"Accidental" deco with 1-day group, what to learn?

[Caveeagle]

I made several mistakes here -- one being that I didn't then tell him "no, we're terminating the dive", but it's intimidating to do that to an instructor and a group of people who are all more qualified than you. That's what I'm trying to work past -- and what I'm asking for advice on.

Kalleth, don't beat yourself up over this. At the point you started to run short on NDL time, I don't see how you could have done much different other than calling the dive, and I certainly understand how you would feel pressure not to do what would have probably ended the entire team's dive. (right?).

The learning, or take-away as I see it:
1) Don't dive with a group (>3), especially when you are the least experienced diver and will feel peer pressure to 'go along' well past your comfort.

2) If you are forced into this... Make sure you clarify what your profile limits are, or what your "turn criteria" is. So that nobody will be surprised, or disappointed when you 'thumb' the dive.

3) Get nitrox certified asap. I saw your post about avoiding 'task loading', but it sounds like you are already doing the dives. For the average diver, using Nitrox should not add much stress to the dive, and would have kept you out of deco on this dive. For a ~100' dive, EAN 30-32% should get you around 23m..

 

[Diving Dubai]

I wouldn't call 1 hour (I assume OP's "1h" stands for) SI "short".

My wife and I both dive Eon's, and while the algorithm, is different and less conservative, we've noticed that on back to back deep dives, if you only have a 1 hour SI then it gets grumpy, especially so if you're on the mid point conservatism. It generally likes 90 mins.

@kalleth

I'm not going to beat you up, you did the best you could given your level of experience. Malta is a place popular with BSAC divers, and Decompression is taught as part of their AoW (equivilent) - while not excusing the guide they might be used to people who have deco experience.

My only point, is that while you had gas, you may not have had enough. In that situation I would have shot a DSMB, and signaled to the guide I was going up to minimise my deco. If you are diving to that depth, then I would suggest looking at the Apex finger spool which carries 50m of line. It's quite compact and light and easy to grasp (I use one) I suggest the 50m because if there is a bit of a current and the DSMB gest pulled along the surface, you don't want to run out of line. You should of course practice DSMB deployments before you need it for real.

 

[fmerkel]

Gargage in, Garbage out. Until you justify the reasoning behind the 5%point adjustment in N2, I respectfully suggest you are proving the "Garbage in" side of that old adage.

Possibly true. Noted.

Yes, do you know exactly what variables the Uwatec tweaks to modify the profile? I bet its NOT N2.

No idea. Typical of a lot of 'recreational' computers you have no way of knowing or finding out.

Sell it to someone who wants a more conservative unit..... and get another Uwatec if that's what you like. I got my last Aladin Pro for $10 and swapped in a $8 battery. Works just find now.

Ha, that's how I got the Favor.
Believe me, we've thought about it, still thinking about it......

For now this is something we are trying. We compare profiles closely after each dive. This is a new tweak, working well for single dive scenarios but has not been explored on mx dive/mx day outings with Nitrox. It could go completely outside reasonable parameters in that situation. We WILL be monitoring.

For now - DO NOT DO THIS TWEAK.....NOT RECOMMENDED. Danger! Danger! We are probably nuts.

The salient point is that Suunto is a conservative computer, and that different computers can vary significantly on exactly the same dive profile. If computer manufacturers were putting out computers that got people bent all the time there would be lawyer hell to pay. I ask again, which one is right?

 

[dmaziuk]

I made several mistakes here -- one being that I didn't then tell him "no, we're terminating the dive", but it's intimidating to do that to an instructor and a group of people who are all more qualified than you. That's what I'm trying to work past -- and what I'm asking for advice on.

I think he was wrong: e.g. when we did the 110' wreck on Roatan the DM quite clearly said that a) the bottom was where "your computers may not like it" and b) we're not going to stay down there long and we're coming up and doing the rest of the dive much shallower. With that information given at the briefing everyone could decide for themselves whether to possibly go "accidentally too deep", or stay up higher, or whatever, before we splashed. I think if he just told you "your computers may go into deco for a bit but we'll have plenty of shallow time to clear it -- provided you watch your air", we would not be having this conversation. I don't believe getting over your computer's NDL is a "YOUR GONNA DIE!!!" offence, but getting there unexpectedly and out of your comfort zone is not a good thing.

