Light deco?

[scubadada]

As a corollary to a recent post/poll regarding advancing from recreational to technical diving Happy to always dive advanced within recreational limits, forever ? [Poll], I would like to know if you use the term light deco. If you do, I would appreciate it if you would supply your definition for the term.

Good diving, Craig

 

[Stoo]

All the time. I also refer to a lot of the diving I do as "Tecreational". Flap around on a 110' wreck, but wearing doubles and slinging a 40 of 100% O2. These dives are deep enough that a diver hits the NDL very quickly. They also tend to be square profiles, so it's not like we can work our way up to a shallow reef to avoid a deco obligation. If I'm going to go to all the effort of getting to the site, I want to stay longer than 12 minutes.

It's not unusual to rack up some deco... say up to 10 minutes... and use the O2 to minimize that time.

 

[Vicko]

All the time. I also refer to a lot of the diving I do as "Tecreational". Flap around on a 110' wreck, but wearing doubles and slinging a 40 of 100% O2. These dives are deep enough that a diver hits the NDL very quickly. They also tend to be square profiles, so it's not like we can work our way up to a shallow reef to avoid a deco obligation. If I'm going to go to all the effort of getting to the site, I want to stay longer than 12 minutes.

It's not unusual to rack up some deco... say up to 10 minutes... and use the O2 to minimize that time.

What part of that staged accelerated deco dive is rec?

I do light deco on most of my dives, i consider it any dive where my only plan is leaving the water with 30 bars in my tank and i leave the no deco limits.

 

[Johnoly]

.. the term light deco.

I do but I think it's different than all the others. I HATE deco >> If you sit thru the DAN presentations at DEMA every year on bubble technology it is just a huge eye opener on the potential damage stuck micro bubbles can have on tissue (yaa I know zillions do deco with no harm, just my preference not to).

On those dives I'm digging a fish or bug out from under a deep hole/ledge on my 3rd dive, rarely I'll ...turn on my deco light...on my Pro + 2. It almost always clears as I start to ascend and by the time I hit my 20ft stop it has turned off.
That's my definition of light deco or turning on my deco light. YMMV

 

[northernone]

If I do talk of light deco (rarely do) I'm meaning a deco obligation which might not be rapidly debilitating or immediately fatal if blown off. Pretty much deco that's only an extended safety stop according to the most liberal dive tables.

For example:

If I do 10 minutes deco on a conservative setting with Bühlmann algorithm and a gf of 60/60 , I'm doing light deco. A Cochran computer wouldn't blink and USN tables would show I could safely ascend directly with no stops.

 

[Stoo]

What part of that staged accelerated deco dive is rec?

None. Hence "Tecreational". I also don't really subscribe to the concept of rec and tec being totally separate "sports". That's largely a reflection of the PADIfication of diving... create a separate course/category for every new skill. Back in the day, more advanced diving logically moved into decompression diving.

This is not to make light of the the consequences of botched decompression dives. All I mean is that moving from no-deco-never-stray-past-the-NDL to a little staged deco is just a continuum, and easily managed by a competent, knowlegeable diver.

 

[tbone1004]

similar to @northernone
If I can complete the dive as NDL if I set my computer GF to 100/100, then it's "light deco". Essentially an extended safety stop. That usually comes out to less than 15 minutes of backgas deco with the GF's that I normally run.
Anything more than that, and you are going to use accelerated deco gases and you can't head up to the surface without breaking the 100/100 line.

 

[boulderjohn]

I chose "no" because the term has no accepted definition, and I don't like to use terms that can be misunderstood.

Posts #5 and #7 each describe something I do, but when I posted something like that a couple years ago, one guy in particular tried to bring the wrath of the SB community down on my head. I usually do my tech diving with my GFs set to 50/80, and I usually don't bother changing that when I do a single tank recreational dive. (I don't even know what it looks like to put my computer into recreational mode.) As a consequence, I will go into deco before anyone else, but if I am diving with friends with typical recreational computers, my deco will often clear and allow me to go to the surface before their 3-minute safety stop counter is done. I consider the "deco" I do on that dive to be a mere technicality. I know enough about decompression to know when it is serious. This past May I did 3 weeks of recreational diving in Palau. I simply changed the GFs on the computer and never had to deal with that.

Things start to get serious when there is a concern that having to blow off that deco because of a gas loss or other problem will increase the DCS danger more than a minute or two past the pretty-darn-safe level of a safety stop. In that case, I need to have at least redundant gas. If I have redundant gas, I'm good for a while longer, with "a while longer" determined by the amount of each gas remaining.

We are always playing the odds when we dive. Stay within all limits on a recreational dive and the odds are very, very much in your favor. Go to the edge of NDLs, and the odds start to tilt against you. Go beyond NDLs by a few minutes and they have tilted some more. Go beyond a couple of minutes without redundant gas, and you have added another risk factor. People will argue that having a catastrophic gas loss at the tail end of a dive like that is highly unlikely, but it is still an added risk factor. As you add risk, there will come a time when that level of risk starts to get foolish.

Last winter I encountered a recreational diver who routinely racked up 10 minutes of deco with no redundant gas. That is more than I would be willing to do.

 

[kensuf]

Anything less than 10 minutes of back-gas deco is what I would consider "light deco."

I also think that with several social media posts showing computer profiles (and I have been guilty of this myself), we need to regularly remind ourselves of what the US Navy considers an "exceptional exposure" dive and show dives that require staged decompression with the respect they are due. The USN definition can be found on page 9-30 under section 9-10. https://www.navsea.navy.mil/Portals...ING MANUAL_REV7.pdf?ver=2017-01-11-102354-393

 

[JohnnyC]

My personal definition aligns with Ken's. In which case, occasionally, I'll do light deco.