Is there a DCI lag time?

[wedivebc]

I was told years ago by a physiologist who worked for the U.S. Navy that the Navy deco tables have a 1+% bend rate. This Surface Deco procedures was the cause of it in his opinion. When I asked why they did this, he replied that an entire ship may be in harms way "waiting" on a diver to finish in-water deco. This was militarily unacceptable. The diver is designed to take the "risk" not the entire ship.

I believe the navy has extreme exposure tables that have the higher risk you mention but I don't believe that is the norm. I am not a navy diver so I can't say for sure though.

 

[ranger]

I just checked my Navy Divers Handbook and when performing Sur D on air there is no reference to how quickly the tenders must undress the diver and have him in the chamber. But when performing Sur D on O2 the handbook states the tenders must have the diver undressed and in the chamber in 3 1/2 minutes.

 

[BigJetDriver]

Ranger,

Thanks for looking that up!

 

[Heffey]

30 mins to 12 hours, if i remember correctly. And yes, it was treating DCS. If he had wanted to prevent it, he would have done that underwater, via deco stops.

I suppose in theory he could have been doing a dry decompression, but thats a commerical/military thing.

On this TV program I have seen them do some staged deco stops and a few of these run for the chamber deco’s. I never saw anything that would make me suspect that this chamber dash was not a planned part of the dive.

 

[Dr Deco]

Hello readers:

Surface Decompression

This is indeed an established method of decompression. Divers will hang quietly, on air, at the 30-foot stop [defined in the Sur-D O2 Tables]. In many cases, a direct ascent to the surface is possible [no stops are made in the water] and all of the decompression duration is accomplished in the chamber while breathing oxygen.

The time from the ascent while in water [stop or no stop] to the chamber must not exceed 5 minutes according to the USN Diving Manual.

There are also decompression procedures to complete the deco in a chamber while breathing air [Sur D Air]. The ascent is made from a 10-foot top in this case.

How It Works

As I have said on many occasions over the last five years, there is a period of time during which dissolved nitrogen diffuses into micronuclei. This is not an instantaneous process. While the nitrogen diffuses and the bubbles grow, you can enter the chamber and be recompressed. Certainly there is an upper limit (five minutes) to this. I might add that I would caution against lifting, running or straining while in that surface interval.

Dr Deco :doctor:

 

[Heffey]

Hello readers:

Surface Decompression

This is indeed an established method of decompression. Divers will hang quietly, on air, at the 30-foot stop [defined in the Sur-D O2 Tables]. In many cases, a direct ascent to the surface is possible [no stops are made in the water] and all of the decompression duration is accomplished in the chamber while breathing oxygen.

The time from the ascent while in water [stop or no stop] to the chamber must not exceed 5 minutes according to the USN Diving Manual.

There are also decompression procedures to complete the deco in a chamber while breathing air [Sur D Air]. The ascent is made from a 10-foot top in this case.

How It Works

As I have said on many occasions over the last five years, there is a period of time during which dissolved nitrogen diffuses into micronuclei. This is not an instantaneous process. While the nitrogen diffuses and the bubbles grow, you can enter the chamber and be recompressed. Certainly there is an upper limit (five minutes) to this. I might add that I would caution against lifting, running or straining while in that surface interval.

Dr Deco :doctor:

Thanks Dr Deco,
I really appreciate you taking the time to explain this.
It makes much more sense to me now.
It still seems a bit risky.
Miles away from rec diving I suppose.
Thanks again,
Jeffrey