 

[toby43]

Hey there! First post, mainly because I'm looking for some advice on what happened today

I'm a PADI AOW with deep cert on holiday in Malta with about 75 logged dives before today. I'm here visiting family, but I decided while they were working I'd go diving to while away the hours, with a local dive shop. I've done this before a few times in Mallorca, Florida and now here in Malta, twice -- though this shop was new to me, and today was the first time I've used them.

They're a PADI 5* / tecrec and instructor training shop.

I generally dive on holiday in warm water, not in the UK recently, and I'd consider myself a competent, conservative vacation/occasional diver, usually -- but I am not a "tec diver" or an "advanced diver". I'm calm in the water, rarely get flustered, and I'm rarely the person in any group with the highest gas usage.

As luggage space is a factor, I take my own computer (suunto vyper, ~8y old regularly serviced) and a prescription dive mask, and rent the rest from whatever dive shop I'm joining for the day.

To the dives themselves; today we visited a wreck that sits in between ~25 and 35m. We dove it the first time around well within our ND limits -- entered the water on 220 bar, left with 70, on a 15L tank. Impressive vis, really enjoyed the dive.

Then we took a 1h surface interval and the instructor (acting as a guide -- there were 3 other clients, me, and the instructor, total of 5 -- nobody was taking a course) briefed the second dive, which was to include light penetration where an exit route was always visible. I was a little worried about ND limits as he said we'd first look under the keel at ~35m. I didn't mention anything about them at this point because we were all diving computers.

The dive began as the first dive of the day did, a reasonable swim at ~8m out to the wreck, then dive down to the keel, have a look around, and rise up to ~28m for the penetration. At this point I have 6 minutes remaining on my computer of ND time and pointed this out to the guide, who understood and 'okayed' me. I am fine with the dive at this point, everything is going great. Air remaining ~170 bar.

We penetrated through to an area where I remained in view of the "chimney" style exit, the other three members of the group and the guide descended a level (about 3 or 4m away from me, the guide was always in view) to swim around the large room for a moment. At this point I check my computer and have one minute of ND time remaining, which I signal to the guide. He makes the "okay" sign, and tells me to stay where I am.

I am getting somewhat nervous at this point, but I remain calm and wait.

One minute later, my computer beeps, and I signal using my little finger (the sign we had agreed in the prebrief -- i've not been trained on it, as far as I can remember, but some googling says this is a 'deco' sign). The guide again "okays" me, and tells me to wait.

I watch the "ascent time" creep up on my computer to 6 minutes, then 9 minutes, eventually reaching 20 minutes with a 3m ceiling. During this time I am signalling with my little finger, tapping my computer, but I'm not sure how to signal beyond that as I've not had training on decompression diving (nor, really, do I want to yet). The guide then swims up after gathering the rest of the group, the guide reaches me, and we exit the wreck with about 130 bar in my tank.

We subsequently swim back to our entry/exit point, and then spend ~25 minutes decompressing at 5m (after a 10min swim at 8m) before surfacing. I left the water with 60 bar remaining, after a total dive time of 74 minutes. I'm pretty cold in a 3mm suit at this point, and I need a pee. My computer was clear before I ascended, and I have no adverse symptoms of DCI/DCS now, 4 hours after leaving the water. I think I'm fine (I decoed as instructed, I'm sure I am....)

I guess I have some questions for some more experienced divers;

1. I know I should have been more assertive in ending the dive as soon as I felt uncomfortable once I reached zero time left on my computer. Would a "thumbs up" signal have been appropriate then?
   
2. After leaving the water, the german clients didn't seem fazed by the deco, saying "this is normal for a wreck on air at this depth". Should I have been expecting it, even though it wasn't briefed as a deco dive, and everyone was aware of my cert level, given this was a repetitive dive on air to a deeper wreck?
   
3. Is this normal (leading question, I know) at the more technical dive centres? There's a certain amount of trust (as an occasional diver) I place in the dive masters leading a dive when I dive alone with a "pick-up" group. I perhaps naively assumed that PADI -- at this 5 star certified centre -- would prevent this from happening, and I'd be diving within my comfort zone, to the level I'm qualified doing.

