Faith diving and magic?

[Jax]

@tesnusxenos: Depending on the experience level of the divers in your group, you may want to revise this part of your pre-dive briefing. Although it may work well for novice divers who have no idea how to plan a dive (gas, depth, etc.), I could see more experienced divers being a little put off by such a recommendation.

Best of luck with the rest of your DM training...

Would that not require the "more experience divers" to put their egos before their diving?

I would think - hope - the more experienced divers would simply dive their plan. Or am I being naive?

 

[Bubbletrubble]

Would that not require the "more experience divers" to put their egos before their diving?

@Jax: It has nothing to do with ego. It has everything to do with limiting a diver (paying customers, no less) unnecessarily. One important factor that influences my choice of dive op is the degree of freedom afforded its customers. I verify this before I go so far as to reserve a spot on the boat. Given the DM instructions described in a previous post, I'd be surprised and perhaps a little upset that the DM wasn't on the same page as the dive op. More specifically, I'm thinking about how I'd react to a relatively inexperienced DM (less than 50 dives) who instructed me to stay "above" him on a dive. Why is he requesting this? How do I know that the DM's computer is spitting out an acceptable level of NDL conservatism for my taste? It could be too conservative for my diving preferences. I've seen DMs who sawtooth up and down in the water column, which depending on the algorithm used may affect the NDLs on his computer. Also, if he's working several dives a day on consecutive days, his nitrogen loading status will almost certainly be very different than mine. Moreover, I'd be curious whether following the DM's instructions would prevent my dive team from executing our agreed-upon dive plan. Of course, I'd discuss all of this with the DM immediately following the pre-dive briefing so as to prevent any surprises underwater.

I would think - hope - the more experienced divers would simply dive their plan. Or am I being naive?

You're not being naive at all. I agree. All divers should plan their dive and execute that plan.

 

[DandyDon]

I simply dont use a dive computer. I use a dive watch. I know table bottom times off by heart so it helps! I dont do more than 2 dives a day. I would recommend having a dive computer though ! And i should get one soon

Yeah, one of the last boat trips on my last Cozumel trip, we had a couple of out of practice vacation divers, rental gear, no computers, simply following the DM. Well, we all did, but those of us with computers at least knew what we were getting into. It was a deeper, square bottom profile - unusual for Coz, got pretty loaded. We took a longer SI than usual in part because of everyone's loading, in part because we had the couple with no computers.

Our SS took longer than usual to clear yellow and get back into the green like we like to do before final ascent. We saw the couple blow off the SS and head for the surface. We got the DMs attention and he went up to bring them back down. It is better to know what's going on.

 

[Bubbletrubble]

Our SS took longer than usual to clear yellow and get back into the green like we like to do before final ascent. We saw the couple blow off the SS and head for the surface. We got the DMs attention and he went up to bring them back down. It is better to know what's going on.

@DandyDon: Did the DM weigh the potential harm of "bubble-pumping" against the loss of safety margin afforded by a safety stop? As you know, a safety stop is not required. Re-descending from the surface back to 15 fsw to complete a "missed" safety stop could possibly do more harm than good. I hope that the DM realized this. Sometimes people are blinded by what should have happened in the past rather than the best possible course of action in the present.

 

[lowviz]

.......I would think - hope - the more experienced divers would simply dive their plan. Or am I being naive?

Nah, on target. "Enjoying your dive" isn't made better by making others feel badly about themseves.

Intercepting stupidity is something on an entirely different level.

 

[bleeb]

@DandyDon: Did the DM weigh the potential harm of "bubble-pumping" against the loss of safety margin afforded by a safety stop? As you know, a safety stop is not required. Re-descending from the surface back to 15 fsw to complete a "missed" safety stop could possibly do more harm than good. I hope that the DM realized this. Sometimes people are blinded by what should have happened in the past rather than the best possible course of action in the present.

Not that I don't think this is a good point, but does anyone know of any way to compare the relative risk, even roughly? Or in the likely case that there's no data with which to compare the two scenarios, what subjective criteria might people use to make a choice?

 

[DandyDon]

@DandyDon: Did the DM weigh the potential harm of "bubble-pumping" against the loss of safety margin afforded by a safety stop? As you know, a safety stop is not required. Re-descending from the surface back to 15 fsw to complete a "missed" safety stop could possibly do more harm than good. I hope that the DM realized this. Sometimes people are blinded by what should have happened in the past rather than the best possible course of action in the present.

Oh, I didn't talk with the DM about it. He just did what DMs generally do at tourist destinations I think. Not the first time I've seen one retrieve a diver who missed a SS and bring him/her back down. Hitting the wrong button on the BC hose happens a lot.

When I first got certified, I read in a dive magazine that when a SS is missed, it's good to go back down and do a longer one, and I did just that on one of my first dives when I missed. I can see both sides of the issue tho.

These days, I go in with a general dive plan and a backup plan that covers how I ascend - slowly, stopped until in the green, then very slowly to surface after listening for motors, then look around prepared to sink if needed, gently to the ladder and gently up, easy on the boat, work at hydration, etc. carrying a 19 cf pony in case I need it, or anyone else around me.

I've also screwed, as recently as year before last - and was glad to complete a successful CESA while my pony was at the fill shack. :silly:

 

[Bubbletrubble]

Not that I don't think this is a good point, but does anyone know of any way to compare the relative risk, even roughly? Or in the likely case that there's no data with which to compare the two scenarios, what subjective criteria might people use to make a choice?

Off the top of my head, I can't cite any studies or quantitative evidence that might be helpful. However, there are other more practical things to consider. Take an inexperienced diver or buddy team that skipped a safety stop and is now at the surface.
If I were the DM in that scenario, I'd be asking the following questions:

• Why was the safety stop omitted?
• Was it due to a lack of attention, poor buoyancy control, under-weighting, or being cold?
• Was there a low gas supply issue?
• Was there a medical issue?
• What is the current mental state of the diver/divers in question (anxious, fatigued, etc.)?
• What are the chances that the diver/team can conduct a sufficiently long enough safety stop to make the trouble (and potential risk) of re-descending worth it?

Even if the dive team is capable of re-descending to do the missed safety stop, it may take a significant amount of time at the surface to make the proper gear adjustments (if necessary).

Once the DM considers all of these other factors, is it really worth it to re-descend to complete a missed safety stop?

If the DM were truly interested in increasing the dive team's safety margin, it would probably be best to place the dive team on O₂ at the surface and have them sit out on subsequent dives for the rest of the day.

 

[DandyDon]

Sounds like a better approach, Bubbletrubble - but I have to wonder how much of that a Cozumel DM is going to know, to mess with, etc. It would have helped if he could have looked at computers on them. One of the reasons I got a second dive computer is so that if I get a boat pick bud who doesn't mind, I can strap it to his BC and check it periodically - as he wouldn't know what it said anyway.

 

[Ayisha]

@tesnusxenos: Depending on the experience level of the divers in your group, you may want to revise this part of your pre-dive briefing. Although it may work well for novice divers who have no idea how to plan a dive (gas, depth, etc.), I could see more experienced divers being a little put off by such a recommendation.

Would that not require the "more experience divers" to put their egos before their diving?

I would think - hope - the more experienced divers would simply dive their plan. Or am I being naive?

I think that's what Bubbletrouble may mean. The more experienced divers intend to dive their own plan, not follow the DM's plan.