Feature request for rebreather HUD

[tbone1004]

@doctormike keep in mind with the Shearwater recall, it was never a functionality issue. The yellow transmitters were supposed to broadcast at a different interval than the grey ones to minimize risk of them broadcasting simultaneously and causing a communication overlap. Unfortunately the manufacturer didn't actually make them with the different interval, so they got called back to fix. I think it was 5sec on the grey, supposed to be 7sec on the yellow.

on the buddy light. I don't think a light on the HUD is going to do anything productive. On the top of the unit itself maybe, but don't think a buddy light would be big, bright, or obvious enough to get any meaningful data from

 

[doctormike]

Maybe it’s more about cave diving, with some caves are more of a roller coaster, like peacock.. but I like to keep my eye on my DIL. With shoulder mounted CLs.. seeing my gauges is not as easy as I would like. I’m am planning to add the AI transmitters to the Nerd2 at some point.

Yeah, I guess. I don't know much about cave diving. So how do you plan a cave dive, then? Do you watch your dil and do rule of thirds or something? In the ocean, a little goes a long way...

 

[doctormike]

The link doesn't work.

The only French study I remember wasn't looking at the efficacy of buddy awareness as much as it was the efficacy of maintaining the divers airway through the use of either a gag strap or FFM. The idea being that when you DO have an issue, preventing drowning by keeping the loop in your mouth gave you a much higher chance of survival.

Here you go, see if the attached PDF works.

I don't have the raw data, but this from the article:

"Overall, these gas toxicities–related disorders were pre- dominantly observed in student divers (67 cases out 104, ie, 64%) and resulted in an impairment of consciousness in 54 cases out of 104 (52%), with 11 cases related to severe hypercapnia. Outcome was always favorable once the injured diver was rescued by his buddy to be brought back to the sur- face and disconnected from his breathing apparatus. However, 2 cases with moderate water aspiration were noted follow- ing a case of hypercapnia and 1 of hyperoxia. Regarding the specific disorders encountered by each sub-population of divers, the IRR for MCD vs. CS were as follows: 0.6 (95% CI: 0.3, 1.1) for hypercapnia, 0.2 (95% CI: 0.1, 0.5) for hyper- oxia and 1.5 (95% CI: 0.4, 5.3) for hypoxia."

I would bet that even with a gag strap or FFM, recovery of consciousness to the point of being able to surface safely without a buddy would be a pretty unusual occurrence.

 

[doctormike]

on the buddy light. I don't think a light on the HUD is going to do anything productive. On the top of the unit itself maybe, but don't think a buddy light would be big, bright, or obvious enough to get any meaningful data from

What do you mean? It only has to communicate one bit of information: Alert or no alert. Normally it's not lit, so if you see your buddy's HUD light up, you could check them out and not just assume that he or she is capable of flying their CCR safely. A diver who is distracted or impaired (from hypoxia, hyperoxia or hypercapnea) might not be responding to an alert.

I don't have experience with a lot of different units, but my stock JJ HUD has a buddy light, and it looks like the HUD for the ISC Tiburon and the Prism 2 have the same design.

 

[JohnnyC]

One of the problems with a buddy light is that it can’t just be on or off, it needs to be on and “safe,” or on and “unsafe.” If it’s off, you have no way of knowing if it’s working, you just know that it’s not alarming. But it also won’t alarm if it’s broken, so unless there’s some verification that it’s functional, you can’t trust that it’s working.

So what’s the solution? Well, it needs to be on all the time. Say, green or flashing red, safe or unsafe. Ok, so we’ve got a scheme that positively shows a working state, and an alarm state. Now, how do we make it unobtrusive until there’s an issue? How do we accomplish that, but still be useful by being visible by your buddy from any direction, position, or orientation? We start running into issues where it’s becoming intrusive when we don’t want it to be. You’d need indicators all over the unit, and they always have to be visible. You’d look like a different kind of Christmas tree.

If you look in the video, the buddy noticed the alarm state on the guys Predator. I think perhaps a better alarm state would be a change in how a Shearwater shows an alarm. Maybe flash the whole screen in red at full brightness until safe or switched to bailout. Enough off time to still display information, or maybe leave depth visible, but make it impossible to miss on the handset? I don’t know, it’s a fine line that I don’t have the answer to. I think the idea of a buddy light has merit, but the implementation is a tough nut to crack.

 

[Caveeagle]

Yeah, I guess. I don't know much about cave diving. So how do you plan a cave dive, then? Do you watch your dil and do rule of thirds or something? In the ocean, a little goes a long way...

Well, In interests of full disclosure, I am taking my “cave-CCR” cross over training this weekend, so I can only tell you what I have been doing. And yes, I have uses a “3rds” rule as a safe turn point, but I think that has been very conservative considering i have LP hoses on both bailout bottled and could switch to off board dil, if it really came down to it.

I will say that my Dil consumption had improved greatly, but I do try to do a quick check every 10-15m just to make sure my brain is still working. FWIW..know a CCR diver that blew through his DIL in the Peacock system, just half way through the planned dive. I didn’t really pry into root cause, as proper bail out and turning the dive allowed for a safe exit. I am certainly not the most experienced CCR diver, so I still try to err on being overly conservative.

 

[loosenit2]

It is interesting some of the developments that are occurring in dive computers. Several manufactures had added LED lights to the transmitters to indicate PSI windows (mares, Ratio). I have seen stories of the Oceans S1 Supersonic under development that allows units to "ping" each other get buddies attention. So it seems like the next wave of development (besides color screens) might be underwater non-verbal communications.

