Fiona Sharp death in Bonaire

[Wookie]

I was Fiona's dive buddy a few years ago in Truk.

Until there is a formal explanation from a statutory authority kindly refrain from discussing it on the Internet.

Freedom of speech is a core value we all enjoy in most parts of the world, however, out of respect for someone who was known and well liked by numerous people worldwide in the technical diving & medical fields, please take a safety stop.

This is good source of information to discover what happened which will be updated in due time

Deep Life Design Team: databases and analysis of rebreather accident data

Any replies to my posting WILL NOT BE READ.

Welcome to ScubaBoard.

 

[OceanEyes]

I'm similarly curious - do any rebreather models have some sort of external indicator of their status that a buddy could monitor from a distance? Some of the failure modes sound like they can exhibit pretty subtly in the user unless there are active checks being performed on a regular basis.

(Obviously there is a lot of data that determines an 'ok' state - which is why I'm curious...)

Hello @Mike Walker.

There are ways that one diver may be able to monitor the PO2 of another, and thus be able to determine whether the second diver is at risk of having too much or too little oxygen in their loop. One method is to read the other diver’s handset or computer which should display the PO2 in the loop. This is not always practical unless the divers are extremely close to each other and visibility is sufficient to read the information at a given distance.

A simple method is to have arranged a signal among a team which inquires “what is your PO2?”, and like an “Okay” sign, demands a reply. This may not be effective however if the replying diver is disoriented for any reason, as the reply may or may not be accurate.

There is a means of reading another diver’s display from a distance, but this requires that diver A, the observer, is well acquainted with diver B’s rig, in particular of the means of interpreting the information conveyed by diver B’s HUD, heads up display.

HUDs are nearly universal equipment on CCRs that have been produced for civilian use for many years now, and are simply small electronic displays wired to the unit’s O2 sensors, mounted near one of the diver’s eyes, which provide the diver with information regarding the PO2 present in the loop. Some of these displays are very simple, consisting of a single LED that flashes in a prescribed manner which reflects the PO2. Others are much more complex like the Shearwater NERD which conveys as much information as the sophisticated dive computer that in fact it is.

There is however no universal protocol among CCR manufacturers and how their HUD’s convey information. Thus in order for diver A to know what diver B’s HUD is indicating, diver A must be thoroughly familiar with diver B’s unit. For example, if you were diving with me and wished to understand my HUD, you would have to be familiar with the simple ISC single LED HUD protocol. This HUD features a single bulb which changes color and flashes or blinks at specified intervals to indicate the PO2 in the loop. A simple breakdown of this HUD is as follows:

Red
Continuous blinking less than 0.5 PO2 Hypoxic
5 short blinks/pause/5blinks 0.5 PO2
4 short blinks/pause/4 blinks 0.6 PO2
3 short blinks/pause/3 blinks 0.7 PO2
2 short blinks/pause/2 blinks 0.8 PO2
1 short blink/pause/1 blink 0.9 PO2
Yellow
1 short blink/pause/1 blink 1.0 PO2
Green
1 short blink/pause/1 blink 1.1 PO2
2 short blinks/pause/5 blinks 1.2 PO2
3 short blinks/pause/3 blinks 1.3 PO2
4 short blinks/pause/4 blinks 1.4 PO2
5 short blinks/pause/5 blinks 1.5 PO2
Continuous blinking greater than 1.5 PO2 Hyperoxic

The ISC HUD is not extremely bright, though sufficient for me to read in all but the brightest sunshine at very shallow depth in clear water. It would be more of a challenge for you read my HUD, but not impossible. As I keep my HUD directed at my eye at about a 45% angle, you may be able to read the flashes if we are close enough on a bright day, or even read the reflected flashes off of my mask. At greater depth, or in an overhead environment it would be a bit easier for you to see my display flashing.

 

[divezonescuba]

If this was off of Buddy / Bari reef, you have to go a really long way towards Klein to get to 300 ft. The bottom of the first reef is 140 or so and the sand flat towards Klein is very gradual.

IIRC, Andre the BDA guy told me that the second reef is at that depth.

 

[doctormike]

Hello @Mike Walker.

There are ways that one diver may be able to monitor the PO2 of another, and thus be able to determine whether the second diver is at risk of having too much or too little oxygen in their loop. One method is to read the other diver’s handset or computer which should display the PO2 in the loop. This is not always practical unless the divers are extremely close to each other and visibility is sufficient to read the information at a given distance.

A simple method is to have arranged a signal among a team which inquires “what is your PO2?”, and like an “Okay” sign, demands a reply. This may not be effective however if the replying diver is disoriented for any reason, as the reply may or may not be accurate.

There is a means of reading another diver’s display from a distance, but this requires that diver A, the observer, is well acquainted with diver B’s rig, in particular of the means of interpreting the information conveyed by diver B’s HUD, heads up display.

HUDs are nearly universal equipment on CCRs that have been produced for civilian use for many years now, and are simply small electronic displays wired to the unit’s O2 sensors, mounted near one of the diver’s eyes, which provide the diver with information regarding the PO2 present in the loop. Some of these displays are very simple, consisting of a single LED that flashes in a prescribed manner which reflects the PO2. Others are much more complex like the Shearwater NERD which conveys as much information as the sophisticated dive computer that in fact it is.