I'm generally a very conservative diver and this is the first time I've put my computer into deco mode, and I'm in no rush to do it again -- especially not with a single tank, no stage bottle, buddies who i've never dived with before and rental gear I'm not familiar with. Really, any advice is welcome -- including "you donut, why didn't you end the dive!".

What did your buddy do? What did their computer say?

 

[scubadada]

You have to dive your own computer, no deco or deco. You have the choice of many decompression algorithms, make a choice you can live with. Many divers do not know that there are significant differences between the available algorithms. It is a mistake to go with brand without understanding these differences.

 

[archer1960]

Hey there! First post, mainly because I'm looking for some advice on what happened today

...

We subsequently swim back to our entry/exit point, and then spend ~25 minutes decompressing at 5m (after a 10min swim at 8m) before surfacing. I left the water with 60 bar remaining, after a total dive time of 74 minutes. I'm pretty cold in a 3mm suit at this point, and I need a pee. My computer was clear before I ascended, and I have no adverse symptoms of DCI/DCS now, 4 hours after leaving the water. I think I'm fine (I decoed as instructed, I'm sure I am....)

...

I understand your concern that you didn't plan a deco dive, but you actually did do your proper deco, and your computer told you so, so you shouldn't expect any DCS (though of course it's always possible, even without exceeding NDLs). When I was in Coz earlier this month, my buddy and I knew that on one of our dives, we would be pushing the no deco limits. So we discussed it and realized that with the profiles the DM was briefing, we would essentially be doing deco on the later part of the dive, and would just do an extra-long safety stop if we did run out of NDL earlier. It turned out that we never exceeded NDLs, though we did come within a few minutes on one dive. On the way up after doing the Devil's Throat (bottoming out at 134 fsw), we (as pre-briefed) did 3 min at 40' and then 8' min at 15' just to be sure, even though we only got to about 5 min of no stop time.

 

[Centrals]

I really do not understand why most dive guides are quite happy with only an hr surface interval. Always enjoy to look at their faces when I said minimum is hr and half for me. But I do make my point before the 1st dive.
However, diving with a group of strangers from different countries is never easy. We all have funny ideas!

 

[DevonDiver]

It's no surprise to hear of a "highly certified" diving center acting irresponsibly to their diving customers. Agencies don't regulate non-training activities whatsoever.... there's no standards to be held accountable to.

Your 'pro' guide shouldn't have taken you inside a wreck. He/she shouldn't have taken you into deco. He/she shouldn't have ignored your communication regarding no-deco/deco status.

It's absolutely, unforgivable, unprofessional and unethical dive supervision.

It's worth reading some articles about complacency and diving...also research the term 'normalization of deviance'.... then remembering that recreational "professionals" are often the most complacent divers around. Some of the worst divers I've ever encountered were 'pros'.

For that reason alone, you MUST NOT abdicate responsibility for your safety to any other diver, even a pro.

If you know something is wrong.... or you are not comfortable.... then abort the dive, return to the surface and ensure your own safety. If you give the 'thumbs up' abort signal... that's the end of it. No ifs... no buts... no maybes. ANY diver that doesn't respect that isn't safe to dive with.... 'pro' or otherwise.

I know I should have been more assertive in ending the dive as soon as I felt uncomfortable once I reached zero time left on my computer. Would a "thumbs up" signal have been appropriate then?
​

Yes. Thumbs Up signals 'end the dive'..... it's not a request or a question.... it's a command.

If I gave that signal and it was ignored or over-ruled, then I'd take the necessary steps to preserve myself, regardless of the 'pro' or the group. It's their failing, not yours.

YOUR responsibility is to track your gauges and give ample, advance warning to the guide/group/buddy. There may be specific safety reasons why an immediate ascent, or splitting a group, is not prudent.... and your dive guide may be considering that.

Entering a wreck... or 'doing a set route'.... or 'not wanting to cut the dive short for other divers' are NOT specific safety reasons.... they are 'customer satisfaction' reasons. As such, they are irrelevant in any decision making on ending the dive.

After leaving the water, the german clients didn't seem fazed by the deco, saying "this is normal for a wreck on air at this depth". Should I have been expecting it, even though it wasn't briefed as a deco dive, and everyone was aware of my cert level, given this was a repetitive dive on air to a deeper wreck?​

I hate to sound like your parents (probably).... but if someone told you to jump off a bridge, would you do it?

