View Full Version : Experimental Tables for Freediving

Capt Nemo
10-07-2012, 01:01 PM
I found this awhile back on Deeper Blue.

One doesn't think that decompression sickness (DCS) could affect freedivers, but it does! Freedivers do breathe compressed air same as scuba divers, due to Boyle's Law naturally compressing the air in the divers lungs. This forces nitrogen into the bloodstream and tissues. The faster ascent rates of freediving can trigger DCS, as the body does not have time required to release the nitrogen built up. Repetative dives worsen the problem of nitrogen buildup.

One freediver began running standard freediving practice thru the DSAT algorithm used on dive computers. Here's the table that it came up with.


This table shows how many dives can be made to a given depth/bottom time given normal freediving practices. Do remember that this table has not been fully checked for accuracy, but it can serve as a guideline to help prevent a DCS incident. Most of us are probably not going to get anywhere near these limits.

10-07-2012, 10:38 PM
Wow, thanks for sharing. I had no idea that freedivers needed to be worry about DCS.

Capt Nemo
10-08-2012, 12:37 AM
It's becomming a problem along with lung squeeze on deep dives. A number of spearos have gotten bent as they're going deeper to find the big ones. An afternoon of spearing could easily put most of them into a DCS situation when they're hitting 100+ feet. From the chart, (100' = 30m) at 100' they could do 15 one minute dives with 6 minute surface intervals. That's not much diving!

In the 10m area where we operate, most of us would only be doing 1-2 minutes, and by the chart, we can do 100+ dives without worry.