Feature request for rebreather HUD

[tbone1004]

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...

I use a "dilout" concept where my bailout and dil are in the same bottle. The onboard 3l is a suit/wing inflation bottle. Planning is not based on "thirds" since that is pretty useless depending on the cave profile. You plan it based on time and distance to get out. Planning is quite a bit more complicated for cave diving since you must know your kick speed and SAC rate in order to plan. Once you're in the water, you basically have to hope that the numbers were right.
I have button gauges on my O2 and inflation bottle, but prior to switching to dilout in the rack, the onboard 3l was button gauged. You check it at the beginning of the dive, and go. If you run out, well that's what offboard plugins are for, but a 3l lasts a LONG time.

On whether the light would be useful or not. It is exceptionally rare that I actually look at my buddy, even in the ocean. I'm either behind of, or in front of them. If I'm behind them, I certainly can't see their face, and if I'm in front of them, I'm not going to stop and turn, or duck between my legs to look to see a light.
To me it's one of those things that certainly doesn't hurt anything and may be useful for instructors during mod1, but it's not something that I would get any use out of. I say this having a buddy with a Liberty who's buddy light is gargantuan and wicked bright on top of the canister, and barely ever noticing it while diving with him. Again, I'm not opposed to them, but I think there are better things worth investing the R&D cost in. I.e. @Shearwater completely eliminating fischer cables which still exist for literally no reason, and getting a subconn bulkhead so we can use our CCR computers while diving open circuit without a pigtail, or putting WAI in the petrel for the same reason.... hint hint wink wink

 

[JohnnyC]

Poseidon and Ouroboros both have buddy lights on the back of the unit as well. One on the HUD does nothing unless you're in sight of it. So if the point is to be able to recognize an unsafe loop condition that your buddy is unaware of, only making it available for one orientation is limiting. Now I've only been diving with a few JJ guys, but I have yet to see a buddy light on any of them, HUD or otherwise. It's entirely possible that their HUD's are different than yours. I'm not down with all of the JJ revisions over the years. DiveCAN vs others maybe? Or is it because it's only on in an emergency? I would never know. Anyway, rarely are we facing each other, so if seeing their HUD area is the only way to see an indication, it's only worthwhile in a few limited scenarios.

It needs to have some sort of "I'm working" indicator. If there's nothing, you don't know if it's working or not. If it only goes off if it alarms, you're never sure if it's working until you reach that alarm state, in which case, what's the point? Let's say it fails, your buddy is breathing an unsafe loop and you are none the wiser. The thing with the PO2 display on the HUD, you always have confirmation that it is functioning. It is ALWAYS giving data. A buddy light that doesn't give you confirmation is like the thermostat in the liquid O2 tank on the Apollo 13. When it fused shut and the tank got to over 1000 degrees, the temperature still said 25. Because that's as far as the readout went. Turns out 25 is where it was supposed to shut off. If the alarm state is the only way to know it's functioning, you'll never know if it's working until it's an emergency. Why should a HUD display anything then unless it's dangerous way above or way below setpoint? HUD's exist solely because they give us constant data. If they didn't, there would be no point. If you want your buddy to know the state of your loop, they need some sort of data. In this case, the absence of data isn't data enough in my mind. And it is a positive indicator of failure. You want something to tell you when something isn't working, you don't want to just find out when it doesn't do what it's supposed to do. Hell, even cells tell you this theoretically, mV either dirt dives or skyrockets. Not always, but often enough.

The Meg 2.7 handset (the APECS controller, not the Predator) actually has a little spinning cursor so that you know the unit is actually working. Otherwise you look at it and it will say your setpoint is whatever all day long. Apparently it was determined that the risk of frozen electronics was enough to include it.

