backup computer

[Chrisk919]

Query to the group whether ditching the console in favor of a lollipop SPG and backup computer is the right way to go?

Ditched the console for a brass&glass SPG clipped in at the hip, and keep the computer on my wrist.

I have a second computer but since it’s algorithm isn’t as configurable as my Shearwater and I’m still REC I usually just leave it in the spares bag and only plan to engage it after a 24h pause if my primary breaks.

 

[ToneNQ]

No clue what this means but it sounds wrong.

Have you ever done a dive where the Surf GF never drops below 99? If not your horizons are narrow, which is fine, but you're ignoring how a lot of people enjoy their diving.

Fringing reefs, even getting up onto a barrier reef, your main limits are air consumption, thermal comfort and the boat skipper. In these cases dissolved gas is irrelevant. You hit sand at 7m, maybe even 12m, you have to navigate 150m to a wall that drops down to 18m. The dive ends when you're low on gas, cold, bored, sun burnt, or the skipper says so. The only things that matter to check are your SPG and the clock. The bulk of divers on the GBR can safely dive this way. Solo photographers, artists, they'll do 90mins, barely move, most only carry a computer because our Recreational Diving Code of Practice mandates a computer for each diver. Whilst I own four and by personal choice I always dive with two Shearwaters, I did learn to dive before computers. A diver can be safe with an old computer with almost no features, or with two vastly different computers and using barely 5% of their functionality. Whilst that isn't my style of diving its fine for many.

 

[LFMarm]

You are at depth when your computer fails. Where do you find your average depth?

I would recreate in SubSurface a profile that is close enough and see what the average depth is. You can always apply a safety factor to the calculated avg depth to be on the safer side.

 

[34109411]

hey guys

so as i start to look into more tec and solo diving i got into the discusion on having a backup dive computer and got curious what peoples opinion were on it
in hopes of starting a helthy discusion why and why. not i wanted to ask what do you do dive

• no backup computer
• with a cheep (sunto zoop or anything like that)
• diving the same computer for primary and backup
• using you old computer after upgrading

is it a overrated thing or is it most important thing in your kit mby its only used for dives below 30 meter or when a deco dive is intended?
hope to here some of your guys thougt on the topic and learn some now things!

don't go crazy about it just get an extra one and stuff it in your pocket. over the year i have a total of 3 computer. I bought a mares quad air 2 years ago and my back up is a mares m1 that i bought in 2006 ! I l also have a zoop that sit in a drawer.

 

[Scuba fryd]

Don't those backup computers make an annoying beeping noise?

well depends on what your using i actuly never hear my buddy but some computers you can turn it off others just vibrate

 

[rhwestfall]

well depends on what your using i actuly never hear my buddy but some computers you can turn it off others just vibrate

That was a joke... you missed it...

 

[Scuba fryd]

That was a joke... you missed it...

........i see that. definitely went over my head

 

[David Carron]

So let's say you are doing a multi-level dive (for the sake of argument, on air). Your maximum depth was 91 feet, but you were there only about 8 minutes before beginning a multi-level ascent. You are at 36 feet when your computer fails after 36 minutes of dive time.

Tell me what you do next, both on that dive and the dive coming up after a 60 minute surface interval.

If I were on my own that's a generally upwards trapezoid so the average depth of 60 feet works pretty well to calculate that, breathing air, I'm a bit borderline for an ndl dive, but nowhere near starting stops at 20 feet. Depending on the exact multi-level profile I'd probably do five minutes at ten feet and call it good. If I were diving with a buddy, I'd probably just follow their ascent.

I wouldn't do another dive after just sixty minutes of surface interval with or without a computer.

 

[halocline]

If you are diving in a situation where the information on the computer is essential to your safely completing a dive, then you need two computers, and they should be running the same algorithm, GFs, etc. This basically includes overhead and decompression diving.

If you are on an expensive dive trip with several dives/day, all recreational NDL dives, you don’t need two computers to be safe, but it sure would suck if a computer failed on the first day of such a trip and you were without one for the rest. That could cost you more than the price of a back up computer.

One thing that every diver should realize is that the border between NDL and mandatory decompression is a fuzzy line, and that there are things a recreational diver can do to increase his/her safety margin when diving near that fuzzy line or when a computer fails mid-dive. Just do what the computer would tell you to do in the early stages of deco, and you can find out what that is by using the planner on the computer prior to a dive or a software planner running a similar algorithm. We’re not talking about complex technical dives here, we’re talking about how the computer behaves when a diver crosses the line from NDL. The first ceiling is almost always at 10 feet, for up to several minutes, and the 2nd ceiling would be at 20 ft for fewer minutes. So when your computer says goodnight mid dive and it’s a somewhat aggressive recreational dive (or a repetitive dive) you could slowly head to 20 feet, stay there for 2-3 minutes, then go to 10 feet, stay there for more than 5 minutes, 10 would be good (you should have the gas) and that is going to clear N2 from pretty much any dive that’s even reasonably close to either side of NDL.

But then you’re done for the day, and if there are several days left on your expensive vacation, you’re pretty limited. Maybe you can sit out for 24 hours and start fresh with a rented computer. Do they even still have the PADI wheel? I used to use that to plan multi level dives.

If I were advising a new diver, I’d say buy a single reliable computer (shearwater makes very well built and not-too-expensive recreational models) and use it, but if you’re going on an expensive trip with multiple dives/day, invest in a back up.

 

[LFMarm]

If you are diving in a situation where the information on the computer is essential to your safely completing a dive, then you need two computers, and they should be running the same algorithm, GFs, etc. This basically includes overhead and decompression diving.

If you are on an expensive dive trip with several dives/day, all recreational NDL dives, you don’t need two computers to be safe, but it sure would suck if a computer failed on the first day of such a trip and you were without one for the rest. That could cost you more than the price of a back up computer.

One thing that every diver should realize is that the border between NDL and mandatory decompression is a fuzzy line, and that there are things a recreational diver can do to increase his/her safety margin when diving near that fuzzy line or when a computer fails mid-dive. Just do what the computer would tell you to do in the early stages of deco, and you can find out what that is by using the planner on the computer prior to a dive or a software planner running a similar algorithm. We’re not talking about complex technical dives here, we’re talking about how the computer behaves when a diver crosses the line from NDL. The first ceiling is almost always at 10 feet, for up to several minutes, and the 2nd ceiling would be at 20 ft for fewer minutes. So when your computer says goodnight mid dive and it’s a somewhat aggressive recreational dive (or a repetitive dive) you could slowly head to 20 feet, stay there for 2-3 minutes, then go to 10 feet, stay there for more than 5 minutes, 10 would be good (you should have the gas) and that is going to clear N2 from pretty much any dive that’s even reasonably close to either side of NDL.

Fully agree with this in-water strategy. In addition, you should be monitoring your NDL for the whole dive so you would know what is your exit profile at the time of computer failure.

But then you’re done for the day, and if there are several days left on your expensive vacation, you’re pretty limited. Maybe you can sit out for 24 hours and start fresh with a rented computer. Do they even still have the PADI wheel? I used to use that to plan multi level dives.

If I were advising a new diver, I’d say buy a single reliable computer (shearwater makes very well built and not-too-expensive recreational models) and use it, but if you’re going on an expensive trip with multiple dives/day, invest in a back up.

Once out of the water, you can easily reconstruct your repetitive dive profile with tables or planning software and figure out what your next NDL profile should look like so that you can keep going with either a borrowed computer or a depth gauge and a bottom timer. Definitely better having a second computer from the start.