Decompression Procedures

Technical diving requires carefully planned and executed decompression stops in order to safely push the physical limits of scuba diving. This is true TEAM DIVING.

The longer our bodies spend at depth, the more high-pressure nitrogen dissolves into our blood and body tissues. The deeper we go, the faster the nitrogen accumulates. In order to safely release the dissolved nitrogen from our bodies, we must ascent at a slow, controlled rate and stop at predetermined depths for scheduled lengths of time. These stops are known as decompression stops and are mandatory in tec diving.

Since decompression can be really long and boring (not to mention strenuous on the body), we bring along EANx50 (50% O2 / 50% N2) and 100% O2 decompression cylinders to accelerate decompression stops. By increasing the partial pressure of oxygen in our breathing gas, we can off-gas more nitrogen safely and therefore end our dive sooner.

We have to be extremely careful when switching gasses, as breathing the wrong mix too deep can be fatal. For EANx50, the max depth is 21m/70ft; for 100% O2, it's a mere 6m/20ft!!

Our TDI Extended Range dive to the second hole at Hole in the Wall on Roatan, Honduras, lasted just 17 minutes at the max depth of 55m/180ft, but required 37 minutes of decompression stops using mixed gases to safely return. Our decompression schedule was:

30m/100ft - 1:00
27m/90ft - 1:00
24m/80ft - 2:00
21m/70ft - 4:00 --> Switch to EANx50 for decompression
18m/60ft - 1:00
15m/50ft - 2:00
12m/40ft - 3:00
9m/30ft - 6:00
6m/20ft - 2:00 --> Switch to 100% O2 for decompression
5m/15ft - 11:00

Overall, this enabled us to do a deep dive to 55m/180ft for 17 minutes at depth and complete the entire dive in under an hour!

Read more about this tec dive to Hole in the Wall (#2214)

Photo by Alex Harper-Graham of Roatan Tec Center

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