Dives and dive time

[DevonDiver]

Maybe. Or they could plan a dive such that their precautionary stop is completed within the allotted time.

This is true... but I bet if we compared watches right now there's be a few minutes difference.

Allegedly, the OP was only a couple of minutes behind the group, because he and his buddy elected to perform the agency recommended safety stop.

Maybe he (reasonably) assumed the whole group would do a safety stop...and was then surprised when they ascended directly to the surface. I would reasonably assume that a safety stop would be done, unless clearly briefed otherwise.

Even then.. we're talking about 2 minutes extra (I think?)... which would mean the main group would still be taking their fins off, climbing the ladder etc....

Or was it much longer than 2 minutes??

 

[dmcutter]

I was in Aruba at the beginning of December and went out 3 days with one of the local outfitters. Being a newb I was a little nervous, especially since it was my first ocean diving. The DM briefed us on the dive and I asked about safety stops, as did several other much more experienced divers. The DM said we would descend to the planned depth and slowly ascend along the reef so we would not need to make a stop, 40 minute dive time.

On the second day, first dive, I was short on air (tank started at about 2800 psi) and when my computer told me I had only 3 minutes of air I opted to use that for my safety stop, which I did by myself. I ended up surfacing a goodly distance away from the boat becasue I didn't take the current into account when I made my stop so I swam back by myself. My DM did not deride me for making a safety stop, nor did he make a fuss about my surfacing far away from the boat. The boat crew said they saw me but couldn't come get me because everyone was under the boat. Maybe they were doing a safety stop en masse? Of the 6 dives I did with them, don't remember any other discrete safety stops.

 

[Blackwood]

This is true... but I bet if we compared watches right now there's be a few minutes difference.

Most likely. Like I said back in post 46, you'll find that between two of my watches, let between alone mine and yours.

Maybe he (reasonably) assumed the whole group would do a safety stop...and was then surprised when they ascended directly to the surface.

I would say that's an unreasonable assumption given that "before this dive, during the briefing, he told everyone, "when I give you the signal to get out of the water you need to do it then.""

I would reasonably assume that a safety stop would be done, unless clearly briefed otherwise.

Agreed. I'd have taken the above bolded statement as clear direction to get out of the water when instructed, and would have accordingly planned my dive including whatever stops I saw fit. As I suggested before, it's possible that maximum run time wasn't briefed, in which case everyone was planning with incomplete direction (which should have been given, and should have been demanded if not given).

The main problems are
1. This was planned as a 'follow the leader' dive ("These two dives where planned by the dive boat"), and
2. The OP neither followed the leader nor made an appropriate plan to dive independently.

Even then.. we're talking about 2 minutes extra (I think?)... which would mean the main group would still be taking their fins off, climbing the ladder etc....

I surmise that they wanted everyone to be on the surface together before the boat approached.

Or was it much longer than 2 minutes??

I don't think the OP has stated how long the stop they aborted would have been.

 

[boulderjohn]

Just a quick point--this happened in Aruba.

What does that have to do with it?

When i went to Aruba, I scouted operators very carefully via SB. I found out that a lot of them run a very tight schedule. I got an operator who did not and who allowed the divers the full use of their own planning, but I had to use one of the other operators one day. When we got to the dock for our scheduled departure time, the boat was not there. It came in finally and we had to do a very hurried boarding process to get get back on schedule. The people running the shop were clearly upset, and the crew coming in had to do some explaining about why they were late. We went out and followed a very rigid dive plan to get the boat back on schedule.

If the boat and DM were one of those operators, that is probably why there was so much pressure to get divers out of the water. Getting back a few minutes late would get that boat crew in trouble for screwing up the schedule.

 

[rivers]

This is true... but I bet if we compared watches right now there's be a few minutes difference.

The OP stated that he was diving with a computer. Every computer I have seen states the "dive time" somewhere on the watch (but I have only seen a handful of computers so maybe on other computers you have to scroll through the screens to get dive time).
And from the sounds of it, both dives were a "follow the leader" type dive, which means they all would have entered the water one after the other (in my experiences the DM would be last), and descended together, with the dives starting within seconds of each other.

