Is an SPG necessary with a wireless computer?

[vladimir]

Another alternative would be to have a pony pressure gauge on your first stage. No hose but analog backup in case of emergency.

Yes, and so convenient to check, too: just doff your BC whenever you need to check your tank pressure.

 

[ROMO DIVER]

Considering I don't plan on ever having to use it and if I do it is just to give me ballpark of where I am it will work fine. Also, reading my pony guage is a good excercise for my buddy. Solo diving might be a little different, but probably not.

 

[Atom]

Another alternative would be to have a pony pressure gauge on your first stage. No hose but analog backup in case of emergency.

I don't think this really solves anything. If the transmitter fails you either...

-Call the dive and ascend: That means that whatever air you have is the air you have. If you were monitoring your gas that will be enough to get up (and with a wireless wrist unit there's really no excuse to not be aware of your gas at all times). If it's not enough you have bigger problems than transmitters failing.
-Continue the dive with a back-up SPG: That button SPG would be on the 1st stage, completely impractical for you to read. To me your buddy being able to read it and relay the number is a much more complex solution with no added benefits, you're not autonomous, and it requires a lot of maneuvering and communication for what should be a simple operation. A small SPG on a hose clipped you is a very streamlined backup solution, you'll be autonomous in your checks, you don't even have to signal your buddy that your transmitter failed and you can continue your dive as is.

 

[Colliam7]

I'm streamlining my kit, have just got a Vyper Air. I'm now thinking 'Can I lose the SGP hose?' I don't plan to dive much beyond 20m - How reliable are the transmitters?

The transmitter is for convenience; the SPG is necessity.

Well said!!! Short, sweet and to the point. My sentiments exactly (as a regular user of a Suunto computer and transmitter - which periodicially fails to sync, or loses data at lower pressures). 'Losing' the SPG hose doesn't add much to streamlining.

 

[hypertech]

If the SPG is a necessity, why is it that I've never had one and don't need it?

It's a useful tool, but it isn't a necessity. At least in my experience, with a proper predive check the wireless transmitter is sufficient.

 

[Dive-aholic]

If the SPG is a necessity, why is it that I've never had one and don't need it?

It's a useful tool, but it isn't a necessity. At least in my experience, with a proper predive check the wireless transmitter is sufficient.

It's been posted a few times that transmitters fail, even with a predive check. I've yet to see an SPG fail that way, though.

 

[DevonDiver]

One or the other.

A transmitter might die, but you're not actually losing air... so there's no real call for redundancy. Good situational awareness during the dive will mean you know what you air is when the transmitter dies... and can approximate the remaining air time to ensure a safe ascent. It's hardly a critical problem. On an extended 'away-from-home' dive trip, I would carry a 'spare' spg and hp hose in my dive bag though.

Of course, there is no harm in carrying both - but it can make a spaghetti mess out of your hose configuration (if you bother to configure your gear to be neat and streamlined). The port lay-out of your first stage will have a big impact on whether carrying both has drawbacks.

 

[Pedro Burrito]

If the SPG is a necessity, why is it that I've never had one and don't need it?

Some of us of advanced age remember when we didn't have SPGs at all. We might have known how much was in the tank when it was filled but had no idea how much we had once the dive started. I had this twitch in my left arm because I was always reaching back and pushing the J valve rod up to make sure that if my regulator started to breath hard then I still had a reserve because if that valve was down and the reg was hard to breathe then I was in trouble. I was looking at my first logs and all my dives were about 30 minutes, no matter the depth, because I never knew how much air I had left.

I dive with an air integrated computer and an SPG now.

 

[gypsyjim]

The transmitter is for convenience; the SPG is necessity.

Although in 1970 we did not yet know this. Sure made diving safer and more enjoyable when SPG's came into the picture, and suddenly we could actually monitor our gas supply during the dive!

Even when ( if?) I go to a transmitter, I would like a fail safe way to track my gas U/W.

 

[hypertech]

It's been posted a few times that transmitters fail, even with a predive check. I've yet to see an SPG fail that way, though.

SPGs fail too. They can stick, they can flood, some little piece of crud can get in the teeny tiny hole and stop them from reading. I guess you'd better get two just in case.

Every piece of equipment can fail. As long as you understand what can happen and what to do if it happens, there shouldn't be an emergency.