Decompression Diving

[lamont]

If you're gonna do this, at least download v-planner (the crippleware version of it works for any gas mixture with less than 50% O2) and stop using the Navy tables.

Of course you should take classes, and you should register v-planner. But at least you're not using an outdated algorithm if you use v-planner.

 

[brycegroark]

Wow. Thanks for all the responses. I have no formal training on decompression diving, actually - which seems to be the norm of all your responses. I have over 3000 dives, truly feel like I know what I am doing (in the least arrogant sense) but was nervous about the possible long term effects. I follow my computer - not any dive tables - for all my dives, which may be another problem in itself, according to some.

I also have been diving this way for more than a year now and have had no adverse effects ever (sometimes a bit exausted at the end of the day). I feel like some of the responses are a little extreme - especially since I always finish my deco stops and usually do multiple minutes more before ascending. My Suunto computer is also as conservative as it gets. One of my buddies had almost 10 minutes less of a deco stop last week on his computer compared to mine with the exact same profile.

Believe it or not, I do almost all my dives solo (which I'm sure will erupt some responses here). I do not act like Superman and am very conservative in my approach but really want to know if it's a better idea to have deeper deco stops. Sometimes, I barely hit the deco and my computer levels out once I hit 40ft as well.

I will definitely look into some more formal training. I am also a rebreather instructor and mixed gas certified, but I don't think there is a class for what I am looking for. Thanks for your answers and concerns - this is my first time on this site and I will definitely be back for more and look forward to anything else any of you have to say.

Aloha
Bryce

 

[JeffG]

I have no formal training on decompression diving

But you do it...Thats cool...expand your horizon...go beyond...where no man has gone before

I also have been diving this way for more than a year now and have had no adverse effects ever

If it doesn't kill me...it must be good

Believe it or not, I do almost all my dives solo

No doubt

I am also a rebreather instructor and mixed gas certified

Yea right....see your first statement

 

[Hyper-limits]

I will definitely look into some more formal training. I am also a rebreather instructor and mixed gas certified, but I don't think there is a class for what I am looking for. Thanks for your answers and concerns - this is my first time on this site and I will definitely be back for more and look forward to anything else any of you have to say.

Aloha
Bryce

You should take a formal course with all your experience that should be really easy.
You are mixed gas certified so you know the benefit of using EANx for deco why not use it. Why take the extra risks of using air for deco.

 

[oldmossback]

Hello. Recently I have been doing a lot of deco dives and I was wondering the health considerations both short term but primarily long term. I only do one dive a day, 5 to 6 days a week. Maximum dive depths 130-160ft(occassionally 180) on air with very random bottom times, giving me deco stops ranging from 7 minutes to 25 minutes. I have been diving for 11 years and an instructor for 5 and am just curious if this kind of diving is bad to do continuously, even at only 5 dives a week??? Should I also be doing some deeper deco stops than 15-25ft, maybe a stop at 60ft???

Thanks for your answers.

BryceGroak

Looks like your getting beat with an ugly stick here. Anyway, here's my two cents.

Your're comment of "random bottom times" concerns me.
What are you considering bottom time? From the time you reach the bottom to lift off or from the surface to the time you lift off the bottom? Makes a BIG difference in any of the old tables.

For example, (NOTE: you're not stating you're going this deep I hope,) however, the old bounce dive profile to 240 feet, called the Dr. Pepper thirty years ago, required a MAX. TOTAL of 10 minutes of bottom time, this included the "MOMENT" you left the surface till LIFTOFF from the bottom. Deco stops for 2 min's at 30 and 4 min's at 10 feet. 10-2-4, total time uw is 16 minutes on twin 71.2's.

You bust the total bottom time, say start counting from touch down to lift off from the sand as 10 minutes, and your stops are increased dramaticly and your air supply dangerously decreased. No safety bottles or safety divers staged on the way up and one has a good chance of drowning or getting badly bent.

THIS dive profile I just provided is considered by many to be an antiquated and dangerous. I suspect there were a few deaths with rec. divers using this profile........but I hope the meaning is clear. "If you're are out to go do what you're doing," and if you're hitting 160 or 180 feet, make sure of when you start the bottom time count. It should always be fixed on the surface prior to deep dives and followed to the letter. Never "Random"!

Remember, you gotta do all this figuring if you don't plan your dive prior to entering the water, assuming you're not Narc'd enough to know when to come up, let alone cognizant enough to figure new stops on your plastic dive tables I know you're carrying with you. You are aren't you? Safety divers? Extra bottles at 60, 30 and 10?

Better still, follow the advise of these guys/gals and get the necessary training. Getting bent is serious. Even a little bent can cause problems later. Hummm! I guess that's the answer to your question in the first place.

Good luck and good diving.

 

[mello-yellow]

First let me say that I have never had any classes on Deco beyond covering the Navy Tables in my Open Water Class in the 70's. And before attempting any decompression diving I plan on taking some additional classes. However, in reading the current Navy Air Decompression Tables, I read a 160' dive for 20 minutes bottom time requires the following,
4:40 ascent to 20'
3:00 stop at 20'
11:00 stop at 10 feet.

