To use a back up SPG or not?

[Kilili]

I've used both together for years. I've seen enough computer malfunction to warrant doing so. I position it high on the chest, and angled towards me face. At times, when my hands are otherwise occupied, it's easier to read the spg than to try to read the dive computer on my wrist. Overkill? I think not. To each his own.

 

[melanie.]

I have personally seen an AI fail (don't know the guys computer model though).

So if you are prepared to call the dive if it stops working, by all mean skip the SPG. Even if it means you have only been down 10 minutes (what I saw happen).

If you don't want to call your dive, keep it on and out of the way. That way it is there if you need it

 

[davetowz]

If you decide to go AI only, which I would do, don't forget to include a hose in your save a dive kit if you also include an analog spg as the hose for your A/I( unless hose-less) will probably not support a normal gauge.

 

[PhuketPaul]

Hi,

I've been using AI for 5 years now, over 2000 dives and I've never had a problem or an issue; However


I use a Uwatec computer (Before a smart tec, now a Galileo Sol) and these pair with a transmitter permanently, unlike Suunto where you have to pair before each dive, I have seen many divers with Suunto AI forget to pair, or accidentally managed to pair with someone else's transmitter. You cannot pair again once you have entered the water!

I use an analogue SPG too, for 2 reasons

• Teaching - I like to be able to show students the same type of gauge as they will be using, so much easier with an SPG
• Pre dive check - I do 3 deep breaths of the reg before jumping in, to make sure the needle doesn't fluctuate (showing a problem with the airflow) and that no body has turned my air off whilst walking to the back of the boat (It has happened before with over helpfull boat staff, checking the air is on and actually turning it off) - The Computer doesn't respond quickly enough for the fluctuation check.

AS i mentioned I've never had a problem with the AI, but I have had a number of problems with the Analog SPG, SPG exploding, SPG over-reading by 60 bar (850psi), hoses or swivels leaking etc

Paul

 

[DevonDiver]

IMHO, you either trust the gauges you use, or you don't.

If you don't trust the AI, don't use it. Otherwise, there is no need for redundancy.

 

[Spimon]

I'm with DevonDiver - If you don't trust it to keep going, don't use it in the first place.

If either goes wrong, I'd be be heading up as soon as possible. Either can give up on a bad day.

 

[vladimir]

If I didn't have confidence in my AI, I wouldn't rely on it. I still might use it though, as a convenience. In that case, I'd have an SPG clipped to my hip D-ring. In fact, the latest incarnation of AI in my gear (Suunto D9) has proven to be very reliable, never dropping a signal (that I know of) in over 300 dives. Prior versions (UWatec Air-X, Nitrox-Z, US Divers Monitor II, Monitor III, or something like that) were, to varying degrees, less reliable, and I wore an SPG to take up the slack. I still bring an SPG on longer dive trips--I leave it at home for long weekends.

unlike Suunto where you have to pair before each dive, I have seen many divers with Suunto AI forget to pair, or accidentally managed to pair with someone else's transmitter. You cannot pair again once you have entered the water!

True, but to be clear, all pairing entails is pressurizing your regulator with the computer on and close by. Since my computer is on my wrist, I just have to be the person to open the tank valve--which is how I prefer it anyway.

 

[turnerjd]

I would say keep it, based on two points:-

1. fluctuation check - As PhuketPaul says, with an SPG you get a good fluctuation check when you try breathing before entering the water. Doesn't generally work with AI, or if it does, the time taken for the pressure to drop significantly is too long.

2. other guages - my SPG is part of a triple set. SPG, Depth, and compass. Keep SPG, keep all. If I lose the SPG I would have to add a compass and depth guage somewhere else.


Just remember, with AI only, if you lose the computer, you lose everything, no time or depth, or way of seeing your ascent rate etc.... . Personally I would like some backup.

Diving with a non AI computer, most people I know still use a triple guage and have a watch. This gives them a redundant depth guage and dive time. Going AI, why would you then throw away this redundancy by removing the guages? or with a non AI computer do you not have a depth guage and compass, only a single SPG?

Jon

 

[HowardE]

I have just received my new Mares Icon HD with AI and am considering keeping my SPG in case my wrist computer fails. Am I being over cautious or do most people use a wrist computer and a SPG? I will keep my SPG as a backup at least for the first few dives to make sure I know how it is functioning but once all clear do I keep or or put it to the side?

I have been using an AI computer for the last few years.

If I'm doing a simple single tank recreational dive within the no decompression limits, and I'm diving with a buddy. I may just go AI computer only, with no backup.

When I'm diving anything more than that, I always have a backup SPG. So more often than not... I have a backup SPG. However, I definitely prefer the ease of the AI computer's readout, and the more precise readings, and even estimated time remaining, especially when I'm working on SCUBA and maybe using a full face mask, I like the ease of not having to move around to find my spg. I know it's always on my wrist. When you're lying on the bottom in a prone position, unclipping an SPG takes more effort, and is more time consuming. But most recreational divers aren't doing that...

 

[endurodog]

I dive a Aeris T3 and have had no computer or connection issues. I keep a small SPG in my save a dive kit just in case.