Divers disabled on 270-meter dives, firm convicted - Australia

[Akimbo]

This is my guess. It's my understanding that HPNS can be exacerbated by a rapid descent. Theoretically, dive plans to this depth should account for that and calculate it into the descent rate. Perhaps, they are saying the divers were 'blown down' at an unsafe rate?

I have not heard of HPNS having long term neurological symptoms. Not many sat chambers are even capable of pressurizing anywhere near descent rates that are common in Scuba diving.

For other readers, compression rates for saturation divers is normally pretty slow. We used 1'or 300mm/minute but there are a lot different tables. Here is the US Navy's current table:

Other readers may find this thread helpful:

Info - What is Saturation Diving?

A lot of divers are not sure what Saturation diving is so I thought a quick summary might be useful. Saturation diving was developed by the US Navy's Captain George F. Bond (affectionately known as Papa Topside) in the 1960s. All divers know that the deeper we go and longer we stay, the longer...

scubaboard.com

My brother was on an emergency blowdown in the late 1970s to 600'/183M for an entangled manned submersible rescue. He didn't mention HPNS but everyone was in pain from compression arthralgia.

 

[SlugLife]

How well known is the science behind these kinds of injuries and long-term diving at those depths?

The court-case itself might be interesting to dig into, although that's a somewhat "dangerous" thing to say (as they tend to be long and boring). I'd be curious as to how the dive was initiated, the timeline of warnings, etc. And whether anyone discussed if a dive at those depths would be safe or not.

 

[L13]

How well known is the science behind these kinds of injuries and long-term diving at those depths?

I'm pretty sure saturation diving is far better understood than scuba, particularly than deep scuba. But still a lot unknown. That should caution us when it comes to scuba.

 

[sea_ledford]

Isn't this the incident that blew them down to depth at an insane rate?

Found a bit more:

Deep-sea divers in high pressure mishap

SEVERAL elite commercial divers were seriously injured in an incident off WA’s northern coast.

www.perthnow.com.au

The claim is that the men were pressurised at rates so fast, industry experts compared them to the emergency pressurisation rates only permitted by the US Navy in extreme scenarios such as a submarine rescue or recovery of a nuclear warhead

 

[Miyaru]

Back then, there were complaints about the rapid blowdowns:

Mr Bray said blowdown schedules for deep saturation dives of 230-240m elsewhere in world ranged from 17 to 26 hours. He claimed there was “no table in the world on a standard dive that says it’s OK to do it in eight or five hours”.

Apart from the rapid blow down schedule — four times faster than what other diving companies recommend for such depths — questions are also being asked about why the operation continued and divers were allowed to leave the bell after they complained of acute symptoms of high-pressure neurological syndrome (HPNS) following blow down.

Edit:
see also this thread

 

[Searcaigh]

For other readers, compression rates for saturation divers is normally pretty slow. We used 1'or 300mm/minute but there are a lot different tables.

That sounds about right.

We used to blow the system down to 10m fairly quickly to make sure everything sealed ok, then after inspections completed a reasonably slow descent to working depth.

We followed COMEX tables back then which were probably based on US Navy Sat tables and modified slightly, why reinvent the wheel eh!

 

[John C. Ratliff]

I have no experience with saturation diving. But I do have a lot of experience with accident investigation. If you have 7 out of 15 divers experiencing long-term symptoms, that’s 47% of the divers. Having those symptoms continuing to happen while the divers were saturated, and continuing to work, would constitute some fairly large liability for those in charge of the dive.

SeaRat