Umbilical severed at 80 meters in North Sea

[Duke Dive Medicine]

This sounds like a gas jump in an open-bottom bell vs. a saturation dive. Sat divers' umbilicals come from inside the bell so it would be all but impossible to sever them from the surface. Glad there's a happy ending to the story... this must have been a solid dive crew.

 

[Akimbo]

This sounds like a gas jump in an open-bottom bell vs. a saturation dive...

Last I heard, that would be illegal in the North Sea. 50 meters max on air, mixed gas requires a bell system with mating deck chamber. As a result, virtually all diving below 50 meters is sat.

 

[Lemna]

This account by another diver on the Bibby Topaz clarifies a lot: Dive hose severed during DP vessel runoff

 

[Duke Dive Medicine]

Last I heard, that would be illegal in the North Sea. 50 meters max on air, mixed gas requires a bell system with mating deck chamber. As a result, virtually all diving below 50 meters is sat.

Thanks for the clarification. The blog post above makes it look like the diver's umbilical got fouled and parted vs. got cut. Makes sense now.

 

[Akimbo]

This account by another diver on the Bibby Topaz clarifies a lot: Dive hose severed during DP vessel runoff

28 minutes is a really long time below 250'! Any idea what bailout system was used? Hard to imagine being that cold and living -- hot water suits fit like coveralls for someone twice your size so you may as well be naked when the water stops.

 

[Crush]

Very excellent news. The commercial diving community takes safety very seriously, in part because they understand the dangers. A portion of the recreational diving community takes safety (in terms of redundancy, planning contingencies, etc.) less seriously, in part because they don't understand the dangers.

 

[Lemna]

28 minutes is a really long time below 250'! Any idea what bailout system was used? Hard to imagine being that cold and living — hot water suits fit like coveralls for someone twice your size so you may as well be naked when the water stops.

Probably twin 7L/300 bar tanks.

 

[Searcaigh]

Probably twin 7L/300 bar tanks.

When I worked offshore in the 80s it was a single 15L steel HP with 16% O2 in HeO2

Hot water suits were not exactly tight but we wore a fleece lined one piece suit called a wooly bear underneath to prevent burns from the hot water should the temperature get out of control.

 

[renoun]

More details from the professional mariners point of view posted to a diffearnt forum. It appears that the cause of this emergency was the failure of the dive ship's dynamic positioning system which is designed to hold the ship in position above the work site. When he DPS failed the ship drifted off and had to be manually returned to station and held in position before a rescue could be attempted.

 

[Akimbo]

Probably twin 7L/300 bar tanks.

We used AGA (now Interspiro) 3.8L/300 bar twins for bailouts in the 1970s and 80s... still my favorite Scuba rig in cold water. Who makes those HP 7 Liter bottles now?

In any case, they could not have lasted long after the hot water stopped flowing. His core temperature must have dropped like a rock. As a reference, Helium conducts heat about 6x faster than air and about 50% or our heat loss is through respiration.

You have to take slow deep breaths to conserve gas in a lightweight hat -- shallow breaths builds up CO2 in the oral-nasal mask pretty fast. I don't know about you guys but my respiration rate skyrockets when that cold water hits my crotch. He must have had amazing self-control or the cold shut his body down in ways science doesn't fully understand to last that long without gas.

Maybe some of you guys with more recent sat experience know: Are they running rich O2 bail-out mixes these days? Hyper-oxygenation might account for some of the added survival time. We used to keep ours the same as the umbilical mix, between .3 and .5 ATA.