Accident & Incident Discussion - Northernone - aka Cameron Donaldson

[JohnnyC]

To which comment? Why is 130 Feet the Depth Limit for Recreational Scuba Diving?

What @mtngoat2674 said. There are at least two major certification agencies that have recreational levels in excess of 40m.

Using an arbitrary depth limit to discern a recreational dive from a technical dive falls apart pretty quickly.

Neither of your assertions are accurate. 130+ feet doesn’t mean it’s a technical dive, and in the absence of this fact, your second assertion can not be true. If there is nothing preventing a direct ascent or the surface, it is not a technical dive. And by simply varying the settings of the algorithm you are using to determine no-decompression limits and/or stops, you can quite easily turn a recreational dive into one requiring decompression stops, or alternatively, turn a dive requiring mandatory decompression into one with no required stops.

But we’re getting off topic, hence the brevity of my previous post.

 

[Protondecay123]

What @mtngoat2674 said. There are at least two major certification agencies that have recreational levels in excess of 40m.

Using an arbitrary depth limit to discern a recreational dive from a technical dive falls apart pretty quickly.

Neither of your assertions are accurate. 130+ feet doesn’t mean it’s a technical dive, and in the absence of this fact, your second assertion can not be true. If there is nothing preventing a direct ascent or the surface, it is not a technical dive. And by simply varying the settings of the algorithm you are using to determine no-decompression limits and/or stops, you can quite easily turn a recreational dive into one requiring decompression stops, or alternatively, turn a dive requiring mandatory decompression into one with no required stops.

But we’re getting off topic, hence the brevity of my previous post.

So the plan was 5-10 minutes at 120-150 ft. 10 minutes at 150ft puts you into decompression according to the NAUI tables I have. 10 minutes at 120 doesn’t. And 130 isn’t arbitrary the USN picked that depth because with the tables you could spend 10 minutes and not have a decompression obligation.

 

[JohnnyC]

So the plan was 5-10 minutes at 120-150 ft. 10 minutes at 150ft puts you into decompression according to the NAUI tables I have. 10 minutes at 120 doesn’t. And 130 isn’t arbitrary the USN picked that depth because with the tables you could spend 10 minutes and not have a decompression obligation.

You are making assumptions based on a limited data set and using them to make a generalization that covers the entirety of the world of diving. Navy divers are not recreational scuba divers, NAUI is not the only certifying agency, nor are their tables the only ones in the scuba diving world. The algorithm that NAUI is basing its tables on is not the only decompression algorithm safely and successfully used for dive planning, and tables are not representative of the way the VAST majority of people dive.

Without drifting further off topic, your assertions are false. Several agencies have arbitrarily decided that, for their purposes, 130ft/40m is where THEY draw the line for recreational scuba diving as they choose to define it. That does not make it a definitive truth, nor is it indicative of other agencies guidelines, or is it indicative of how physiology actually works in relation to decompression science.

 

[Dan]

If a diver has accrued 30 minutes of true deco and he makes a rapid OOG ascent, what do you think the result will be?

I don't know the answer, and don't know anyone who has done it, but my gut feeling is that a diver could easily be paralyzed. A 30 plus minute deco negates the surface as a safe place.

If a diver was being supported by a boat and the boat reached him immediately and the diver was provided a deco tank and was able to re-descend, then the out come might be better. A diver with an accrued penalty of 30 minutes, is really in a precarious and vulnerable position if he is alone.

I think it is reasonable to assume that something unusual happened. He had apparently done the dive many times, but if the current really was 6 knots as someone mentioned, there is not much a diver can do with that if it starts going in an undesirable direction- this also makes them vulnerable.

When we were in Raja Ampat, our DM would always check the current first before letting us enter the water. Anything greater than 2 knots, we'd go to another sites. If it's 6 knots, forget it. There are plenty of better & calmer sites there just around the corner.

 

[mtngoat2674]

You are making assumptions based on a limited data set and using them to make a generalization that covers the entirety of the world of diving. Navy divers are not recreational scuba divers, NAUI is not the only certifying agency, nor are their tables the only ones in the scuba diving world. The algorithm that NAUI is basing its tables on is not the only decompression algorithm safely and successfully used for dive planning, and tables are not representative of the way the VAST majority of people dive.

Without drifting further off topic, your assertions are false. Several agencies have arbitrarily decided that, for their purposes, 130ft/40m is where THEY draw the line for recreational scuba diving as they choose to define it. That does not make it a definitive truth, nor is it indicative of other agencies guidelines, or is it indicative of how physiology actually works in relation to decompression science.

Well said. There are any schools of thought on appropriate algorithms, and the grand majority of them are less conservative than any of the tables used by major certifying agencies. Regardless, extended range diving is not especially technical or complicated, provided one has the experience in dealing with the equipment necessary to carry sufficient gas.

Obviously opinions vary regarding solo diving in both the recreational and tech world, but regardless how you view that (and whether or not depth plays into the opinion on which he might have been engaged in), Cameron was experienced with both. We commiserated regularly on long duration dives (at varying depths), both OC and rebreather.

 

[Dan]

What @mtngoat2674 said. There are at least two major certification agencies that have recreational levels in excess of 40m.

Using an arbitrary depth limit to discern a recreational dive from a technical dive falls apart pretty quickly.

Neither of your assertions are accurate. 130+ feet doesn’t mean it’s a technical dive, and in the absence of this fact, your second assertion can not be true. If there is nothing preventing a direct ascent or the surface, it is not a technical dive. And by simply varying the settings of the algorithm you are using to determine no-decompression limits and/or stops, you can quite easily turn a recreational dive into one requiring decompression stops, or alternatively, turn a dive requiring mandatory decompression into one with no required stops.

But we’re getting off topic, hence the brevity of my previous post.

Whatever ways you justify the dive limit, diving down to 130-50' deep solo, after 40 min diving in, say 70' deep, doesn't sound like a safe dive plan to me.

 

[scubadada]

We have no idea what Cameron's profile was after he left his mother.

 

[ggunn]

What @mtngoat2674 said. There are at least two major certification agencies that have recreational levels in excess of 40m.

Using an arbitrary depth limit to discern a recreational dive from a technical dive falls apart pretty quickly.

Neither of your assertions are accurate. 130+ feet doesn’t mean it’s a technical dive, and in the absence of this fact, your second assertion can not be true. If there is nothing preventing a direct ascent or the surface, it is not a technical dive. And by simply varying the settings of the algorithm you are using to determine no-decompression limits and/or stops, you can quite easily turn a recreational dive into one requiring decompression stops, or alternatively, turn a dive requiring mandatory decompression into one with no required stops.

But we’re getting off topic, hence the brevity of my previous post.

Does DAN have any limits to the depth a diver can dive and still be covered by their insurance?

 

[abnfrog]

johnyc just so you know 130 was not arbitrary 130 is 3.8 ata of n2 at 4 ata absolute of nitrogen they (not sure who ) said that all diver are impaired to a degree (bill Hamilton told me that years ago and I belive him ) maybe sam miller can add to this im sure he knows

 

[tursiops]

Does DAN have any limits to the depth a diver can dive and still be covered by their insurance?

The Guardian (most expensive) policy has no depth limit. The cheaper ones do. See the DAN website for details.