As for the handset alarming, I'm not talking about blanking out the screen so that it's useless. I'm talking about making the alarm condition effing obnoxious until you deal with it. A giant square of flashing red is much more apparent than a single red LED blinking, or just the PO2 row. And there's nothing that says it has to stay this way, only that it will until you do SOMETHING. Whether that's switching to bailout on the computer, driving the PO2 below 1.6, whatever. An impaired diver might not immediately react to minimal red flashing, but something big and apparent trips that lizard brain like no other. Right now the PO2 readings just flash red. If you look at the video, you can see that it's only the PO2 row of his controller that's flashing red for danger. I guarantee his HUD was as well. He's lucky his buddy was attentive. If the whole screen was flashing red, it would be much more apparent to everybody. I certainly notice being able to see my buddies Shearwaters much more often than you would imagine. And you don't have to be able to interpret the data the computer is displaying, you just have to recognize it's in angry mode. Actual bright flashy things get your attention, even if you don't have direct viewing angle to it. Aside from the fact that you'd really have to be pretty dark to see the LED (the Meg HUD's are rough even with it pointing straight at you on the other side of your mask), and you'd never see it if you've got your light illuminating your buddy at all, ultimately it needs to be unobtrusive enough that it's not a distraction, heck, even if it takes you a second to look for it, but actually gets your attention when it needs to. "No way to tell if it's working" is a bit too unobtrusive. The Hammerhead "buddy light" is too obtrusive.....


It's not that I disagree that putting a little LED on the NERD is a bad idea, I just think that it's ineffective the way you describe it, so what's the point? If you're going to use some system to alert your buddy, don't half @$$ it, whole @$$ that thing so there's no way your buddy can miss it. Make it like a damn xenon strobe. Make it a Cree XHP 70. Make the sucker impossible to ignore. Do the DIVA thing and vibrate the hell out of the mouth piece with a motor loud enough that your buddies can hear it.

Aside from the difficulty in implementing the architecture, wireless buddy state is probably the best way to ultimately go about it. If your buddy is alert, they're definitely gonna notice their computer saying something is wrong. And if it's the, "your buddy is gonna die" alert, they're gonna notice it right away.

 

[doctormike]

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

Yup! And I guess in cave diving, that might be a situation where the HUD buddy light might be a problem, since you probably aren't spending a lot of time face to face, right? More common to be in a line, correct? So maybe Johnny's idea of a light somewhere else on the unit would be helpful in a cave. Of course, that's more wiring, as opposed to just putting it on the HUD that's already there...

 

[doctormike]

It needs to have some sort of "I'm working" indicator. If there's nothing, you don't know if it's working or not. If it only goes off if it alarms, you're never sure if it's working until you reach that alarm state, in which case, what's the point? Let's say it fails, your buddy is breathing an unsafe loop and you are none the wiser. The thing with the PO2 display on the HUD, you always have confirmation that it is functioning. It is ALWAYS giving data. A buddy light that doesn't give you confirmation is like the thermostat in the liquid O2 tank on the Apollo 13. When it fused shut and the tank got to over 1000 degrees, the temperature still said 25. Because that's as far as the readout went.

All good points, and thanks for the informative post! But the implementation of something like this does include design decisions and tradeoffs, and I still don't think that the absence of a "working" status for this particular thing (HUD buddy light) makes it worthless. I mean, it would be easy enough to just have the buddy light have two states, red and green, but then people might complain about it always being on and distracting or something.

Think about audible alerts on dive computers. Now most of us don't like them, but that doesn't change the fact that many equipment designers and end users consider them desirable features. So we don't have the audible alarms constantly emitting one sound to imply "working but no alarm" and another to indicate an alarm state. The fact that it only goes off when there is an alarm doesn't make it meaningless.

Unlike the Apollo 13 thermostat, the buddy light is not the primary way of communicating vital information to the operator. I think that it's acceptable to only have it alert when the PO2 is out of range. Yes, this doesn't take into account your three failure scenario (PO2 out of range, impaired diver who doesn't respond to their primary data system, and failure of the buddy light). But I don't think that it's worthless just because it would fail in that specific scenario.

And even a big screaming alert sometimes fails if the operator isn't attentive, like the diver who died on a training dive in Hawaii with the O2 off, despite being on a Liberty with the vibrating handset. A buddy light just lets you include one auxiliary backup brain into the system which might break the accident chain.

