Decompression diving

[Thrillhouse]

I recently spoke with someone who's started decompression diving and says it's really interesting. We only talked briefly, but it got me to wondering what deep diving (decompression) is all about, and what there is to see down there? I know geographic regions can be enormously different in what varieties of life they offer, but what are the attractions for people diving beneath 140ft, other than particular things like wrecks? For people that do this sort of diving, is there anything in your part of the world that's only found farther down, and if so, what is it?

Just curious about the whole matter... Sounds really interesting. Also, what are the conditions like in your experiences?

 

[oly5050user]

you can get into a decompression dive alot shallower than the 140 ' you wrote about..every dive,if you look at it in theory , is a decompression dive.Where you do your decompression (in water or out of water during surface interval)makes the difference.

 

[Blackwood]

The application of decompression isn't all that interesting. It's simply a tool, a means to an end. That end may be (safely surfacing from) deep sites or shallower sites that you want to spend a reasonable amount of time on.

Here's a short story about our most recent dive on the wreck of the Palawan (relatively shallow average depth of about 100FSW) here in Redondo Beach.

Our team hit the surface after dive 1 just as a couple or divers on a different boat were making their descent. In the time it took us to swim to the stern, hand up our O₂ bottles, climb on board and get out of our gear, the other two divers had surfaced from their dive. To me, that's hardly worth the effort, let alone the cost of fuel.

Where you do your decompression... makes the difference.

And for how long.

 

[crpntr133]

I didn't do deco class to solely go deep. There are many things that I want to see that are in the 100' range. With deco it gives me more time. Yes, there are those that are 130-140 range but they are few.

 

[brockbr]

The application of decompression isn't all that interesting.

Ouch Blackwood - It hurts me to see you write that

...I think it's interesting. <sulks off...>

 

[RonFrank]

Deco diving does two things:

1) More time at rec depths
2) Some time at non-rec depths.

If I wanted to spend I lot more time at depth, I'd consider getting Close Circuit certified.

Nitrox can go a long way towards spending more time at depth. At 100' EAN 36 provides 40 minutes of dive time vs. 25 minutes on air.

 

[Peter Guy]

OP -- close to your home is a great reason for deco diving -- the Cloud Sponges in Saanich Inlet and elsewhere. Since they don't start until around 100' -- in order to actually spend enough time to make it really fun, you WILL go into mandatory decompression (that is, unless you really want to push your PPO2 levels!).

Cloud Sponge at 120':

 

[Blackwood]

Ouch Blackwood - It hurts me to see you write that

...I think it's interesting. <sulks off...>

I personally find decompression theory and planning pretty fascinating.

But ascending and sticking a reg in your mouth, not so much.

BTW, 1.2 is looking good. Can't wait for the VPM update!

 

[Jorgy]

oly5050user had it right......you can go into deco much shallower than 140 feet.....

Let me provide the detail for one of my 7 deco experiences......

3rd day of diving on air in Cancun, 37 minutes into the 2nd dive of the day, my Suunto went into deco at 49 feet......the dives......

Dive # Length Max Ft Avg FT SI Where
1 41 min 46 ft 28 ft > 24 h Cenote
2 35 min 43 ft 23 ft 11 min Cenote
3 37 min 92 ft 51 ft 22 h Coz
4 48 min 42 ft 34 ft 36 min Coz
5 42 min 52 ft 43 ft 21 h Cancun
6 46 min 53 ft 45 ft 38 min Cancun

Fortunately, we were back at the boat, so I simply cleared the 5 minute deco obligation on my safety stop.

When you dive the reefs near Cancun you end up with a vary square profile as the reef is short only about 6 to 7 feet tall along the bottom, so the entire dive is at 50 feet.

In looking at the data in the table, I will admit that the SIs for dives 4 and 6 were short, a longer 1 hour plus SI would have been more prudent. Hindsite is always 20/20.......

Another point, Suunto's are known as conservative and don't provide max bottom time, so my deco obligation may just have been an artifact if the computer, but since that is what I dive, I made sure the obligation was cleared before I surfaced.

Hope this helps......M

 

[Tortuga68]

I too find the theory & planning of deco diving fascinating - not at all boring! Then again I'm pretty new to it

...what there is to see down there? I know geographic regions can be enormously different in what varieties of life they offer, but what are the attractions for people diving beneath 140ft, other than particular things like wrecks? For people that do this sort of diving, is there anything in your part of the world that's only found farther down, and if so, what is it?

Just curious about the whole matter... Sounds really interesting. Also, what are the conditions like in your experiences?

As you said, wrecks are often in deeper water... there are also lots of reef walls that go down 90+ metres, different forms of life at depth compared to shallower waters etc

As far as conditions go, obviously deeper can mean colder and darker, and you will get noticeable symtoms of narcosis - all part of the 'fun'

But as previous posters have noted, it's not just about going deep