Some divers are enormously complacent.... dangerously slow. Advocating dives beyond your comfort zone and training threshold is a strong indicator of massive complacency and a dangerous level of normalization of deviance.

Read these 3 articles, they are all very applicable:

Normalization of Deviance

Diving - The Experience Paradox

The Biggest Risk in Diving (and how to avoid it)

Is this normal (leading question, I know) at the more technical dive centres? There's a certain amount of trust (as an occasional diver) I place in the dive masters leading a dive when I dive alone with a "pick-up" group. I perhaps naively assumed that PADI -- at this 5 star certified centre -- would prevent this from happening, and I'd be diving within my comfort zone, to the level I'm qualified doing.
​

This behavior is a polar-opposite to technical diving mindset. It is merely BAD recreational diving..... it's unprofessional and irresponsible.

You need to understand... "5* Dive Center" means nothing at all. Dive centers are not agency audited on the safety or compliance of their fun diving activities. There are no standards applicable....and no repercussions for bad practices.

What agencies RELY UPON is divers contacting them about these sorts of issues. Instead of posting on Scubaboard... did you try asking PADI directly about the validity and safety of how their 'qualified professional' ran your dive/s? You should....

Consumer Protection

Nothing is ever gonna change until divers start informing agencies about these incidents. Trust me... that was an "incident" by any definition.

Also..... did you raise your concerns with the dive center directly? You should have.... it may be possible that the dive center management don't know what their window-licking instructor is doing whilst out on the boat with customers.

Honestly.... sometimes I think the scuba industry apply the following perspective to risk management in fun diving activities:

There's some seriously over-inflated egos amongst the hordes of 'dive pros'.Dime-a-dozen 'professional' qualifications swiftly leads the weaker minded to a rapid over-estimation of their capabilities and competency. They've just not had enough experience to learn lessons from when things go wrong..... so they push their customers beyond safe limits based on ignorance and false assumptions.

Novice divers tend to 'trust' dive pros..... well.... with 25 years experience (12 as an instructor).... I wouldn't trust many of them.

I recognize experience..... real experience.... by how it shapes a conservative, risk adverse mindset in divers. When that mindset is lacking.... you've got an over-inflated cowboy on your hands.

 

[DevonDiver]

...(unfortunately), these 'guides' do it because of frank ignorance a misplaced confidence, such as: This does happen - they know the site, they have probably done the dive dozens (or more) times before, etc. And, from my perspective, that doesn't make it right - for the customer. You were, frankly, put in a rather compromising position.

It's indefensible behavior.

The diver HAS A RIGHT to define the limits of the dive they feel prudent to conduct.

Those limits may be caused by a conservative computer...but the 'rules' (recommendations) for computer diving are very clear that the dive parameters are limited by the most conservative computer.

A diving customer may also elect to increase the conservatism settings on their computer. That may be because they are concerned about DCS pre-disposing factors that might apply to them in general, or on a dive-by-dive basis. That, again, IS THEIR RIGHT.

Lastly, the diver may decide to informally add a measure of conservatism by ascending from the dive at a point before their NDL is reached. That also IS THEIR RIGHT.

No 'diving pro' has the right to decide otherwise.... to coerce or otherwise pressure or influence the individual diver to go beyond whatever that diver has prudently decided as their limit.

Do not underestimate the 'peer pressure' that can be exerted on novice divers by supposed 'professionals'. It's important to understand that novice divers assume that professional divers know better. That assumption may be very wrong... but it's entirely understandable.

Beyond that, it's unprofessional and irresponsible to assume you (the dive pro) know better than the individual diver. No dive guide has sufficient intimate knowledge of their customers' well-being, health, diving history, DCS pre-disposition and/or state-of-mind to make any decision to over-rule any choices the diver has made to curtail the parameters of their dive/s.

What the customer-diver can do.... should do... is communicate their parameters before the dive begins. That is all. State your limits in advance and if they aren't respected, make a decision to preserve your own safety.

This should happen, ideally, around the time of the dive briefing. That dive briefing...given by the 'pro' should include the dive depth and time parameters....and also the limitations to be applied in regards to NDLs.

For instance "Do inform me immediately if/when you get within X minutes of your computer NDL".

This...."professional approach" ... as DMs are trained to do.... prevents incidents happening like the OP describe..