 

[tbone1004]

@doctormike the issue I see with it, and I think it's the same as @JohnnyC is that even in open water, you don't see your buddy face to face hardly ever aside for descent and deco. Arguably these are the two times were things may have a higher probability of going sideways, but during the dive, there is no way to notify the buddy that something is wrong. Sure it confirms that something is wrong when you look, but it doesn't inform the buddy that you need help. Again, I'm not opposed to having it, but I don't see the merit in going out and designing it either.

For you as a CCR photographer, also remember that a forward facing HUD light is going to reflect against the camera...

 

[njdiverjoe]

The Meg 2.7 handset (the APECS controller, not the Predator) actually has a little spinning cursor so that you know the unit is actually working. Otherwise you look at it and it will say your setpoint is whatever all day long. Apparently it was determined that the risk of frozen electronics was enough to include it.

The APECS4 also has the spinning cursor. Some of the megs (I think the CE version?) have two indicator leds on the HUD, one for self and another for buddy. As long as the water isn't too bright -- I've got no problem looking over and checking another meg diver's p02 by looking at their HUD for a few seconds. Admittedly, if you didn't know what to look for it might not be very noticable ...

The APECS4 handset screen also flashes black-white-black-white when there is an alarm, which I think it very noticable. I actually had an "incident" where my handset was showing over an hour of extra deco more than I actually had accumulated, as I blew through stops the handset alarms kept going off. Back on the boat the two other divers I was down with both commented that the handset flashing was extremely easy to notice.

 

[JohnnyC]

I think the big difference between a small "function" LED like green for good, and an audible alarm is that auditory alarms quite significantly fall into that "obtrusive" category I mentioned. A green LED is much less so. I have to look at you to see the LED. I can't get away from some dude's beeping Suunto..... And it's certainly not obtrusive to the diver using the unit since they've already got other LED's straight in their eyeballs. Hell, look at the AV1 HUD, it's like a Jensen car stereo. I'm surprised that it doesn't play the Soviet national anthem during calibration. Although if it did I'd buy one just out of admiration for the brass ones the dude has.

As to your disagreement of my HUD comparison, the HUD communicates vital information to the operator. Absolutely I wholeheartedly agree. The buddy light communicates vital information to the other "operator," your buddy. If your contention is that your buddy needs to be informed of your loop viability, needs to be essentially the backup operator in the event the primary is unable to, then he needs to be informed whenever he decides he decides he needs that information. If you're going to put the onus on your buddy to be attentive to your loop viability, you need to make sure they have the tools to do so. If you're (the royal you're) going to complain about one small LED on a HUD full of other LED's, I would think you were being obtuse simply out of spite.

Ultimately I just don't think the juice is worth the squeeze unless you're gonna fill the whole glass. It's very true that no matter the number of alarms, there will still be people who splash with their O2 off while holding a camera without running a checklist or doing a pre-breathe or <insert any number of stupid things here>, but if you're going to design a safety system, you should design one that provides the most benefit with the fewest drawbacks, not a piecemeal solution that has very limited utility in very limited situations. It's not "the proof is in the pudding," it's "the proof of the pudding is in the eating."

Maybe the best compromise is a small green LED that says, "i'm ok," but flashes super bright white like the DIVA one during an emergency, no colors, no patters, just obnoxiously bright strobing. Ideally put one on the head too so that you're really drawing attention to yourself from any direction, and flash the handset since apparently it's noticeable as well.

 

[Caveeagle]

Yup! And I guess in cave diving, that might be a situation where the HUD buddy light might be a problem, since you probably aren't spending a lot of time face to face, right? More common to be in a line, correct? So maybe Johnny's idea of a light somewhere else on the unit would be helpful in a cave. Of course, that's more wiring, as opposed to just putting it on the HUD that's already there...

I still think it’s a good idea. I was just saying it’s not a primary indication of a problem. Solid communication and team awareness is what I hope is my first indicator my buddy is ok. Once I notice a problem, and am swimming towards said buddy, A red buddy light might give me a second or two warning of what is wrong. It might not be easy to see what the wrist controller is reporting, but in an emergency, it’s all about getting safe breathing gas to the diver.

