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Hi @tbone1004

Not everyone dives, or wants to dive, like you do. I dive mostly rec, often solo, dive an AI primary with a backup computer and SPG. I've used the backup computer a couple of times, the SPG a couple times more, in about 1200 dives, enough for me.

Good diving, Craig

if you dive solo it's a completely different discussion. What is your primary/backup and what were the reasons for using the backup computer?
 
I have thoughts on a couple of things raised in this thread. But, I will start by directly addressing the OP's question:

I had a TX-1. Mine exhibited problems almost immediately. It took a lot of emails and phone calls, but eventually Hollis replaced it with a brand new one. In the meantime, I bought a Perdix AI. I sold the TX-1 as soon as the new one came from Hollis. So, I only ever did a few dives with it. My feelings about it are that it was not any more readable in low viz than my Oceanic Atom 3.0 (which also uses the same transmitter).

I now have a Perdix AI, a Seabear H3 (which runs the same algorithm as the Perdix), and an Oceanic Atom 3.0. I always dive with 2 computers. For recreational dives, I normally use the Seabear and the Atom as backup. For me, I don't see any advantage to the TX-1 (over the Atom) as a backup. The Atom runs DSAT which is as liberal or more liberal than the Perdix or Seabear. For a backup, on NDL dives, that is perfectly fine by me. I don't need my backup to have the same algorithm as my primary. And, actually, it's nice that it doesn't. I dive on boats where they say "no deco". I will dive right to the limit of NDL on the Atom, which will pretty much always put my Perdix or H3 into deco. Then I will ascend based on the Perdix or H3. I can get out and honestly say to the boat crew (if asked) that my Atom did not go into deco. Yet I also have the peace of mind that I did a more conservative ascent than what DSAT calls for.

I prefer the Atom to the TX-1 because it is so much more compact. And the Atom has been stone reliable - unlike the TX-1.

Faced with buying a new TX-1 today, my biggest concern would be whether Hollis would still cover it under warranty (for the life of the warranty) and how long it would take if I did have a warranty issue. When they finally agreed to warranty mine, it still took 2 or 3 months to get a replacement. They said they were having to wait for manufacturing to make some new ones....

In other words, I would just go with a DSAT computer as a backup. Ideally, an AI one, like the Atom. Because a backup for your SPG is nice, if the reason for a backup computer is in case your primary dies and it is AI.


Regarding diving with 1 computer versus 2, here is why I am firmly in the dive with 2 camp: If my computer has an issue on my first dive, as long as I have a 2nd computer on me, I can continue the dive. AND, I can still do my 2nd dive of the day.

I really don't get it when people say "just use tables for your 2nd dive." I can only speak for myself when I say that most of the 1st dives I do, if I then used tables for the 2nd dive, would mean that I didn't get to do the 2nd dive at all. That is because the 1st dive, when examined on "tables" would (very often) work out to having been a deco dive. And the tables would then have me sit out for 24 hours (or however long) because I went into deco. And if the 1st dive didn't work out to have been a deco dive, the 2nd dive would still be so short as to be almost not worth even getting wet. Let's not forget that, if your primary computer dies, you may not actually KNOW exactly how deep your max was or exactly how long your dive was. So, planning for the next dive using tables would be wisely done with some extra conservatism - which makes it even more likely that you'll just sit out.

The tables on which I have trained require you to look up your 1st dive based on the deepest depth that you hit at any point. And then round up to the nearest increment of 10. Some people talk about "well, I was only at 110 for a minute, but most of my dive was at 80, so I will plan the next one based on a first dive to 90" or some other baloney. At that point, you are simply not following your training and you are not using the tables correctly. Not only would I not ever suggest someone else to do that, I would never do that myself.

I am leaving on Monday for a week of wreck and shark diving in NC. 7 days straight. You can bet your a** that I will be using 2 computers on every dive, to make absolutely sure that I don't have to miss any dives or even cut any of them short. This is my "big trip" of the year and I don't want some reason as silly as "I only dived 1 computer, so I had to sit out the afternoon and start diving again the next day" keeping me out of the water.

