Shearwater coming out with new DC?

[guyharrisonphoto]

Oh, well . . . . One more try.

My photo rig is pretty neutral, as "any documenter" strives for. This does not change the extra difficulty of handling it one handed in a current where it is being pulled horizontally which is a different animal.

In fact, most photogs with big rigs do carry the rig in both hands in front of them through most of the dive. More streamlined and stable and instantly ready for the shot. Of course, you can always drop the rig (mine is clipped off on a flexible safety cord) in an emergency if you just have to reach some piece of gear, but you really don't want to drop or shift it around unnecessarily for routine things like looking at an SPG. Much better, more efficient, to just have the gas info right there on your wrist. Doesn't need to be on the camera screen, but since we are fantasizing . . . that would be great!

Also, no issue with reading gauges, since with AI, all of your gauges are right there on your wrist so there is only one place to look.

Let me offer an example from my real-world diving. When shooting goliath grouper aggregation or sharks off of Jupiter, Florida, the fish are on wrecks and ledges at 90 to 135 feet deep, on the edge of the gulf stream, almost always in very strong currents. This is the exact situation where I would be monitoring my gas most often. It is also the last situation where I want to shift the camera to one hand and go through multiple routines of unclipping, lifting and reclipping my SPG,at depth, being pulled by the current, and surrounded by big fish action. Sometimes, even, I have to try and shoot with one hand on my camera and one holding on to the wreck or bottom. AI is just a better and safer option here. Triple that if it is a night dive where you would also need to bring a light to bear on the SPG.

You might feel you don't need it for your underwater demo work, but I have a real circumstance where it is better and safer than an SPG. Lots of different divers out there. I can imagine that many kelp divers would also appreciate not having to fiddle with unclipping, lifting, and clipping gauges when in the kelp forest--just a guess.

As for "hampering" use of the hands, I don't get that. On non-photo rec dives my hands are folded in front of me. My "use" of the hands is precisely for photography (or hunting, or scootering). I don't think you are really saying that divers should not photograph, hunt, scooter or do things with their hands just because the "best" thing is to unclip and re-clip an SPG. AI is at its most useful when your hands are occupied and this is a very valuable option for rec divers.

Whether Shearwater wants to do it is a different matter, for them to decide under their business model. They have a ready and waiting customer if they do, and I think I am not the only one.

 

[dmaziuk]

I think the Liquivision computers/transmitters use ultrasonics. I think Oceanic and others use RF.

Although you technically can use electromagnetic waves underwater, in practice it requires mile-long antennae. Or did last I looked. So I'm not sure what sort of RF they'd be using.

 

[scubadada]

Since Shearwater is watching this thread, I will add my perspective as a recreational diving photographer. I use a "two handed" DSLR photo rig. I also dive a hogarthian long hose rig with a clipped off spg, along with my AI computer (Galileo Sol). Having gas info on my wrist is invaluable, as compared to holding my heavy camera rig in one hand, unclipping the spg, checking it, and re-clipping it. That sounds like no big deal but before I hear "equipment solution to a skill problem", try it at 130' in a strong current dealing with the photo rig! In fact, I view AI as a valuable safety factor in that regard, and more than just a convenience. It is a real, tangible, valuable benefit that I desire and why I have not taken the step of buying a Shearwater yet.

As for your other questions, I dont (and don't know anyone and I dive with an advanced crowd including some tech divers) who uses "rock bottom" for rec diving. That being said, my computer allows me to set a "surface reserve" which is the amount of gas that will be in my tank when I reach the surface. It also has a predictive gas usage algorithm, which will tell me to begin my ascent at the pressure which will assure I arrive at the surface with the set reserve, including my predicted gas consumption through the ascent and safety stop. I have found this to be very accurate at least the way Scubapro has implemented it. Thus, my "surface reserve" is the amount of gas available for my buddy if needed during an ascent at the end of a dive. While not as formal as "rock bottom" I can set the reserve at whatever I want, so if I want a cushion, I can set it at 1000, say, on a deep dive. Of course, I will get sent up early by doing this. For dives up to 90' I leave it set for 600, which is enough to get a buddy to the surface in a true emergency OOG situation (which will be faster that usual and not include the safety stop).

If you do "rock bottom" you can set the computer to give a warning at your calculated surfacing pressure or any other turn pressure you want.

As for real time SAC, my remaining gas time is all calculated in real time based on change in tank pressure over time. So, it is, effectively, "real time" SAC calculation during the dive, but translated and displayed as useful information regarding remaining dive time. If you are working hard, the computer automatically takes this into account in its prediction. No mental calculation necessary during the dive.

Such a feature would be essential on any computer I get. I was going to look at the Liquvision Omnix, but posters here have indicated it does not have this feature. That makes it a no-go for me.

My computer also offers buddy air monitoring. My buddy and I can program our computers to read each other's transmitters. A button push during the dive brings up your buddy's gas supply. However, I don't use this much as we usually do a mutual gas check 2 or three times during the dive. Also, because my computer (like most) uses rf transmission, you have to be within 4 or 5 feet of your buddy's transmitter to get the reading from them. So, it is a handy feature, but not necessary.

