Diving without computers

[NAM001]

A safety stop is a preventive action. a mandatory stop is a corrective action.
Skip a safety and no foul to 99.9% skip a mandatory and its flirting with a chamber trip.

Mandatory safety is still a safety. talk earlier of GF100 is a good explainatioin in my book. If you push the GF. you need to take some safety time to distance your self from the 100 mark to avoid POTENTIAL problems if enough other factors are against you.

No rec dive should ever be a problem needing a stop. NO DIVE DONE CORRECTLY!!!!!!!!. Now in case you ascend too quickly your safety margin gets smaller and you make up for it/ enlarge it/get it back at the safety stop. After all,,, how much talk has been done about 60 vs 30 ft per minute ascent rate. The more you push the actual NDL the more you deminish the safety factor and may need the safety stop to get it back. Right or not,,, i look at it as the last 20 ft is the most critical depth change of the dive and your body has to be prepared for it. Most dives have sufficient margin in it to go directly to the surface with no foul. push the limits too much and the last 20 ft can get you. Once again dive limits OW <60' maximizes the safety factor for new divers so the skills , no matter how poor, does not cause a health problem by insuring the greatest internal safety margin available allowed by the dive.

Now so many people push the limits of the dive to get the most for their boat dive trip bucks. Add a deep dive to the package, add a long dive to the package, add 4 dives a day, and the safety margin gets much smaller.

How many have ever been asked which computer lets you stay down the longest??? Those folks are well advised to never skip a safety stop.

Jeff Foxworthy would say "You might need to do a safety stop if your computer lets you stay down longer than all the rest."
You might need to do a safety stop if your computer allows you to do deep ascents at a gagilliion ' /min.

The list can go on.

Along with the new divers. Not much happens when you have a line to climb up. AS new diver trying to hold 20 ft in a sea state from a deep dive forfiets a lot of safety margin.

So padi and computers now recommend MANDATORY safety stops when going deep or pushing the NDL envelope.

 

[doctormike]

So padi and computers now recommend MANDATORY safety stops when going deep of pushing the NDL envelope.

This is a non-sequitur. A stop is either recommended or mandatory. My understanding of the definition of "safety stop" is an optional stop added to every dive over a certain shallow depth, regardless of profile. I have no idea what the term "mandatory safety stop" is supposed to mean.

Of course, the computer can't force you to do anything, but a mandatory stop means that the model predicts an increased likelihood of DCS if you don't do it. This is true whether the stop is generated as part of a planned staged ascent after going over NDL, or if it's generated based on some other parameter like an ascent rate violation. That's physiology. The rest is semantics.

 

[NAM001]

This is a non-sequitur. A stop is either recommended or mandatory. My understanding of the definition of "safety stop" is an optional stop added to every dive over a certain shallow depth, regardless of profile. I have no idea what the term "mandatory safety stop" is supposed to mean.

Of course, the computer can't force you to do anything, but a mandatory stop means that the model predicts an increased likelihood of DCS if you don't do it. This is true whether the stop is generated as part of a planned staged ascent after going over NDL, or if it's generated based on some other parameter like an ascent rate violation. That's physiology. The rest is semantics.

I agree with your understanding. Many of us have share it. Ive heard it explained as ....a safety stop is something you can skip if you need to, UNLESS you are with in 10% of NDL or the dive was greater than 60' then it it is required. But the requiremnt is not from a need to do a deco procedure but from a elevented level of prevention standpoint. Ive had divers tell me that the 3 min stop is required for those reasons. It all stems from the language used in the classes. And language will never be something that everyone will be in agreement with. Human nature always kicks in.

When I started in the 60's 60 fpm was the rule to TRY to keep. now its 30 fpm. Human nature kicks in and says if 30 is really the rule how did I make it this far using 60 ????? And we file it under organizational CYA. I would prefer recommended and strongly recommended safety stop language instead of mandatory safety stop.

 

[Bubblesong]

actually, we could have a whole gradient of safety stops, Optional, Recommended, Optimal, Crucial, Required, Mandatory and Might-as well-call-the-chopper-now-Obligation.

 

[NAM001]

actually, we could have a whole gradient of safety stops, Optional, Recommended, Optimal, Crucial, Required, Mandatory and Might-as well-call-the-chopper-now-Obligation.

Funny response but true. I have never considered it a problem. But then I know nothing is perfect and plan for it.
Yep and the patient dies from the cure rather than the desease.

 

[doctormike]

I agree with your understanding. Many of us have share it. Ive heard it explained as ....a safety stop is something you can skip if you need to, UNLESS you are with in 10% of NDL or the dive was greater than 60' then it it is required. But the requiremnt is not from a need to do a deco procedure but from a elevented level of prevention standpoint. Ive had divers tell me that the 3 min stop is required for those reasons. It all stems from the language used in the classes. And language will never be something that everyone will be in agreement with. Human nature always kicks in.

When I started in the 60's 60 fpm was the rule to TRY to keep. now its 30 fpm. Human nature kicks in and says if 30 is really the rule how did I make it this far using 60 ????? And we file it under organizational CYA. I would prefer recommended and strongly recommended safety stop language instead of mandatory safety stop.

Exactly, and I agree that this really comes down to language. Both decompression stops on a dive over NDL and required stops on a dive within NDLs do the same thing - they allow for safer offgassing and minimize the chance of DCS. Safety stops are something that are recommended based on the policies of a training agency or a computer manufacturer and are not dive-specific.

I guess the best thing to do would be to avoid the term "required safety stop", and come up for a word that means "stop that you need to do based on your profile or you are more likely to get bent".

 

[boulderjohn]

a safety stop is something you can skip if you need to, UNLESS you are with in 10% of NDL or the dive was greater than 60' then it it is required.

Whose rules are those?

 

[drbill]

Back when I did my first dive in the early 60s there were no dive computers (or PCs to download them to) not to mention octopus, SPG, BCD, etc. In my first few decades I dove without most of those, but generally was doing no more than 2 dives in a given day. That changed in 2000 when I started doing a lot more dives. I got my first dive (an Orca Skinny Dipper) back in the late 1990s and my second in 2001. Today I wouldn't dive without one... in fact I use two for redundancy. But then in the recent past I've done as many as 350 dives a year and 7 dives in a day.

Another reason I wouldn't dive without a computer is that I often make dive trips to areas without nearby chambers. The computer gives me a much more accurate way of either staying out of deco or managing it when I do. In remote destinations that just makes more sense to me than risking a possible DCS hit with a chamber many miles away..

 

[NAM001]

Whose rules are those?

I know you probably dont like the word rule but that is the way it has always been. its even taught that way in OW. Safety stop is just that. a little blanket of safety not always needed unlike a mandatory stop that is needed. And i think they still talk about 3 min safety stop (still optional) and up to 5 minutes under some conditions, Even the 3&5 in is still not required but recommended.

 

[doctormike]

I know you probably dont like the word rule but that is the way it has always been. its even taught that way in OW. Safety stop is just that. a little blanket of safety not always needed unlike a mandatory stop that is needed. And i think they still talk about 3 min safety stop (still optional) and up to 5 minutes under some conditions, Even the 3&5 in is still not required but recommended.

Actually I'm a bit confused about that too - the 10% of NDL or greater than 60 feet rules. Are those from some agency?

I mean, if the rule says that with X amount of N2 loading (defined as being within 10% of NDL) you generate an ascent profile that includes a mandatory 3 minute stop at 15 feet, that's a deco stop. The NDL is calculated by the algorithm, so it's model-dependent to say that you are within or past NDLs anyway at any given point.