Regarding having a spare 1st stage - sure, it is nice. But, it seems, from my limited experience, that a lack of a spare 1st stage is almost never going to keep me out of the water. Dive operators seems to almost always have a spare reg around that they will loan or rent. But, if you only have 1 computer and it dies, then even if you can borrow or rent another one, you're probably going to have to at least sit out the rest of the day, for the reasons mentioned above. Assuming you are following your training (as you should do).

If you are a recreational (sport) diver shopping for regs, rather than buy a doubles reg set, I would suggest to buy a normal single tank reg set and then buy a stage/pony bottle set. That way, you have a spare 1st and 2nd, AND you also have the OPTION to carry a pony bottle with you on your dives. And you don't have to buy or futz with any extra hoses, like you might if you are converting a doubles reg set for single tank use. I.e. you might not want to use a 7' hose when diving single tank.
 
If you're just looking for a back-up, you can find a cheaper computer to run in gauge mode as a bottom timer.

Not if you want it to run ZHL+GF (hoping it matches your birdix perfectly). Not if you want AI on it either, it's about half price of a cheapest new DC w/ WAI.

Edit: what Stuart said about warranty. They offer umpteen months from square trade or something, but with no more TX-1s being made you gotta wonder what that's really worth.
 
I prefer the Atom to the TX-1 because it is so much more compact. And the Atom has been stone reliable - unlike the TX-1.

Faced with buying a new TX-1 today, my biggest concern would be whether Hollis would still cover it under warranty (for the life of the warranty) and how long it would take if I did have a warranty issue. When they finally agreed to warranty mine, it still took 2 or 3 months to get a replacement. They said they were having to wait for manufacturing to make some new ones....

In other words, I would just go with a DSAT computer as a backup. Ideally, an AI one, like the Atom. Because a backup for your SPG is nice, if the reason for a backup computer is in case your primary dies and it is AI.

@stuartv - Thank you. This was the answer I was looking for. You have saved me from a potential bad purchase.
 
all this talk of redundancy, yet no one seems to buy into my recommendation of buying a doubles regulator set instead of singles so you have a spare first stage on the dive boat for the same reason with talks of "global service".... curious

I carry a spare first and second stage regulator in my save a dive kit.

Maybe nobody responded because this thread is about a backup computer?
 
Hi @stuartv, exactly the kind of reply I expected from you when I referenced you in my previous post, not many divers with personal experience with the TX1

It's too bad that Oceanic chose to discontinue the Atom 3/3.1. Huish does still service it. The current equivalent model in the line is the OCi, it lists for about $800 without a transmitter.

@Snoweman, if you could find a used Atom 3, it could be a good backup for you. If it ended up failing on you, Oceanic/Huish would replace it for you for $165 Support » Service
 
I carry a spare first and second stage regulator in my save a dive kit.

Maybe nobody responded because this thread is about a backup computer?

it wasn't something I meant to discuss in this thread, but it's interesting on the pieces of equipment people talk about as requiring for proper redundancy and where/when to carry them. Especially when the "two is one, one is none" gets brought up.
 
Hi @stuartv, exactly the kind of reply I expected from you when I referenced you in my previous post, not many divers with personal experience with the TX1

It's too bad that Oceanic chose to discontinue the Atom 3/3.1. Huish does still service it. The current equivalent model in the line is the OCi, it lists for about $800 without a transmitter.

@Snoweman, if you could find a used Atom 3, it could be a good backup for you. If it ended up failing on you, Oceanic/Huish would replace it for you for $165 Support » Service

Yeah..., $360 for a backup AI was in my range. $800+ is getting way past what I want to spend. But, I would hate to spend $360 and not have it work even more than the $800. I guess I will scour eBay to find a better alternative. @stuartv was a big help.
 
it wasn't something I meant to discuss in this thread, but it's interesting on the pieces of equipment people talk about as requiring for proper redundancy and where/when to carry them. Especially when the "two is one, one is none" gets brought up.

I can only assume the tech diver that said that to me was talking about being under water and having two of everything. In that case, he had two second stages with him and a dive buddy. In those circumstances he had at least two regs and two sources of air.
 
There has been an Atom 3.something on the local CL here (Washington, DC) every time I have looked there recently... And for $3XX, I think. They can be found...
 
https://www.shearwater.com/products/peregrine/

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