Question Redundancies

[johndiver999]

I'd actually say you're "under" thinking it in this particular scenario, as there are various options. In many places, you can see the surface, so judging safety stop depth isn't difficult. If vis is bad enough that you cannot see the surface, then you can deploy a DSMB -- your buoyancy will thank you for the visual reference and you can put a knot at 15 ft for depth info. There's also the near-certain probability that your buddy's depth gauge still works.

yes and the fact that the op mentioned difficulty with a safety stop shows his unfamiliarity with the issue. Rather than a safety stop depth, a more critical issue is how to perform an ascent at the correct speed (without a computer).

In the event of a computer failure (during a deep recreational dive) one might want to be able to deploy an smb from depth and then slowly wind themselves back up to the surface.

An smb on a reel or spool, provides a considerable degree of safety and can be very helpful in several "problem" situations.

When it comes to redundancy, the diver needs to carefully think about what kind of issues they will be able to handle (and which ones they won't - also ones they deem so unlikely that they are not worth worrying about).

The point is that this is a personal decision and the diver should be able to clearly justify their decisions (at least to themselves). Every single piece of redundant gear comes at a cost of added complexity and also an increase in the probability of a gear failure. It is not "maintain your gear and bring whatever you feel like".

 

[OTF]

A DSMB+spool with a knot in the line at 15 ft can mark your safety stop depth as a backup, and help you stabilize there by giving a visual reference or physical thing to hold.

A DSMB + spool is a really great thing to have, a simple tool useful for probably a dozen other totally different scenarios from rescues to navigation. But new divers need to train and practice to use them properly. It's a simple thing but screwing it up can drag you to the surface.

 

[Eric Sedletzky]

What happened to "Follow your smallest bubbles"?
That is the very most basic stuff.
Do they not teach that anymore?
And if you're within your NDL (this is a basic forum) a 15' stop is not mandatory.

 

[Zef]

A DSMB+spool with a knot in the line at 15 ft can mark your safety stop depth as a backup, and help you stabilize there by giving a visual reference or physical thing to hold.

A DSMB + spool is a really great thing to have, a simple tool useful for probably a dozen other totally different scenarios from rescues to navigation. But ALL divers need to train and practice to use them properly. It's a simple thing but screwing it up can drag you to the surface.

Fixed that for ya!

-Z

 

[Belzelbub]

On a dive not too long ago out of the four of us... three of our computers went caput.

Three out of four computers died on a dive? Where were you diving? Chernobyl?

I’d say that failure rate is highly unusual.
I carry two dive computers, one is AI, one is not. I use a transmitter, and always bring a spare SPG or three. They stay in a bag on the boat.

I use PPS transmitters. They are quite simple and quite reliable. I’ve had one fail on initial startup. I bought it used, and Oceanic replaced it for a service fee. Failure was instantly recognizable as NO COMMS on the computer screen. Other manufacturers use more complex transmitters, and in some cases, those seem less reliable.

I’ve also had an SPG fail. This happened during a dive. Failure mode was that needle stuck at a previous pressure. I only noticed as I was quite familiar with my air consumption and the reading did not align with what I was expecting. For a more novice diver, this could have easily been missed for a while.

So for me, I’ll continue to dive with my transmitter, and my Octo Z combo inflator. Works for me. The buddies I dive with, either dive a similar setup, or are familiar with how my gear is setup.

 

[went_postal]

Wow... a lot of bold assumptions and reading between lines that don't exist.

per

the fact that the op mentioned difficulty with a safety stop shows his unfamiliarity with the issue.

I believe my comment was more about another new diver I was with had trouble with safety stops and buoyancy. And that ties into the other comment from someone about "the entire dive was a safety stop."

yeah... I get it. In rec diving safety stops are not needed... That doesn't mean that when you are out refreshing your skills/practicing that you shouldn't practice the stops. Needed? No. Good to practice? I think so.

I get it that others with 100s of dives get to a point where they feel it's a bit of a throwaway. I don't happen to be at that point. And it's not that I don't understand anything or that I am unfamiliar with anything. My choosing to do/practice safety stops is a personal choice at my present stage of my scuba journey.

A DSMB+spool with a knot in the line at 15 ft can mark your safety stop depth as a backup, and help you stabilize there by giving a visual reference or physical thing to hold.

A DSMB + spool is a really great thing to have,

The knot at 15ft sounds like a great idea and not something I had heard referenced before this thread. There have been a couple of people that pointed that out.

I do have a DSMB and I have/do practice how to use it.

What happened to "Follow your smallest bubbles"?
That is the very most basic stuff.
Do they not teach that anymore?
And if you're within your NDL (this is a basic forum) a 15' stop is not mandatory.

Yes... not going up faster than your bubbles is still absolutely a thing. At least it was with my instructor. And we did CESA. All sorts of fun stuff like that.

One of my issues was depth perception (of which mine is not awesome) and knowing your distance from the top... the DSMB 15' knot sounds like a great workaround in case of an issue.

