In-Water Recompression

[Hassan Adly]

Hello,

I've done similar profiles with the RSE team before, and I'm ok too . In this case, the time spent by the divers *at* 90m was 10-11 minutes as far as I can see, preceded by a 5 minute descent. So yes, the deco is pretty aggressive and it wouldn't have hurt to add some more time. Not so aggressive though to account for how badly the bent diver was hit.

Using 35/25 provides benefits in gas management, and decreases DCS risk if you are careless higher up in the column. When you don't have 35/25, you have to watch your gas and do your 50% and 100% stops carefully. I don't think, however, that not having 35/25 means a bad deco.

The main thing is that when doing this kind of deco, you can't leave things to chance, which means that hydration, smoking, tight-fitting suits, and other things that badly affect deco, cannot be ignored.

Best Regards,

[mstroeck]

Quote: (Originally Posted by Hassan Adly)

Hello,

I've done similar profiles with the RSE team before, and I'm ok too . In this case, the time spent by the divers *at* 90m was 10-11 minutes as far as I can see, preceded by a 5 minute descent. So yes, the deco is pretty aggressive and it wouldn't have hurt to add some more time. Not so aggressive though to account for how badly the bent diver was hit.

Using 35/25 provides benefits in gas management, and decreases DCS risk if you are careless higher up in the column. When you don't have 35/25, you have to watch your gas and do your 50% and 100% stops carefully. I don't think, however, that not having 35/25 means a bad deco.

The main thing is that when doing this kind of deco, you can't leave things to chance, which means that hydration, smoking, tight-fitting suits, and other things that badly affect deco, cannot be ignored.

Best Regards,

Oops Hassan, you are right. It's 10 minutes, not 20, I'm oviously to stupid to read charts :-) It isn't even all that aggressive then. Still a few minutes short of what standard deco theory would tell you is "very probably safe", but I guess people dive these profiles all the time.

But I guess we'll have ample oportunity to discuss these things when I visit you in the middle of July :-)

[Red Sea Explorer]

Hi all.

I need to point out that doing such an aggressive Deco profile was a bad call on our part. We knew when we called the deco that it was not sufficient but decided to go with it for all the wrong reasons. I guess we got too arrogant after two weeks of 80-100 meter diving.

That said, the diver that got hit on the dive had other factors contributing to the hit as previously mentioned.

- Drinking the night before
- Very tight suit
- Did not drink or eat prior to dive.

Of course the main reason is the aggressive Deco. But the other divers were OK, and this goes to show how these factors really make a difference.

As for calculating Deco profile for a 90 meter dive I do a 3:1 ratio.

As for the deeper mix, I would add a 35/25 (36m bottle), only for gas management issues. I see that a deeper deco gas might speed up the Deco and make it cleaner, but if you have the gas to do the deep stops I believe the result is the same with out having to carry an extra bottle.

In the case that I do add this bottle then I do on it half the time that I have to do from 21-9.

[TDave]

Just to give a slightly more expanded look on what I did that day (more from a general interest point of view than anything else), my profiles were something like this.

Dive 1
Nitrox32
32m Max Depth
24m Average
40 Minute Run Time

45 Minutes Surface Interval

Dive 2
As per Red Sea Explorer's print out

45 Minutes Surface Interval

Dive 3
Air
30m Max Depth
21m Average
40 Minute Run Time


As we've already mentioned, yes the deco on the second dive was aggressive, and also as was pointed out, we certainly knew this when we planned it on the way up. However, for me, I was happy to roll with it as I wanted to see how my body would handle it (sounds stupid, I know, but I mean that given we [myself and Faisal] had moved set points around for ourselves before in slightly shallower depths I was happy to try it here).
This was the wrong choice given that one member of the time had not been with us over the previous year when we'd been trying these things. But, equally, the third diver should have said if they also weren't happy with the deco - this is why we plan it and then show the options around underwater. This, too, was a mistake.
It's also true we could have added a 36m bottle (JS1scuba, I don't know if this is what you meant in your post or whether you were suggesting a 36% bottle as a replacement for the 50%. Personally I wouldn't be without the 50%) which would have saved us a little on our minimum gas calculations and made the 36 - 21 segment more efficient. Given the dives we've done before to various ranges with and without the 36m bottle I don't know if it was a critical addition for this dive, but I'm happy to be corrected.

However, as things turned out, even with the profiles surrounding it and with the deco being particularly aggressive, it appears to me that despite the above mentioned mistakes / poor judgement calls were overshadowed by the other predisposing factors in the third diver (inadequate hydration, constrictive semi-dry, etc.), which again is something we, as the team, should have been more aware of and sensible with.

As for how I felt after the dives? Honestly the same as nearly all the other dives I've done. No particularly excessive fatigue (besides my general tiredness brought on by filling the Helium till 2:30am and then waking the guests up at 5:30 :-)). I obviously didn't get chance to go for a run or really test myself (running around a boat plowing through decent-sized waves didn't appeal to me...) but even so it felt right enough. Whilst I didn't dive again for the rest of that day (except as support during the IWR), the 2 weeks following that have been 4 dives a day, every day, in the recreational range (<30m) without any ill/cumulative-effects (of course, I'm still Tired...)

Just my two cents

[Martin Burnard]

"Whilst I didn't dive again for the rest of that day (except as support during the IWR), the 2 weeks following that have been 4 dives a day, every day, in the recreational range (<30m) without any ill/cumulative-effects (of course, I'm still Tired...)"

That's alot of diving by any standards, so I guess your diet, hydration, and fitness, combined with lower stress levels (from competance and familiarity), would give you a head start over your third member.