However, Liquivision uses ultrasonic transmission, which they say is good over pretty long distances, and offers an option to display buddy gas on the main dive screen. This would greatly increase the utility of this feature if it is effective, but I would not trade buddy air monitoring for an effective predictive gas use algorithm.

So, that is my take on why AI is a desirable feature for both basic and advanced rec divers. Hopefully, it offers tech divers some insight into why this feature is so popular and so useful to their rec compadres.

Nice post Guy, we, AI folks, take quite a beating here on SB. I would imagine most have never used AI, but are philosophically opposed

 

[dmaziuk]

How would others use AI? Rockbottom monitoring for a buddy pair, realtime SAC rate info, a reminder to switch on sidemount or independent doubles?

All of the above. Mostly it's about convenience of having everything on your wrist. (HUD would be even nicer if done right.)

I believe comms is ultrasound and it's most likely periodic pings rather than continuous noise. Keep in mind that ultrasound doesn't travel too far in water so the noise is fairly localized, this also limits the range for buddy monitoring. (On the plus side you don't have to care too much about cross-talk.) Overall I can see how a vendor wouldn't want to get into this can of worms unless they already have a line of WAI computers.

 

[scubadada]

Crap. Absolute crap.

I dive in caves. I dig open underwater caves. This may involve setting underwater charges, setting up scaffolding, moving boulders, drilling, hammer and chiselling, you name it, we do it.

We don't need AI.

As for your "heavy camera rig". Jill Heinarth doesn't use AI. This is because she's made her rig close to neutral, like any real underwater documenter does.

Sent from my iPhone using Tapatalk

You seem somewhat inflexible in your thinking. You don't need AI, we want AI, for our own reasons. You don't really have less than 500 dives but are so sure of yourself, right?

---------- Post added January 8th, 2016 at 02:54 PM ----------

I don't get the need to "glance at my wrist", I just glance down at the gauge clipped to my left chest ring.... look ma, no hands!

FWIW - I don't "need" it, I am unsure if I "want" it, but those that do, have at it.

Its a big ocean, plenty of room to share.

Enjoy your dives!

That's where my backup SPG is, all I do is glance down

 

[Lorenzoid]

. . .
As for "hampering" use of the hands, I don't get that. On non-photo rec dives my hands are folded in front of me. My "use" of the hands is precisely for photography (or hunting, or scootering). I don't think you are really saying that divers should not photograph, hunt, scooter or do things with their hands just because the "best" thing is to unclip and re-clip an SPG. AI is at its most useful when your hands are occupied and this is a very valuable option for rec divers. . . .

I think what I am hypothesizing is that "big rig" photography, hunting and scootering might be beyond the realm of "rec diving." (Yes, I realize my definition is not the common one.) Maybe those kinds of divers would be best served by something entirely different than what we think of today as AI. I fantasized about a camera display linked to the computer. Someone else mentioned a heads-up display.

 

[scubadada]

SB has really changed over the last several years, many more dogmatic posters with questionable experience and expertise.

 

[lowviz]

...//... Keep in mind that ultrasound doesn't travel too far in water ...//...

You are going to upset a lot of sea critters with that statement.

Electromagnetic waves will propagate through short distances, too, if you pick your wavelength carefully:

dx.doi.org/10.4236/jemaa.2011.37042

”It should be also pointed out, that practical compact antenna designs can be developed in the optimum frequency range of 3 - 100 MHz for underwater devices due to the large permittivity of water (εr = 81). For example, a half-wavelength loop antenna operating at 100 MHz inside fresh water has a diameter of only 5.3 cm. Therefore, the optimum frequency range can be used in practical underwater communication systems and it will provide minimum losses for shallow propagation depths.”

I know what you are thinking about, ELF communications for submarines. Yeah, HUGE antennas. But then subs tend to stray farther than most dive buds...

 

[guyharrisonphoto]

Hi Lorenzoid, I think you are right that diving with a big camera rig poses special challenges (and requires a special and knowledgeable buddy). I do take this into account when I dive. Still, given the photog's hand position (in front, holding the camera tray handle, in the line of direct vision) the wrist location for AI could hardly be improved. Yes, a camera screen display would be nice, but that tech is far in the future and, really, not needed. Current tech would be fine.

 

[dmaziuk]

You are going to upset a lot of sea critters with that statement.

...as opposed to low-frequency sounds. I believe the rule is propagation proportional to wavelength is what I meant.

Electromagnetic waves will propagate through short distances, too, if you pick your wavelength carefully:
...
For example, a half-wavelength loop antenna operating at 100 MHz inside fresh water has a diameter of only 5.3 cm.

...

exactly. According to shearwater petrel 2 is 8.3x7.4x3.9 cm so it'd have to be pretty much petrel-sized in 2 dimensions to house the antenna. Not sure that's a plus.