There is however no universal protocol among CCR manufacturers and how their HUD’s convey information. Thus in order for diver A to know what diver B’s HUD is indicating, diver A must be thoroughly familiar with diver B’s unit. For example, if you were diving with me and wished to understand my HUD, you would have to be familiar with the simple ISC single LED HUD protocol. This HUD features a single bulb which changes color and flashes or blinks at specified intervals to indicate the PO2 in the loop. A simple breakdown of this HUD is as follows:

Red
Continuous blinking less than 0.5 PO2 Hypoxic
5 short blinks/pause/5blinks 0.5 PO2
4 short blinks/pause/4 blinks 0.6 PO2
3 short blinks/pause/3 blinks 0.7 PO2
2 short blinks/pause/2 blinks 0.8 PO2
1 short blink/pause/1 blink 0.9 PO2
Yellow
1 short blink/pause/1 blink 1.0 PO2
Green
1 short blink/pause/1 blink 1.1 PO2
2 short blinks/pause/5 blinks 1.2 PO2
3 short blinks/pause/3 blinks 1.3 PO2
4 short blinks/pause/4 blinks 1.4 PO2
5 short blinks/pause/5 blinks 1.5 PO2
Continuous blinking greater than 1.5 PO2 Hyperoxic

The ISC HUD is not extremely bright, though sufficient for me to read in all but the brightest sunshine at very shallow depth in clear water. It would be more of a challenge for you read my HUD, but not impossible. As I keep my HUD directed at my eye at about a 45% angle, you may be able to read the flashes if we are close enough on a bright day, or even read the reflected flashes off of my mask. At greater depth, or in an overhead environment it would be a bit easier for you to see my display flashing.

I agree that hand signals to communicate PO2 when necessary is a good idea. But I think that having your buddy actually monitor your PO2 within the breathable range is not relevant. Assuming that we are talking about two certified rebreather divers, expecting a buddy to actually monitor another diver's PO2 throughout the dive is not reasonable.

Unless you are talking about an instructor watching another student's PO2, the only thing that a "buddy light" needs to do is to alert a buddy that the diver is getting an alert (i.e out of the preset range of breathable PO2). So your buddy doesn't need to read the Smither's code and figure out what your PO2 is. They just need to be alerted that YOU are getting an alert. Then they need to confirm that you are appropriately responsive and have seen the alert. That's the idea behind - for example - the buddy light on the Meg or the JJ HUD:

 

[Mike Walker]

OceanEyes

doctormike

Interesting - I'd perceived it as likley too complex to sum up with a single indicator, but it seems at least 2 manufacturers already do this. Anyways, diverging a bit from the core topic but it is useful to help those of us who don't run into many rebreathers understand what degree of automation and sensing is present in current generation systems. Thanks.

 

[doctormike]

Interesting - I'd perceived it as likley too complex to sum up with a single indicator, but it seems at least 2 manufacturers already do this. Anyways, diverging a bit from the core topic but it is useful to help those of us who don't run into many rebreathers understand what degree of automation and sensing is present in current generation systems. Thanks.

Sure!

The rebreather A&I threads (sadly, a significant number of them) often are simply not understandable to the majority of the non-CCR divers who read them without these explanations. I know that we are supposed to stay "on topic" but much of the discussion doesn't make sense without some basic understanding of these units.

 

[ChuckP]

Wow, incredibly sad. Condolences to family, friends and colleagues.

I wonder if she had a typical type gas profile she would dive for those conditions and what it was?

 

[seaseadee]

Sure!

The rebreather A&I threads (sadly, a significant number of them) often are simply not understandable to the majority of the non-CCR divers who read them without these explanations. I know that we are supposed to stay "on topic" but much of the discussion doesn't make sense without some basic understanding of these units.

This has been very helpful in understanding the basics of how they function:
Rebreathers Guide for beginners: advantages, how it works, training
edit: and
Rebreather Safety & Bailout Procedures | AP Diving

 

[JohnnyC]

I was Fiona's dive buddy a few years ago in Truk.

Until there is a formal explanation from a statutory authority kindly refrain from discussing it on the Internet.

Freedom of speech is a core value we all enjoy in most parts of the world, however, out of respect for someone who was known and well liked by numerous people worldwide in the technical diving & medical fields, please take a safety stop.

This is good source of information to discover what happened which will be updated in due time

Deep Life Design Team: databases and analysis of rebreather accident data

Any replies to my posting WILL NOT BE READ.

Kindly refrain from reposting that piece of trash, fraudulent, utterly ******** piece of “research” on this site.

Reply if you want. I’d be more than happy to take part in a discussion.

 

[silent running]

I was Fiona's dive buddy a few years ago in Truk.

Until there is a formal explanation from a statutory authority kindly refrain from discussing it on the Internet.

Freedom of speech is a core value we all enjoy in most parts of the world, however, out of respect for someone who was known and well liked by numerous people worldwide in the technical diving & medical fields, please take a safety stop.

This is good source of information to discover what happened which will be updated in due time

Deep Life Design Team: databases and analysis of rebreather accident data

Any replies to my posting WILL NOT BE READ.

Way to go, your last line tells us everything we need to know about your respect for free speech, and the dialogue necessary to actually get the benefit of it.

Your respect for the “formal” and “statutory” is misplaced and not consistent with the idea of free speech in any event.