I've never used a NERD but it would seem you would have to be in a very specific location to see a light on the outside of your buddies HUD. The transmitter lights tend to be pretty big but have the same basic issue, you have to be in the field of view for it to work.

I would welcome the development of more underwater communication capability in dive computers, but I wonder what that would do to the size of them. To be able to type you have to have a slightly larger screen, unless it uses pre-set texts that you could do, like selecting icons (i.e. apple watch). Transmit distance is also something that is a factor, fundamentally you have to increase power supply to increase range, so with existing batteries you would either have to recharge more frequently or put in bigger batteries (assuming of course no one invents new battery technology; where is Tony Stark when you need him?).

 

[doctormike]

I've never used a NERD but it would seem you would have to be in a very specific location to see a light on the outside of your buddies HUD. The transmitter lights tend to be pretty big but have the same basic issue, you have to be in the field of view for it to work.

I think that you are overthinking the buddy light concept. I don't know if you are a CCR dive, so forgive me if I'm overexplaining!

The way that it is currently implemented in many HUDs (the standard LED Smithers code models) is that the HUD is a little cylinder in front of the divers mask, that blinks LEDs that are facing the diver to show PO2 from each sensor. The buddy light is just one more LED on the end of the cylinder. It's just one additional LED, doesn't really draw a significant amount of extra power, doesn't change the size of the HUD, it only goes on if there is an alarm, and if you can see your buddy's face, you can see that LED. It's not implemented on the NERD, but if I were designing it, it would just be on the back of the housing, where anyone seeing the diver's face could see the LED.

Here is what the current implementation of a buddy light looks like on conventional HUDs:

 

[doctormike]

One of the problems with a buddy light is that it can’t just be on or off, it needs to be on and “safe,” or on and “unsafe.” If it’s off, you have no way of knowing if it’s working, you just know that it’s not alarming. But it also won’t alarm if it’s broken, so unless there’s some verification that it’s functional, you can’t trust that it’s working.

So what’s the solution? Well, it needs to be on all the time. Say, green or flashing red, safe or unsafe. Ok, so we’ve got a scheme that positively shows a working state, and an alarm state. Now, how do we make it unobtrusive until there’s an issue? How do we accomplish that, but still be useful by being visible by your buddy from any direction, position, or orientation? We start running into issues where it’s becoming intrusive when we don’t want it to be. You’d need indicators all over the unit, and they always have to be visible. You’d look like a different kind of Christmas tree.

If you look in the video, the buddy noticed the alarm state on the guys Predator. I think perhaps a better alarm state would be a change in how a Shearwater shows an alarm. Maybe flash the whole screen in red at full brightness until safe or switched to bailout. Enough off time to still display information, or maybe leave depth visible, but make it impossible to miss on the handset? I don’t know, it’s a fine line that I don’t have the answer to. I think the idea of a buddy light has merit, but the implementation is a tough nut to crack.

I generally defer to your experience, but I don’t agree with you on this one.

Are you saying that it should be on as either green or red at all times so that you know that it’s working? If you are postulating a buddy light failure, then the red mode could still fail independently.

It’s not like it’s the primary way of monitoring PO2 and needs a backup. It’s just one more tiny, unobtrusive, relatively cheap thing that - in the rare case of an impaired diver who is still on the loop - gives one more option for survival. If it fails independently, then you are just back in the same situation that most divers are now, no buddy light.

Why do you need indicators all over your unit? The ones that they have now are just on the HUD itself, and easily visible to anyone who can see the diver’s face, from any angle. Does the fact that they wouldn’t work if you were behind the diver make their primary benefit less? I suppose you could also have one on your back, or you could even have a transmitter that would sends your alert to your buddy’s HUD, but that’s just feature creep that doesn’t negate the benefit of something basic and simple. Why does the request for a buddy light on a NERD imply that you need to turn the diver into a Christmas tree?

If you think that it’s not worth it unless it’s configured to always be displaying green unless there is an alert, then aren’t you planning for three failures? (1) PO2 out of range, (2) impaired diver, and (3) failed buddy light.

And if you make that buddy alert part of a wrist mounted controller, then you WOULD be restricting the buddy’s ability to see it if the display wasn’t pointed outward. And you would be changing the controller display, which means that every time there was an alert, the non-impaired diver’s input would be altered. Where they are now (on the outside of the HUD) makes them pretty easy to see, and unobtrusive for everyone involved.

 

[Caveeagle]

I've never used a NERD but it would seem you would have to be in a very specific location to see a light on the outside of your buddies HUD. The transmitter lights tend to be pretty big but have the same basic issue, you have to be in the field of view for it to work.

I know this is not a cave specific thread, but... My buddies and I tend to stay in pretty constant communication through primary light signaling and awareness. The following diver should generally keep his/her spot pretty close to the halo of the lead diver. If I go more than a couple seconds without seeing my buddies light, I will cover my light and look for a quick light to pan back. Of course a circle signal, means ok, and a back and forth signal means not ok. No response means I better see what’s up. (I know this is pretty basic for some..)

Whenever I dive with an open circuit buddy, I explain what the red “buddy light” on my HUD means. So if they should ever wonder if I am ok.. they should know that a red LED means I should be bailing out.

I have been in the water with a buddy who was having issues that might have been a mild panic attack. In that case, on open circuit. But can really see the benefit for a buddy to have a quick reference alert, right by the face to confirm the safety of the breathing loop.

Just my opinion, but I think this would be a good add to the Nerd2