Well, what could go wrong?

[Crush]

Statement:

1. 65% of injuries are to male divers, so statistically it is likely Bob who was injured;

Response:

Not necessarily ... did DAN mention what percentage of all divers are male?

If more than 65% of all divers are male, then Bob is less of a potential statistic (per capita) than Karen.

... Bob (Grateful Diver)

You are, of course, correct in your analysis of what the stats mean. I find that the more details I go into, the more someone tries to pick them apart. Well, here goes:
1. You are correct - the dive accident rate of 65% for males was not normalized to the diving population;
2. DAN's Project Dive Extravaganza (PDE), reported on in the same DAN publication, tracked 1180 divers, 31% of which were female. Now, PDE divers may not be a representative sample of all divers but the mean age of injured divers, 43±12 years, remarkably similar to the 42±12 years age of all PDE divers;
3. Assuming that PDE divers are a good representation of the diving community, males are slightly under-represented in the rate of diving accidents. Summary: it is likely that it was Karen who was injured if they were diving as a pair, but in general Bobs (males) get more injuries than to Karens (females) since more men dive; and
4. As an aside, men and women have similar dive profiles. Subtle differences are that women tend to have more 0-29 fsw and 30-59 fsw maximum depth dives than do men, and while men have more 60+ fsw dives (depth stats are population normalized). Based upon this, Bob is more likely to at some point get DCS than Karen.

 

[Rhone Man]

Of all the diving accident stories that I have ever read, the one that scares me the most is the very first story in Diver Down by Mike Ange - story of an experience tec diving instructor who surfaces after a relatively shallow (60') dive, well within NDLs, and for reasons nobody fully understands, suffers some kind of DCI.

I'd put that one forward, except that I don't think anyone really knows exactly how it happened.

 

[Blackwood]

When I read that they "made a plan for maximum bottom time at depth" I interpreted this as NDL or an air volume limit. Either one, if followed, could lead to a problem given unforeseen circumstances during the profile.

Nit-picker.

I'm not being nit-picky, I just interpret it differently.

"You wanna go diving?"
"Sure. How long you wanna stay down?"
"How about 25 minutes?"
Checks are done to ensure said bottom time is reasonable.
"Sounds good, let's do it."



Perhaps it's a bad assumption in general that the italicized part is involved in that plan, but it's sound given the group I actively dive with.

I guess it's possible that the average diver will look at some (NDL) table and see 20 minutes at the end of the 100 foot entry and say "that's my planned maximum" with no other considerations given, but that's not my personal experience.

 

[LeadTurn_SD]

Interesting exercise.

While it sounds like the "Karen and Bob" are doing all the right things pre-dive, and have planned their dive to a level that is well beyond the "average" vacation diver, a few things stood out as potential "red flags".

1.) Wall dive. Although they have a planned depth of 100 feet, there is no physical barrier preventing them from descending beyond that depth accidently.

2.) Planned depth is 100 feet. They are either on air or nitrox... 100 feet is where many begin to experience narcosis. Narcosis + no bottom could be problematic if they don't have great buoyancy control.

3.) Hp100 tanks. It's nice to have that extra air.... but the extra air will give them enough extra time to get bent at the depth they are planning.

When I consider no bottom, narcosis, and enough gas to easily go beyond NDL, I can begin to see "accident waiting to happen" written on this dive unless "Karen and Bob" are really careful.

Best wishes.

 

[W8less]

Expanding on the envenomation issue even though Bob and Karen were respectful of the reef and kept their hands off, Bob got jellyfished and in his surprise, shock and unbearable pain he bolted. Karen tried to grab his fin as he rocketed but could not slow/stop him. She let him go. She found Bob on the surface in agony. Treatment was carried out although confused as the JF stings masked the DCS symptoms.

 

[Gombessa]

When I read that they "made a plan for maximum bottom time at depth" I interpreted this as NDL or an air volume limit. Either one, if followed, could lead to a problem given unforeseen circumstances during the profile.

Nit-picker.

I see what you're saying, but I don't think the context of the hypo lends that position much support:

"They look at the planned depth of 100ft....multilevel profile, coming up a wall. They compare that profile to their own gas consumption on their HP100 tanks, and conclude that this is a dive they can do. They make a plan for maximum bottom time at depth, and sketch out a desired profile."

If you hit NDL at your max depth on a recreational dive, you're coming up, not continuing on a multiprofile dive up a wall. I think this means what it sounds like, they make a plan to stay no longer than x time, which they determine to be their maximum, though they can always cut the deep part short (if something goes wrong, or if there is more interesting stuff higher up the water column that they'd rather spend time at) of their maximum.

Perhaps Lynne can respond and clarify, but I think the way the story is described supports Blackwood's reading.

 

[idocsteve]

Okay -- here's the challenge. Tell me what could happen (other than being eaten by a shark) that could cause a serious accident or fatality, given that the dive is executed as described.

I got another one.

The divers board the boat, and are joined by a solitary individual, an older fellow, who is only along to "watch bubbles". He doesn't say much to anyone, and some divers are troubled by the mans dishelved appearance and the fact that he's wearing a long trenchcoat on a relatively mild summer day.

Bob and Karen complete their dive with no problems as per their thorough predive planning, and they bask in the sun on the upper deck as they wait for the other divers to return to the boat.

Shortly thereafter, the last diver is aboard and the ladder is pulled, and the boat starts heading back to port when suddenly a commotion is heard on the lower deck.

"I hate all you divers you look like the aliens that abducted me when I was a child and planted things in my head!" Followed by the sounds of several shots and splashes as divers are tossed one by one into the ocean.

Bob looks at Karen and says "sssh..let's stay very quiet up here and maybe he won't find us".

Alas...Karen had grabbed her cellphone out of her dry bag following the dive, to tell a friend about her great vacation, and she got a call at just the wrong moment. The last sight those two careful divers saw was the psycho's head and the barrel of the rifle at the top of the ladder leading to the sun deck.

Two more splashes and all was quiet.

 

[Cave Diver]

I got another one.

The divers board the boat, and are joined by a solitary individual, an older fellow, who is only along to "watch bubbles". He doesn't say much to anyone, and some divers are troubled by the mans dishelved appearance and the fact that he's wearing a long trenchcoat on a relatively mild summer day.

Bob and Karen complete their dive with no problems as per their thorough predive planning, and they bask in the sun on the upper deck as they wait for the other divers to return to the boat.

Shortly thereafter, the last diver is aboard and the ladder is pulled, and the boat starts heading back to port when suddenly a commotion is heard on the lower deck.

"I hate all you divers you look like the aliens that abducted me when I was a child and planted things in my head!" Followed by the sounds of several shots and splashes as diver's are tossed one by one into the ocean.

Bob looks at Karen and says "sssh..let's stay very quiet up here and maybe he won't find us".

Alas...Karen had grabbed her cellphone out of her dry bag following the dive, to tell a friend about her great vacation, and she got a call at just the wrong moment. The last sight those two careful divers saw was the psyco's head and the barrel of the rifle at the top of the ladder leading to the sun deck.

Two more splashes and all was quiet.

Steve, your last name wouldnt happen to be "King" would it?

 

[idocsteve]

Steve, your last name wouldnt happen to be "King" would it?

I know, right?

I think I missed my calling

 

[vshearer]

What happened to the "group guide".?