Tuesday, August 16, 2005

Deep safety stops

Last year while diving with some divers from all over the country, we discussed various safety stop strategies. Of course we were very strict in keeping to our three minute safety stops at 15 feet.

Personally, I do not view the safety stop as a waste of time. It is a time of reflection on the dive, and also a time when I can practice buoyancy control and various other skills. I need to keep sharp on my skills and use this time as extra practice time (for example mask clears etc).

One technique we discussed and which I have became very interested in, is making additional deep safety stops. There are a number of ways to do the deep safety stops. One method is to make one minute safety stops at 50% of the depth, then 25% and finally three minutes at 15 feet. For example if your dive to 100 feet, then you will do a safety stop at 50 feet, 25 feet, and the usual 15 feet. Some people even will do a further short safety stop at 7.5 feet.

Another method would be to make a deep safety stop at 50% depth for 1 minute and then a 2 minute stop at 15 feet. However, I think that a 2 minute safety stop at 15 feet is too short, but there is a research project underway to test this theory (see website mentioned below).

There is an interesting article about deep safety stops at the DAN website The authors delve into a fair amount of history and theory but it is worth reading.

Interestingly, the 60 feet per minute ascent rate seems to be on the high side. It would seem that the more prudent ascent rate would be less than 30 feet a minute. From the DAN article, it seems that 60 feet a minute was decided without too much scientific evidence and research.

In case anyone might misunderstand - please ascend NO FASTER than 60 feet per minute (the slower the better) and ALWAYS make a 3 minute safety stop at 15 feet (air supply permitted of course).

1 comment:

Willy Volk said...

Interesting post. When diving, I often see people rush to the safety stop, as though they're in a race. I try to chill out for a minute about every 10 feet, like my friend Bill Reals suggests (http://www.divester.com/2005/07/28/tips-for-making-deco-dives/). Sometimes that's tough, but it's much better than the alternative.