Three out of four computers died on a dive? Where were you diving? Chernobyl?

two Cressis that seem to be temperamental and only want to tell you anything if/after they get wet. They got wet... batteries must have been toast. Not mine... they were loaners.

The other was my Apple Watch where the Oceanic+ app decided to wet the bed. Apparently the issue I encountered is a very common issue that Oceanic has yet to really fix. Apple wants to point at Oceanic and Oceanic wants to point at Apple. I just wanted it to work.

Funny enough... as the crow flies we were not that far from the nuclear reactor.


Sort of the whole reason I started this thread... pretty much came to be the other day while testing/setting up my new gear. I was in a pool getting everywhere where I wanted it and trying out all the new kit. At least three times my scubapro G3 lost access to the transmitter. All the stuff is new and this was the first time any of it had been in the water. This was pretty much the spirit of the thread and my initial question.

The dive computer was working... the Air Integration... MOSTLY. Would I need to stop a dive because the transmitter decided to take a lunch? I wouldn't think so... I had my console with the SPG and depth gauge on it (depth and everything else on the computer was working).

So... that was really what the initial question was about... Knowing that it is a possibility/can happen would you really dive without a gauge telling you how much air was in your tank? My current answer is no... and it was a fairly moot point because I had already ordered the gear. I just thought it interesting that the SPG was not considered "mandatory" by some.

 

[Belzelbub]

So... that was really what the initial question was about... Knowing that it is a possibility/can happen would you really dive without a gauge telling you how much air was in your tank? My current answer is no... and it was a fairly moot point because I had already ordered the gear. I just thought it interesting that the SPG was not considered "mandatory" by some.

For me, an SPG is not mandatory. I bring spare SPGs on the boat, but they stay in a bag. Haven’t actually gotten them wet in a while. Yes, a transmitter can fail, but so can SPGs. Mechanical devices and electronic devices both have failure rates. Redundant SPGs haven’t really been a thing, so why should a backup be required for a transmitter. Electronics tend to fail most on startup (apart from depleted batteries, i.e User Error), and often fail spectacularly, so there is no question that a failure has occurred. SPGs tend to fail in more subtle ways. I much prefer an easily recognizable failure to one that can escape detection.

Like I said, I’ve seen both fail, but only the SPG failed on the dive, so I’m suspicious of them.

And not all transmitters are created equal. I prefer the simplicity of the PPS version (Oceanic, Aqualung, Shearwater, Sherwood…) to some of the others. They turn on when pressure is detected, and turn off when it drops below 50psi. Other brands require pairing, selecting channels, go into sleep mode if not enough pressure change is detected. All of that adds complexity, and for what gain?

But, having had that many failures on one dive, I can absolutely understand why you’d want to add redundancy. I certainly would lose faith, at least in those brands that failed.

 

[Eric Sedletzky]

If SPG's were so unreliable then tech divers doing 300 + ft dives would have sworn them off years ago, but they haven't. But if they were given a choice of using a transmitter/computer or a simple glass and brass SPG for tank pressure, my guess is that they will pick the SPG.
Hey, why don't we find out?

 

[bradlw]

At least three times my scubapro G3 lost access to the transmitter. All the stuff is new and this was the first time any of it had been in the water. This was pretty much the spirit of the thread and my initial question.

The dive computer was working... the Air Integration... MOSTLY. Would I need to stop a dive because the transmitter decided to take a lunch?

On our recent keys trip, I was chatting with the captain.... something about computers and probably started by a discussion about how their rental gear sets did not include a computer...which I found refreshing given the depths and conditions there...
Anyway, He said with confidence that one failure that has ended more dive trips than anything else in his experience was air-integrated computers

 

[Allen-1]

Wow... a lot of bold assumptions and reading between lines that don't exist.

Well, yes - this IS an internet forum...

The knot at 15ft sounds like a great idea and not something I had heard referenced before this thread. There have been a couple of people that pointed that out.

I have yellow nylon cord tied at 20' and at 30'. The 30' gives me a warning that the 20's coming up, and the 20' allows me to have it within sight at 15' safety stop. I chose 20' rather than 15' because the line's unlikely to be absolutely vertical unless I'm in dead calm water.

Sort of the whole reason I started this thread... pretty much came to be the other day while testing/setting up my new gear. I was in a pool getting everywhere where I wanted it and trying out all the new kit. At least three times my scubapro G3 lost access to the transmitter. All the stuff is new and this was the first time any of it had been in the water. This was pretty much the spirit of the thread and my initial question.

The dive computer was working... the Air Integration... MOSTLY. Would I need to stop a dive because the transmitter decided to take a lunch? I wouldn't think so... I had my console with the SPG and depth gauge on it (depth and everything else on the computer was working).

So... that was really what the initial question was about... Knowing that it is a possibility/can happen would you really dive without a gauge telling you how much air was in your tank? My current answer is no... and it was a fairly moot point because I had already ordered the gear. I just thought it interesting that the SPG was not considered "mandatory" by some.

I have air integration, backed up with a SPG. If I were to lose both, I'd call the dive.