100m dive

[PfcAJ]

If you’re going to be a technical diver, you really gotta be able to recognize and take some playful ribbing. Geesh.

No one uses “stroke” seriously anymore. And Kensuf is a super nice guy, polar opposite of me. I’m certain it wasn’t his intention to make you feel put down.

Uhh... you sure? Asking for a friend.

 

[Superlyte27]

Actually, when I wrote that YOU did come to mind. Lol

 

[Superlyte27]

And I'm literally still laughing. That was a funny post.

 

[kensuf]

Here's why I say stroke crap.

What's the most common cause of death in technical diving? Improper gas switches. This dive plan already has 4 different gases for what is effectively a short bounce dive. Every time you add an extra gas switch you are increasing the complexity and the chances of screwing up, so try to maximize the utility of the gases and minimize the gas switches (I like doing a gas switch no more frequently than once every 5 stop depths).

We might then ask "why does he want to use 80%"? You wrote:

What's everyone's thoughts on EAN80 vs. 100% O2? In light of the plan outlined above, EAN80 would obviously lower OTU's and CNS% and reduce the need for air-breaks whilst only increasing the total runtime by 3 minutes (i.e. a runtime of 106 minutes as opposed to 103 minutes).

Now adding 80% doesn't really buy you much in terms of benefit for this dive plan. In terms of lowering your OTU's and CNS%, your CNS clock is only going to be on the order of 60-70% from the original dive plan if you use 100% oxygen to begin with and at 9m 80% has a PO2 of 1.6 (just like 100% is at 20'). All this while you're reducing the usefulness of your 50% gas and introducing an earlier gas switch.

Additionally, the first proper first aid for DCS is 100% oxygen -- you should ALWAYS have oxygen available for you on days you do 100m dives. Heck, I usually keep an extra bottle of oxygen "for the drive home" in case stuff goes wrong.

Finally, AJ hinted at this but I had missed it until this morning because of the metric to imperial conversions. Your plan to add 80% is because you're here worrying to hell about CNS and OTU's but you're completely missing the boat on having enough bottom mix to do the dive safely. 2x12L cylinders are pretty small, for those of us on this side of the pond that's basically LP77's.

A CNS clock of 70% is not going to mean you will die from oxygen toxicity. 130 OTU's on a dive is not going to mean you will get pulmonary oxygen toxicity. Running out of gas does mean you will likely drown.

You're worrying about the wrong things, and that's why I said "stroke crap."

 

[KenGordon]

Here's why I say stroke crap.

What's the most common cause of death in technical diving? Improper gas switches. This dive plan already has 4 different gases for what is effectively a short bounce dive. Every time you add an extra gas switch you are increasing the complexity and the chances of screwing up, so try to maximize the utility of the gases and minimize the gas switches (I like doing a gas switch no more frequently than once every 5 stop depths).

We might then ask "why does he want to use 80%"? You wrote:



Now adding 80% doesn't really buy you much in terms of benefit for this dive plan. In terms of lowering your OTU's and CNS%, your CNS clock is only going to be on the order of 60-70% from the original dive plan if you use 100% oxygen to begin with and at 9m 80% has a PO2 of 1.6 (just like 100% is at 20'). All this while you're reducing the usefulness of your 50% gas and introducing an earlier gas switch.

Additionally, the first proper first aid for DCS is 100% oxygen -- you should ALWAYS have oxygen available for you on days you do 100m dives. Heck, I usually keep an extra bottle of oxygen "for the drive home" in case stuff goes wrong.

Finally, AJ hinted at this but I had missed it until this morning because of the metric to imperial conversions. Your plan to add 80% is because you're here worrying to hell about CNS and OTU's but you're completely missing the boat on having enough bottom mix to do the dive safely. 2x12L cylinders are pretty small, for those of us on this side of the pond that's basically LP77's.

A CNS clock of 70% is not going to mean you will die from oxygen toxicity. 130 OTU's on a dive is not going to mean you will get pulmonary oxygen toxicity. Running out of gas does mean you will likely drown.

You're worrying about the wrong things, and that's why I said "stroke crap."

A 12 here is 232 bar which I think counts as HP in the colonies. Anyway 100 cu ft.

Too many gas switches? If only someone could come up with a machine that could change the gas for you, maybe even optimising it for depth. It would revolutionise deep diving.

 

[Superlyte27]

I'm not arguing Ken, but where's the data on gas switches being the biggest cause of death on technical dives. The last 10 tech deaths in the USA had nothing to do with a gas switch, unless you count Carlos, which was refusal to analyze.

 

[kensuf]

Too many gas switches? If only someone could come up with a machine that could change the gas for you, maybe even optimising it for depth. It would revolutionise deep diving.

I love those machines. I spent 5 hours on one today and came out of the water with a CNS clock much higher than 70% and appear to be fine.

I'm not arguing Ken, but where's the data on gas switches being the biggest cause of death on technical dives. The last 10 tech deaths in the USA had nothing to do with a gas switch, unless you count Carlos, which was refusal to analyze.

I don't have the data to back my assertion up, but historically there were quite a few fatalities caused by bad gas switches, usually from improperly marked / analyzed bottles or failure to follow procedures. I am sure given how many there were definitely keeps that cause at the top of the list.

BTW, you're forgetting Jim Miller.

 

[Superlyte27]

Nope, I wasn't. That was 7 years ago if I recall correctly. Sadly, there's been 10 deaths since his.

 

[ajduplessis]

?

In short it refers to unsafe divers and practices, see below

"The term *stroke* was coined by Parker Turner, the original project director of the WKPP. Parker, much like Irvine, had a no-nonsense approach to diving and running the WKPP. Parker had his rules as to the team and one either followed them or they weren't on the team. It was as plain and simple as that. But what Parker found over the years that there were so many people trying to get on the team without the willingness to put in the requisite work. Instead they would come up to Parker and tell him how they had done this dive or that dive, blah, blah, blah and Parker said that he was sick of these guys *stroking* him to get on the team.. That's the evolution of the word.It has since been expanded to include diver's that approach diving with an unsafe and/or cavalier attitude towards diving.."

The responding party did not answer your question, just plain negative personal attack IMO. Calling someone or their comments a stoke is in direct infringement of this board rues. IMO the poster attacked you describing you as an unsafe diver without any reasoning or explanations.

 

[leadduck]

Interesting thread. There was one about EAN80 before: Request for opinions about standardizing on EAN80

pPO2 1.6 is OK during deco and divers exceed their CNS clock regularly without issues during deco. There are however factors such as exertion (pCO2), certain drugs (pseudoephedrine, cortison), and maybe cold, that greatly reduce your tolerance to oxygen, and with such factors present divers had twitches, nausea, irritability already below 50% on their CNS clock. The CNS clock becomes very unreliable and there's great personal variability, so the safe way is to deco on 1.3bar pPO2. So I think if a diver has to do a long 6m/20fsw stop (not shallower due to waves in the ocean) on a stressful dive with current in cold water, he may not want to do that 6m stop on 1.6bar pPO2 and use EAN80 instead at 6m.