This really highlights that when diving with somebody new to us (any of us) we need to be aware of those with MORE experience then ourselves, as well as those with LESS. Both can unintentionally cause a problem.

Thanks for the post.

Martin

[mstroeck]

Quote: (Originally Posted by TDave)

But, equally, the third diver should have said if they also weren't happy with the deco - this is why we plan it and then show the options around underwater. This, too, was a mistake.

It is hard to believe how far out of their depth adult persons are willing to go when they are with more experienced people. On a (dry) caving expedition, I had a funny situation a few years ago. A guy who nobody really knew but labeled himself as an "experienced cave explorer" came along on a relatively short survey trip on the first day of the expedition. After descending several easy shafts, we came to a short wall that had to be ascended by rope -- at which point our "experienced" new friend revealed that he had never actually done that before! By that time we were at -350 meters, so he had plenty of time to learn as he went along towards the exit …

[Ahmed Adly, Marlin Inn DC]

Quote: (Originally Posted by Red Sea Explorer)

- Carelessness on behalf of the team having opted for an aggressive deco profile. We decided to ignore the fact that we were 3 meters deeper than the planned Average depth.
- Slow and untimely assent due to the fantastic things we saw on this virgin wreck in the 85 and 80 meter range. (It can be seen on the profile.)
- Predisposition of the hit diver due to dehydration having had several drinks the night before and not had any water or food prior to the dive.
- A Semi dry suit that was so tight it took two people to get the diver into. It was so tight that t-shirts stayed dry under it. It was constricting the circulation of the blood thus hindering Decompression.

Was this "thrid member" a smoker?

[Mark Chase]

Just looking at the profile and working on an average depth of 86m for 22mins including a 20m/min decent, I ran the numbers through deco planner.

Using my normal 20/80GF profile it came up with 127mins of deco

Running a massively aggressive 35/100 GF it came up with 90mins of deco

Running straight Bhulman of 100/100 it came up with 66mins of deco

Ruining VPMB with level 2 safety it gave 118mins of deco

Running VPMB with 0 safety it gave 104mins deco


Add to this the incredibly slow ascent? averaging less than 2m/min between 80 and 20m and that is one hell of a lot of on gassing still going on on the way up. This on gassing phase has not been added to the shallow deco.

Running 45mins of deco on this dive it beyond aggressive. The bloke who did it with you was mad and with his level of pre dive prep he was pretty much guaranteed a hit.

Christ knows how you get away with running profiles like this but to take a stranger along for the ride has my eyebrows nailed to the top of my head.

I post this in the hope of preventing anybody from copy cating the profile. Running deco like this takes a vast amount of personal knowledge of your body's reaction to the stresses involved.

Screwing up a short exposure deep bounce dive like this usually results in type 2 spinal an neurological bends. These are far more serious than Type 1 bends associated to longer exposures deep dives. Brain damage and paralysis are possible outcomes.

The description of the bend in this case identifies the bend as a type 2 Neural bend.

Early treatment via in water decompression probably saved the bloke from being in a wheel chair. Not that he gave a s#it because he cared so little for his own life that he was apparently diving again the next day.

If I had a boat and he was on it I wouldn't let him dive.


Thank you for posting the IWR stuff, it was interesting and I am supportive of its use. I don't want a ruck but I felt the voice of reason was needed to balance the thread.

Too many newby DIR divers carving too much off their deco too quickly worries me.

If you want out of the water fast on this dive simply add a AL40 of 21/35 at 66m and you could more safely cut the deco to 65mins runnig a 30/90GF profile

ATB

Mark Chase

[Red Sea Explorer]

Hi Mark,

I agree with you, every diver needs to know what their body can take before they jump in and do what someone else is doing.

I also stated that mainly the primary mistake was the decision to do such little deco for the dive. The third member of the team was also part of the decision making process and knew the risks involved.

I guess he learned a good lesson and so did we.

I opted to share this experience, at the risk of being chewed, in the hope that people learn from our mistakes.

Best

[Mark Chase]

Quote: (Originally Posted by Red Sea Explorer)

Hi Mark,

I agree with you, every diver needs to know what their body can take before they jump in and do what someone else is doing.

I also stated that mainly the primary mistake was the decision to do such little deco for the dive. The third member of the team was also part of the decision making process and knew the risks involved.

I guess he learned a good lesson and so did we.

I opted to share this experience, at the risk of being chewed, in the hope that people learn from our mistakes.

Best

I do appreciate both your honesty and frankness. I am in no position to preach because I have done 66m gas switches with 30bar left in back gas, 70m air dives and other equally mad things that make me totally unqualified to cast the first stone.

I hope you will forgive me in that I felt that some comparative information was required to demonstrate the enormity of what you lads are up to.

As stated before in this thread divers can sometimes get swept along into doing things they shouldn't be doing. Maby i am just an old fart who worries too much but I often post printouts of my profiles and I get PM's asking why I did Sooooo much deco. When I work out the dive using DOTF I don't find that I have done THAT much extra but when their interpretation of the dive comes back I find them rounding EVERYTHING down and achieving significantly less deco than me.

I am 42 fat and a light smoker but I play 10 hours of competitive badminton a week and can still do a mile in 5min 10. I don't drink and dive I don't smoke before a big dive, I take hydration seriously starting 48 hours before a big dive and I think about my food intake and recent physical condition when planning deco.

I once had to bailout on to a 100/100GF plan or die. Those were my options. I made it and I didn't get bent (amazingly) but I went straight back to my granddad 20/80GFs for the next dive.

I like diving and I don't mind being in the water for up to 180mins max. I have done some hairy dives over the years but I never once saw the point of ripping the piss out of deco.

Take care M8

ATB

Mark Chase