When in doubt, bail out... right?

 

[doctormike]

Sure it confirms that something is wrong when you look, but it doesn't inform the buddy that you need help.

It informs your buddy that your computer is giving you an alert. They should be able to tell if you are normally responsive, and if so, you can probably deal with the alert yourself. The target failure mode is for a diver becoming impaired without losing the loop, or a diver who is inattentive and not realizing that the unit is in alert status (like the diver who died during training in Hawaii). Like I said, it just lets you include one more brain in the system and possibly break the accident chain. It can't deal with every possible scenario, but that doesn't mean that it's not useful.

For you as a CCR photographer, also remember that a forward facing HUD light is going to reflect against the camera...

It's just a tiny LED, how would that affect the images? And assuming that it works like the current buddy lights that are available now (only on when there is an alert) I would probably be more concerned about my buddy fixing his high PO2 than the effect of the buddy light on my photo!

 

[doctormike]

I think the big difference between a small "function" LED like green for good, and an audible alarm is that auditory alarms quite significantly fall into that "obtrusive" category I mentioned.

Of course, an audible alarm is much more obtrusive if it's constantly broadcasting that it's working, so it's not a great analogy. But the point is that we don't say that audible alarms are worthless just because they don't constantly announce their functional status. People shopping for dive computers want them and buy them.

For another example, I'm not a pilot but I know that some planes have audible and tactile stall alarms that say "pull up" or whatever in a recorded voice. But that same system doesn't constantly announce that it's working OK.

As to your disagreement of my HUD comparison, the HUD communicates vital information to the operator. Absolutely I wholeheartedly agree. The buddy light communicates vital information to the other "operator," your buddy. If your contention is that your buddy needs to be informed of your loop viability, needs to be essentially the backup operator in the event the primary is unable to, then he needs to be informed whenever he decides he decides he needs that information. If you're going to put the onus on your buddy to be attentive to your loop viability, you need to make sure they have the tools to do so.

But he does have those tools. His tools are his situational awareness, his ability to communicate with another diver, and his ability to read the primary display on a controller. The buddy light only needs to transmit one bit of information - alert or no alert. If you are diving with someone and you see that alert, you give an OK sign and look for a response that indicates an engaged diver. You watch to see if he does a dil flush or hits the O2 MAV or do whatever it takes to deal with the alert. And THEN, if you don't get a good response, you can check his controller and go from there.

The buddy light doesn't need to tell your buddy exactly what the problem is, any more than an audible fire alarm needs to tell building residents where the fire is. it just needs to wake people up and get them to either evacuate or get further instructions.

Ultimately I just don't think the juice is worth the squeeze unless you're gonna fill the whole glass. It's very true that no matter the number of alarms, there will still be people who splash with their O2 off while holding a camera without running a checklist or doing a pre-breathe or <insert any number of stupid things here>, but if you're going to design a safety system, you should design one that provides the most benefit with the fewest drawbacks, not a piecemeal solution that has very limited utility in very limited situations.

But that's the sort of pushback that could apply to any safety innovation. It's sort of what I heard about my checklist sticker. We are talking about a very simple, unobtrusive and cheap thing that could address one failure mode. The fact that it doesn't address everything doesn't mean that it does nothing. Maybe if the deckhand on Brian Bugge's boat had noticed the buddy light alarming, they wouldn't have let him splash. You know, breaking the accident chain. As you of course know, CCR divers can become impaired in ways that OC divers usually don't, so I think that it's worth considering.

Maybe the best compromise is a small green LED that says, "i'm ok," but flashes super bright white like the DIVA one during an emergency, no colors, no patters, just obnoxiously bright strobing. Ideally put one on the head too so that you're really drawing attention to yourself from any direction, and flash the handset since apparently it's noticeable as well.

Good though! Maybe someone from Shearwater will add that to their design notes as a public comment.