely. This is an emergency, but don’t run out of air underwater trying to make the stop.

If you didn’t complete the entire emergency decompression stop (or accidentally skipped it altogether), after ascending, relax, breathe 100 percent emergency oxygen if available and monitor yourself for decompression sickness symptoms. Don’t dive again for at least 24 hours. Many dive computers will go into an error mode and lock up, not allowing a dive for that long or longer.