I realize the tables you are working from are a different source, but would this not be a valid profile for brycegroark, if he is only doing one dive a day?

Not looking to start a flame war, just want to learn.

Navy tables ASSUME there is a decompression chamber and crew standing ready.

 

[padiscubapro]

Wow. Thanks for all the responses. I have no formal training on decompression diving, actually - which seems to be the norm of all your responses. I have over 3000 dives, truly feel like I know what I am doing (in the least arrogant sense) but was nervous about the possible long term effects. I follow my computer - not any dive tables - for all my dives, which may be another problem in itself, according to some.

I also have been diving this way for more than a year now and have had no adverse effects ever (sometimes a bit exausted at the end of the day). I feel like some of the responses are a little extreme - especially since I always finish my deco stops and usually do multiple minutes more before ascending. My Suunto computer is also as conservative as it gets. One of my buddies had almost 10 minutes less of a deco stop last week on his computer compared to mine with the exact same profile.

Believe it or not, I do almost all my dives solo (which I'm sure will erupt some responses here). I do not act like Superman and am very conservative in my approach but really want to know if it's a better idea to have deeper deco stops. Sometimes, I barely hit the deco and my computer levels out once I hit 40ft as well.

I will definitely look into some more formal training. I am also a rebreather instructor and mixed gas certified, but I don't think there is a class for what I am looking for. Thanks for your answers and concerns - this is my first time on this site and I will definitely be back for more and look forward to anything else any of you have to say.

Aloha
Bryce

First your feeling exhausted at the end of the day could be from inadequate or improper decompression.. The suuntos are recreational computers they are not designed for decodiveing.. the deco is really there as an emergency measure.. The profiles are not shapped for the best results..

Just because you haven't hurt yourself yet is no proof you are doing it right.. What type of redundancy and gas reserves are you planning.. if you don;t know hwta your run times are going to be and how much gas you will beed eventually you WILL get hurt, its just a metter of time.. All gear eventually fails..

assuming you are using 25% as a bottom/deco gas for a 160ft dive with a short bt of 20mintes, it still requires ~30m of deco starting at least 60fsw, using 50% as a deco gas cuts the requirement to about 24 minutes

Before you become a statistic, learn to do deco dives properly either find a qualified instructor or at least a true mentor..

If you truely feel you know what you are doing, with the attitude presented above tells me you truely do not know what you are doing.. You can not treat mandatory stop dives the same way you treat a scuba-do dive....

some question for you to consider, since you are depending on your computer for deco, are you carrying a second one as well?? are you carrying a spare mask so in the event of a problem with your mask you can still read your computer to do the necessary stops?? are you diving with at least an h-valve with redundant 1st stages or doubles with redundant 1st stages?? if you answered no to any of these you should not be doing deco diving and are stastic waiting to be added.. These are just the tip of the iceberg..

 

[matt_unique]

If someone hoped in to say this was a troll I would believe it. To say "a few things do not add up here" is an understatement.

I would suggest the TDI Decompression Procedures course as a starting point. In my study I have learned how much deco theory has changed even in a just a short period of time. What your Suunto computer is telling you for deco obligations is not even close to what you would be taught in a current deco procedures class. I had a feeling you were using a recreational computer for deco. Before I learned basic deco theory I did some of what you described as well. Deco dives on air following my Suunto computer. I discussed one of my profiles with my tech instructor when I took the class. He showed me how far off I was compared to the the current software/models. It was shocking to say the least. Fortunately lesson learned without injury. I have used several software packages but prefer V-Planner personally.

Different tech instructors and tech divers in general will have their own limits for max depth on air. I know some who do not dive deeper than 100' unless on trimix. I know some that will dive to 180' on air. I decided 160' was my absolute max on air (or leaned Nitrox). I most feel the "martini effect" when I descend below 140'. When I am at 160' for example I feel a slight buzz. Not like I am out of my mind but just a litttttle something. This of course means I am much more affected than I necessarily "feel". This is my depth limit until I am breathing trimix.

It is also critically important to calculate your gas volume needs, many pieces of redundant gear you are probably not using now, slates to record your planned profile and stops and gas switches as well as bail out plans, what happens if you go over your planned bottom time, what happens if you loose your deco gas, etc., etc., etc. It's a whole new world compared to what is learned from recreational classes.

Take a class, get the gear, and use carefully planned profiles to avoid these Russion Roulette dives.

--Matt

 

[matt_unique]

... Russion.....
--Matt

Meant to type "Russian" there.....

 

[brycegroark]

Thanks for the beating guys!!! Point taken. More TDI Training to come for me for sure. I am so turned off by divers who think they know everything and definitely don't ever want to be thrown into that group.

Will keep you posted as to what I learn from this whole thing. I'm blown away so many people responded to this - these type of things are new to me and have really opened my eyes to chat boards.

Many mahalos and Aloha
Bryce

ps - thanks to Matt for offering a suggestion on classes - if anyone else is reading this, I would love to hear your recommendations on classes for my extended training!