Affordable Dive Computers

[Belzelbub]

Also true if using only one computer.

I don’t understand what you are saying here. This was in response to taking both computers on all dives to ensure accurate diving history.

How can you take both computers if you only use one?

I would suggest not purchasing 2 computers with the same algorithm, as the OP says he wants to do. Wouldn't it be better to have 2 computers with different algorithms, assuming 1 to be less conservative than the other?

If you already have one, and purchase another, then having different algorithms may be unavoidable. However, if buying both at the same time, looking for computers that run the same algorithm is helpful. If you want to run the primary mire conservative, then that would be an option. Kind of like a Plan A, Plan B thing. At least this way, they’ll probably tracking similarly, though buffer may be different.

With different algorithms, dive 1 will probably be close, but subsequent dives may differ significantly. That could be confusing.

OR, as suggested by others, get 2 of the same, less conservative computers, and hope the diver pays attention while he/she is diving?

Regardless of conservatism, I hope all divers using computers pay attention to them. I know that’s not always the case, but it should be. I don’t get why this is included in the OR as it should apply whether the computers are running the same algorithm or different.

When I first started diving with only a handful of dives under my weight belt, if I would have had 2 computers and one locked on me and one didn't, I probably would have been worrying about which computer knew me best......no, I probably would have jumped in to dive again!!

Doesn’t this counteract your advice to use two different algorithms? At least for new divers.

If two computers running different algorithms give two different results on a dive, that’s somewhat expected. If two computers running the same algorithm are giving different results, that’s not expected and may be an indicator that one has failed. Looking at the settings and onboard log may yield clues to which one knows you better.

 

[ryan666]

Using my garmin g1. Very happy with that.

 

[Vertologist]

An entry level computer, such as the Peregrine, will make a wonderfull 2nd to a perdix one day. Buy once, cry once. I use my Peregrine as a primary, to the used Zoop that came with my 1st reg set. Diff algo I know, but it is a redundant computer.

This is my hope for one day. I'm new, but sprang for a Peregrine after OW and dive that. Maybe one day I'll get air integration in a Perdix and use the Peregrine as backup!

 

[Alex_Garland]

I believe the best practice is to purchase two dive computers so that if one dies you have the other one just in case so that you can still do more dives. I was wondering how to decide what two dive watches I can purchase together. I would like to buy two DIFFERENT "affordable" dive watches but my understanding is that the watches have different dive computer algorithms.

This thread caught my eye, because I am considering purchasing a second computer for the sake of redundancy. I have a couple of trips coming up, Little Cayman in July, and the Aqua Cat in the Bahamas for New Year's, in which a computer failure with no back-up would be problematic.

For the past eight years I've been diving with just an Oceanic OCS on the DSAT algorithm. It has been a good, solid computer that has kept me alive and healthy. My only gripe is the incessant beeping; this model has a temperamental assent warning. I'm not a fan of big and bulky; I like that this one is just about small enough to be worn as a wrist watch, and I would prefer a similar size with my second computer.

I am considering the Aqua Lung i470tc, because the design is similar, and according to my local dive shop, Aqua Lung uses algorithms that are close to those used by Oceanic. I also like that this model is a little more state-of-the-art with Bluetooth capability. Though I'm not currently interested in air integration, I like that this model has that capability, should I change my mind and decide to splurge on a transmitter.

And yet, after reading Brett Hatch's comments about the Shearwater Peregrine, I did a bit of research and am intrigued. Though I dislike the idea of a bulky square computer on my wrist, the full-color screen on this one does look attractive. I also like the USB re-charging capability and that it has a vibrating alert option. But I wonder if the algorithm is different enough from DSAT to be a problem.

The price point on both of these is about the same. Thoughts?

 

[Vertologist]

I looked for a bigger screen just so I could see it! (My close vision is not what it was.) Though I don't have much dive experience, I've been pleased with the Peregrine, its large readable screen and its vibrating alerts. No air integration, though.

 

[inquis]

But I wonder if the algorithm is different enough from DSAT to be a problem.

The peregrine can be configured to be similar to the DSAT times by using the x/95 gradient factor (which controls the conservatism). (The first number is only for mandatory decompression dives.)

 

[Alex_Garland]

The peregrine can be configured to be similar to the DSAT times by using the x/95 gradient factor (which controls the conservatism). (The first number is only for mandatory decompression dives.)

That is helpful to know, thanks. And to complicate matters further, I'm getting interested in the Shearwater Teric too. Though the price point is way higher than I'd ideally want, the Teric seems like a computer that combines the best features from the Aqua Lung i470tc and the Shearwater Peregrine. Do you know if the Teric's algorithm can be similarly configured to be close to DSAT?

 

[Hoag]

This thread caught my eye, because I am considering purchasing a second computer for the sake of redundancy. I have a couple of trips coming up, Little Cayman in July, and the Aqua Cat in the Bahamas for New Year's, in which a computer failure with no back-up would be problematic.

For the past eight years I've been diving with just an Oceanic OCS on the DSAT algorithm. It has been a good, solid computer that has kept me alive and healthy. My only gripe is the incessant beeping; this model has a temperamental assent warning. I'm not a fan of big and bulky; I like that this one is just about small enough to be worn as a wrist watch, and I would prefer a similar size with my second computer.

I am considering the Aqua Lung i470tc, because the design is similar, and according to my local dive shop, Aqua Lung uses algorithms that are close to those used by Oceanic. I also like that this model is a little more state-of-the-art with Bluetooth capability. Though I'm not currently interested in air integration, I like that this model has that capability, should I change my mind and decide to splurge on a transmitter.

And yet, after reading Brett Hatch's comments about the Shearwater Peregrine, I did a bit of research and am intrigued. Though I dislike the idea of a bulky square computer on my wrist, the full-color screen on this one does look attractive. I also like the USB re-charging capability and that it has a vibrating alert option. But I wonder if the algorithm is different enough from DSAT to be a problem.

The price point on both of these is about the same. Thoughts?

I was on the Aquacat and had a computer failure. I aborted the dive and returned to the boat. After the other divers were back on the boat, the crew were able to swap out a dive computer that they had available and I only lost the dive that I had to abort. I have had redundency ever since then. The crew were great, and got me back in the water for the next dive, but I would rather be self sufficient.

 

[BoltSnap]

the crew were able to swap out a dive computer that they had available and I only lost the dive that I had to abort

You mean you just continued to dive with a fresh new dive computer that didn't account for your residual nitrogen from prior dives as if it were your first dive in the trip?

 

[boulderjohn]

It is useful to learn how to use the dive tables even if you won't ever use them again. It teaches you the theory behind what your dive computer is doing for you.

Since this old thread is being read by some people, I just want to make several summary points, including a couple that were not made earlier.

• In reference to the quoted post above, learning tables does not teach you the theory behind what the dive computer is doing for you. That mistaken belief comes from the fact that many instructors taught decompression theory at the same time they taught the tables, and people naturally put the two together. They are separate issues. You can teach the theory at the same time you teach the computers just as easily.
• The overwhelming majority of computer-based dives today are multi-level. Multi-level dives usually exceed table limits for time. Consequently, if your computer goes bad during or after dive #1, you cannot use tables for dive #2.
• There is no value whatsoever in using two different algorithms for your primary and secondary computers. This is especially true if one of them locks you out if it is violated. That means you must follow that one even if you prefer the other.
• A user replaceable battery with the easiest possible process for replacement is a valuable trait in a computer.