Beyond 130 feet: always a deco dive?

[Rhone Man]

I have done dives with max depths in the 145 ft range without deco, but it is a pretty rare beast.

As others have noted, in days of old when men were bold and US Navy tables were all we had, you could go to 200 ft without a deco obligation, but that is not recommended these days, and you would be hard pushed to find a deco planner or dive computer which agreed with the US Navy.

 

[DevonDiver]

Even the limits change over time and to some extent between agencies. If youve used 1.6/1.8 for 20 years, will you lower it to 1.4/1.6 because the agency youre with change their standards?
(Outside of a training setting that is)

As an instructor, I practice what I preach. Credibility and role-modelling. Having said that, several of the agencies I teach for have different policies on max PPO2... so it depends what hat I am wearing...

I used to have a very 'free-spirited' attitude towards PPO2 - mostly in respect of deep air diving. I grew older and wiser.

 

[pasley]

Just wondering about this: if you dive with a computer to beyond 130 feet, will you ALWAYS be in a decompression situation? Well, I guess that's worded badly. Let's try this: "recreational divers plan all dives to be no stop dives". Does that mean that beyond 130 feet, you will always have to do a stop, and therefore be tech diving and not recreational diving? (I use 130 feet because it seems to be the max depths of most agencies, but I often see posts of people talking about going deeper, and I'm wondering if they are tech diving or just recreational divers who know how to do a safety stop?)

This is your original post. Your profile list your dives at 25-49 which is not brand new, but in the range of still a newer diver. So you will forgive us if we think it does read like:

...The question I did NOT ask was:"LAWLZ! I am teh OW certified this weekendz, guyz can I go to 200 ft? Do u thnk I need a wetsuit?"

Your clarificaton of your intended question is below:

WHY do some divers who are only trained recreationally go deeper than 130 feet?

This in IMHO quite a bit diffent from the original question.

I realize now from the answers that the answer is "because they are being foolish and trying to push their limits".

Your analysis is IMHO correct. Another way of saying it is "because they are in the running for Darwin Awards and not someone I should have as a dive buddy".

 

[mstachowsky]

Yes, I realize that my first question and my clarification were different, sorry about that. Thanks for the replies!

MIKE

 

[shoredivr]

Mike, don't backpedal now, your second reply was priceless.

 

[mstachowsky]

haha well I just wanted to be clear that I wasn't trying to ask a stupid question

 

[DevonDiver]

As others have noted, in days of old when men were bold and US Navy tables were all we had, you could go to 200 ft without a deco obligation, but that is not recommended these days, and you would be hard pushed to find a deco planner or dive computer which agreed with the US Navy.

I'm guessing the US Navy also has regulations/procedures that entail rapid access to a hyperbaric/recompression chamber, along with stipulations about fitness, health, currency of training and access to medical/emergency treatment/first aid etc.

Basically... a whole support network structured to prevent medical complications from the pursuit of a military goal underwater - a mission that, under some circumstances, may take priority over the immediate safety of the diver.

I also believe that statistically, the incidence of DCS has decreased markedly per decade, dispite a rapid swelling in diver population/activity and an (alleged) dumbing down of recreational scuba training standards.

Comparing military with leisure diving is chalk-and-cheese. To a lesser degree, comparing the 'old and bold' pioneer diver with the typical resort diver is also a chalky-cheezy situation...

 

[dpaustex]

I would suggest you all pull your old dive books out and understand WHY there are issues below the 130 foot range.

For starters, look at gas laws. Oxygen toxicity starts to become an issue, as well as narcosis. That is why tech divers use inert gasses in their mix.

You all should take a Nitrox course, which will go into partial pressures in more depth, and discuss the above items.

It is a bit frightening that people on here think their fancy computer is going to solve the problem for them, without understanding gas laws and impact on the body. These are the same type of people that will penetrate a wreck, just because they purchased a $30 reel spool.

An OW card is a beginning level card. I tell folks it's realistically good to about 60 feet. Any deeper than that, and you really should get more training (deep diving class, for starters). Gear issues come into play, too, the deeper you go.

Tread carefully, and don't think reading stuff online qualifies you to endanger you and your dive buddy.

 

[ianr33]

I would suggest you all pull your old dive books out and understand WHY there are issues below the 130 foot range.

For starters, look at gas laws. Oxygen toxicity starts to become an issue,

I don't worry too much about oxygen toxicity diving air to 150, but that might just be me................

 

[boulderjohn]

The old Navy tables, using a system that is often called "bend and treat" among technical divers, did require a brief stop after a 5 minute bottom time at 200 feet, but not at 190 feet. Remember that bottom time includes the descent, so if you are descending at about 60 fpm, you really have 2 minutes of true bottom time. What would be the purpose of such a dive, other than to say you did it?

As Flotsam pointed out, modern dive programs don't agree with the old Navy tables at all, and they will require much more extensive decompression.

Narcosis is nothing to sneeze at. If you were following a very major ScubaBoard thread about a year ago, you will remember the 3 divers in Cozumel who wanted to do such a dive to 300 feet, just to say they did it. One of them suffered enough narcosis that she blew past the 300 foot planned depth and was finally caught by one of the others at 400 feet. They ascended quickly, running out of air at about 200 feet. The third diver had stayed more shallow, and he had enough gas to get all 3 to the surface with 3 person buddy breathing. By staying shallow he also managed to come out OK. The narked diver died, and the other is paralyzed.

Or you can get the training and do deep dives safely with enough bottom time to do something meaningful.