I’ve read it all and still need opinions on computers

[tursiops]

His response was “ you sure can but I strongly suggest you have a backup SPG as I have seen more than a few transmitters fail and divers not knowing how much air they have”. I thought the big draw to ai was the elimination of a hose and being able to be more streamlined. His response is making me rethink the importance of ai.

I would.not put too much faith in this info. It was probably something he heard, read, or learned some years ago, and has not upgraded it. the point of AI is primarily to put your pressure on your wrist, which is usually easy to see. Removing a hose or not is secondary, and depends on your risk management. I, and others, do NOT carry an extra SPG except in our dive bag.

A number of us here cave and wreck dive with just transmitters, but we’re using Shearwater Perdix or Teric computers. I do it myself. That should give you an idea of the reliability of some AI, anyway.

The old "not reliable" info is heavily skewed by many of the early transmitters being from Suunto, and they were, well, not reliable. The reliability of the PPS transmitters is awesome. And, the reliability is much more an issue of the transmitter than it is the computer.

Edit: when I got my HUD I think AI's were less reliable, so I saw a fair number of responses from tech/wreck divers that this AI stuff was just another possible point of failure. But with the Perdix and Teric it seems the technology has become 'more' reliable (though I would still dive with redundancy).

Agreed. Back when you bought the HUD, which I assume is the Oceanic DataMask, the tech/wreck divers were way over on the side of points of failure, too often based on assumptions about things.

On the other hand, it's typically a $300-400 upcharge for AI.

Depends on the brand. The AquaLung i200C to i470Tc upgrade is just $110 (plus transmitter, of course). And you need not buy the transmitter initially, so the total costs can be spaced out.

 

[Lostdiver71]

There are also a lot of used transmitters that come up for sale, both of mine were purchased used and I have had no problems with them.

 

[tursiops]

There are also a lot of used transmitters that come up for sale, both of mine were purchased used and I have had no problems with them.

Agreed. I have four, all of them purchased used. $200-225 is a pretty good price, $250 is high.

 

[Pressurehead]

I bought an Aqualung i450T on special last year, it was a display model in a local dive shop, the last one.
Has AI and I had a transmitter from an old Atmos that works with it, and the user can change the battery [which I like], still a few around on special [I saved $$].
Would love a Garmin Mk2 Descent, but can't justify the cost.

 

[Centrals]

There is NO definitive answer for AI or not, it is entirely up to the individual to decide.
I do not use it.

 

[Brett Hatch]

Right, so a hundred bucks or so upcharge on AI-able computer itself, plus ~200 used or ~400 new for the transmitter. Multiply it by two for his wife, and you're talking a lot of money for what is essentially a convenience. I'm not gonna say it's not worthwhile, I have one after all and am happy with it. Just pointing out that since it's kinda expensive and doesn't open up any new kinds of diving, I would personally recommend a new diver to skip on it in lieu of other piece of gear.

Removing a hose is nice, seeing your time-to-surface is nice, automatically logging your SAC on every dive is nice. If those nice-to-haves are worth coughing up for *to you* then go for it . Either way, you'll end up with a computer than can handle any recreational dive.

 

[tursiops]

Right, so a hundred bucks or so upcharge on AI-able computer itself, plus ~200 used or ~400 new for the transmitter. Multiply it by two for his wife, and you're talking a lot of money for what is essentially a convenience. I'm not gonna say it's not worthwhile, I have one after all and am happy with it. Just pointing out that since it's kinda expensive and doesn't open up any new kinds of diving, I would personally recommend a new diver to skip on it in lieu of other piece of gear.

Removing a hose is nice, seeing your time-to-surface is nice, automatically logging your SAC on every dive is nice. If those nice-to-haves are worth coughing up for *to you* then go for it . Either way, you'll end up with a computer than can handle any recreational dive.

OK, I thought you meant the computer alone was a big upcharge.

 

[Centrals]

AI is NOT an upgrade.

 

[ATJ]

It is worth pointing out that there is no "connection" as such to drop out with AI, at least with PPS transmitters (Oceanic, Sheaerwater, etc).

The transmitter simply broadcasts the tank pressure and transmitter ID every 5 or so seconds and the dive computer listens for the broadcast and displays the tank pressure. If the computer is out of range of the signal or there is something in the way (like a body or a head) the computer may not receive the broadcast. The computer continues to "listen" for the broadcast and so as soon as the transmitter is in range again or the obstacle blocking the signal is removed, the computer will be able to receive the signal again.

Most dive computers are quite lenient and will accept a certain number missed broadcasts before they get slightly unhappy (and a few more before getting really unhappy). If the dive computer tells you it has missed a few broadcasts all you need to do is move the computer to a better position.

 

[Grateful head]

What do you people suppose is an expected lifespan of a new dive computer? Based on 20 to 30 dives a year. For me anyway, this is also a consideration. Reliability is a big factor.