Question Any objective data on SPG or transmitter failure rates?

[Belzelbub]

If I dove with a transmitter I would carry an extra battery for it and tool to change the battery. I would carry a hosed SPG in my dive bag.

Exactly. My SAD kit includes enough o-rings and batteries for two replacements for each transmitter. Plus 3 SPGs. Along with the necessary tools to change.

 

[Wants2divemore]

I appreciate everyone's comments. I've already decided what I personally use, the reasons behind that decision, and how I mitigate potential failure points. As a data guy, I was simply wondering if any actual objective data exists to use in my decision-making process. I always assumed that it didn't for the reasons I listed earlier. My own web search didn't turn up any data, but thought that if any data did exist, someone on SB would know about it.

I've had many people tell me their opinions about using SPG vs transmitter vs both, but their positions are based on theoretical concerns or anecdotes. One mentioned that GUEs position requiring an SPG was based on data, but I haven't been able to find said data.

@arkstorm Unfortunately, a poll on SB would be subject to selection bias and recall bias and not give me objective unbiased data. I'm sure it would be interesting, however.

 

[Tracy]

Is anyone aware of any studies showing failure rates of AI transmitters or SPGs? I've looked online and only found various anecdotal reports (including SB posts) but no actual hard data. I understand that it might be manufacturer dependent.

Please do not turn this into a "should you use an SPG for back up with a transmitter" thread. I know that has been debated extensively and understand the arguments on both sides.

Nothing truly objective, just personal experience. I probably have about the same number of dives with transmitters and gauges. Maybe 500 each way, give or take 100 either way.
Gauge failures due to breakage 3
Gauge failures where they weren't reading correctly 1
Gauge spool leaks, I have no idea, probably 20
Transmitter failures 1
Transmitter leaks 0

Personal experience, I have much better luck with transmitters. I have had both stop working on a dive, but I don't have spool leaks with transmitters since I don't use them with spools.

 

[Wibble]

Nothing truly objective, just personal experience. I probably have about the same number of dives with transmitters and gauges. Maybe 500 each way, give or take 100 either way.
Gauge failures due to breakage 3
Gauge failures where they weren't reading correctly 1
Gauge spool leaks, I have no idea, probably 20
Transmitter failures 1
Transmitter leaks 0

Personal experience, I have much better luck with transmitters. I have had both stop working on a dive, but I don't have spool leaks with transmitters since I don't use them with spools.

Ditto.

Never had a failure underwater.

Transmitters will not turn on when the batteries are flat, you catch that when checking your kit when loading on the boat. Must bring spare batteries with you as the CR14250 batteries are difficult to find except on the intarwebs.

Suunto transmitters are much harder to change the battery, requiring spanners and screwdrivers, than the Aqualung/Shearwater transmitters which just need a medium sized coin to undo the cover.

 

[LI-er]

From my own experiences with close to 700 dives:

Transmitter/receiver failure to communicate rates- over a dozen.

Backup mini spg gauge on extra thin miflex hose ziptied to BCD inflator (so it's like a half a hose): zero.

Dives missed or shortened due to failure of transmitter/receiver: zero

Convenience of wrist mounted AI computer: Not able to calculate but it's way up there.

 

[Belzelbub]

Suunto transmitters are much harder to change the battery, requiring spanners and screwdrivers, than the Aqualung/Shearwater transmitters which just need a medium sized coin to undo the cover.

Suunto also seems to think that changing the battery requires dealer service, which may be due to design. The screws holding the cover on thread into the plastic cover, so they recommend replacing the cover.

Also, for clarity, the current Shearwater (Swift) requires removal of 4 small hex head screws. They provide a tool, but you do have the 4 small screws to deal with. Definitely not as easy as the PPS style.

The PPS transmitters (Aqualung, Oceanic, Apeks, older Shearwater, etc.) are much simpler to replace the battery. An appropriately sized coin will work. The tool that comes with Shearwater Perdix is also a perfect fit for this cap. Tool lives in my SAD kit with the spare batteries and o-rings.

 

[Still Kicking]

OK here's some very unscientific "data":

Personal guesstimates working on rental gear/customer gear in busy shop ~10 years:

Transmitter failure to sync (hardware failures/software errors/crosstalk/dead batteries etc.): ~40

Irrepairable SPG failures (flood/inaccurate readings/internal leaks/broken face glass etc.): <10

SPG spool leaks (fixed): >300

Personal dives lost due to issues with analog SPGs during last 30 years: 0

I would guess systems worked on with analog SPGs outnumber those with transmitters at least 10:1.

 

[stuartv]

I'm team SPG. Inexpensive, they work without batteries and are simple to carry a spare with High Pressure Miflex hose on trips.

Just back from Bali and have seen every brand and style transmitter. While I think it's a "mature technology" they aren't cheap.

I believe now all except SUUNTO are the same broadcast protocol unless you have an older wireless computer that won't receive the newest transmitter's signal (SWIFT I think it's referred to?

Nope. Suunto and ScubaPro are both proprietary.

"Swift" is the name of Shearwater's transmitter. Their transmitter uses the same communication protocol as the PPS transmitters (i.e. they are all FCC ID MH8A), except that the Swift does not use a fixed transmission interval, like the PPS transmitters do. The Swift will vary its transmission interval in order to prevent collisions with transmissions from other nearby transmitters.

The Swift and all the PPS transmitters (branded variously as Oceanic, Aqualung, etc.) are interchangeable with regard to the computers they work with. Any dive computer that will work with any one of those will also work with any of the others.

 

[USdiver1]

Anecdotal evidence - in my 47 years of diving I have never seen a SPG fail while in use. I have seen, on a couple of occasions, a SPG get hooked on a dive boat seat and break when the diver stood up to go to the diving platform.

I have seen AI transmitters and computers both fail during dives [battery issues] as well as intermittent signal errors from the transmitter to the receiver.

In my experience, the value added of AI transmitters is in providing a more accurate remaining bottom time based on the user's air/gas consumption rate rather than just the programmed algorithms of depth/time. In a non-deco dive profile, it is more of a convenience than a necessity.

I personally use my AI equipped computer on 50% on my dives, going without AI on 50%.

 

[Belzelbub]

Nope. Suunto and ScubaPro are both proprietary.

As are Garmin and Ratio.

"Swift" is the name of Shearwater's transmitter. Their transmitter uses the same communication protocol as the PPS transmitters (i.e. they are all FCC ID MH8A), except that the Swift does not use a fixed transmission interval, like the PPS transmitters do. The Swift will vary its transmission interval in order to prevent collisions with transmissions from other nearby transmitters.

Slight clarification / nit-pick.

The FCC ID for the Swift is not MH8A. It's actually 2AO24-17001. FCC ID 2AO24-17001

The Swift does use the same transmission frequency and information coding, so the transmitters and computers are compatible.