 

[hg frogman]

Personally, I always do an hour SI to help off gas. I know if you use Nitrox you can do shorter SI's, but I like to play it safe. I'm not willing to push it and risk getting DCS.

PADI Nitrox specialty course recommends at least one hour of surface interval between two dives (because of oxygen toxicity ; according to the PADI Enriched Air Diver Specialty Course Instructor Outline).

Generally speaking, short surface intervals (i.e. only one hour or even less) significantly increase the risk of DCS (either with air or Nitrox). That's partly why I think that two-tanks dives suck.

Spinal DCS is far from uncommon (*) and usually hits after the second or third dive of the day (*) (but of course the previous dives are often triggering it). Especially if these dives get close to the (edit) NDL (end edit). All the more if the divers are dehydrated, aged 40 or more, etc ...

Edit : (*) Statistics from the French Federation (FFESSM). The majority of type II (neurological) DCS hits are spinal ones in France. Of course if one does four short (e.g. 30 minutes) and shallow (e.g. first dive 12 meters, second 10 meters, others 9 meters or less) dives a day, with proper ascent rates, DCS isn't a big concern, even with short SI's. That's typical of diving in some places. But on the other hand, if the dives stretch towards the 30 meters area (that was the case of the OP, BTW) or beyond, then surface interval duration becomes a very important factor. And in many places the 30 meters zone is very interesting.

 

[DevonDiver]

I would say that's an unreasonable assumption given that "before this dive, during the briefing, he told everyone, "when I give you the signal to get out of the water you need to do it then.""

Fair enough. At that time... it was the responsibility of the diver concerned to stick his mitt in the air and say "what is the protocol if I wish to do a safety stop on my ascent?"

I don't think the OP has stated how long the stop they aborted would have been.

From his first post... he showed that he completed 2 mins of safety stop. He called it a safety stop... so I am assuming that it was a 3 min stop. I am confused about the deco issue though. However, given his stated dive profiles, I don't see how he could have accrued any substantial deco..?

 

[rivers]

I think the assumption is his buddy's computer went into deco as he stated his buddy had a 5 minute stop and the computer was beeping when he surfaced. It is possible the buddy's computer was not reset as it was a rental.... There's still a lot we are of unsure in this given situation, and there is much speculation and discussion.

 

[Blackwood]

Fair enough. At that time... it was the responsibility of the diver concerned to stick his mitt in the air and say "what is the protocol if I wish to do a safety stop on my ascent?"

Bingo!

From his first post... he showed that he completed 2 mins of safety stop. He called it a safety stop... so I am assuming that it was a 3 min stop. I am confused about the deco issue though. However, given his stated dive profiles, I don't see how he could have accrued any substantial deco..?

As rivers pointed out, I'm wrong, he did state a duration: his buddy's computer wanted 5 minutes.

 

[DevonDiver]

The DM said we would descend to the planned depth and slowly ascend along the reef so we would not need to make a stop, 40 minute dive time.

Only if the DM was psychic...and knew how much diving you'd done in the days prior to that trip...and whether he could see into the future and know with certainty that you wouldn't accidentally exceed your ascent rate... and if he'd completed a full medical check on you and could guarantee that you didn't suffer from any DCS pre-disposing conditions that would make a safety stop more important...

Besides which... you might not need to conduct a safety stop... but you might want to conduct one. It is your right to do one if you want to.

Just make sure you communicate that at the time of the briefing...and not at the end of the dive.

I found out that a lot of them run a very tight schedule. .....If the boat and DM were one of those operators, that is probably why there was so much pressure to get divers out of the water. Getting back a few minutes late would get that boat crew in trouble for screwing up the schedule.

That's a dive shop issue... not a customer issue. If my safety was put second to the convenience of the shop's scheduling, then I wouldn't be diving with them again.

If I got shouted at, because I delayed the boat by 5-10 minutes, then I'd be having a very frank and firm discussion with the dive centre manager upon my return.

Quite simply... I would not pay my hard earned money to dive with a monkey outfit that acted like that.