owning multiple computers

[Centrals]

How has yet another computer thread become focused on Shearwater? It doesn't feature in the original question!

And I am for using a back-up computer particularly given the OPs regular week long dive trips. I have seen many dives missed on expensive live-aboards all for the sake of a ~$200 back-up device. You can swap to other equipment between dives but not the computer as it has your residual nitrogen.

Dive the conservative zoop, as you are doing now.

#45.
Two is always better than one.

For the OP, use the Zoop and wear the other on your other arm. One day you might need to use your back up to bail out your buddy or yourself underwater!!

 

[Tbar]

#45.

I was aware of when, just not clear how/why, given the simple question in the OP (yes... the reliability discussion...)

 

[Centrals]

I was aware of when, just not clear how/why, given the simple question in the OP (yes... the reliability discussion...)

As Steve_C said in #48, how and why is NOT the reason.
If someone is looking for a beginner computer under $200.00, it won't take long for someone to suggest an $800.00 alternative.

 

[Antmany2k]

I'd say all the OP needs to learn how to do is set the FO2 on both computers, so when he does dive, he can have both set correctly for the gas he's using, so they'll both correctly track his inert gas tissue loading.

ok am going to ask a question at the risk of looking stupid again but its the only way i will learn. so if i remember correctly the FO2 of air is 21%? now i can set that in my computer for more accurate readings of nitrogen buildup/loading/whatever you want to call it.
now the potentially stupid part - if a computer is set to the air setting then it should already at default be calculating at 21% oxygen to 79% nitrogen? i have limited knowledge of Nitrox but from what i have seen in comments around this board is that FO2 settings are more for Nitrox divers as they have to calculate PP02 which changes depending on the mix they have and the % of oxygen in their tank? so FO2 setting would be more if i did Nitrox or at best on air as "good practice for the future" am i right or completely stupid?

 

[jstreetley]

so FO2 setting would be more if i did Nitrox or at best on air as "good practice for the future" am i right or completely stupid?

I have a Suunto Vyper, which should be pretty similar to the Zoop. As far as I understand (though happy to be corrected), there is no difference between diving the computer in air mode or at Nitrox set to 21% O2.

The only thing to be aware of is that you can't freely switch between modes during a dive series (i.e., when it is still showing no-fly countdown), so if you are doing a mix of air and nitrox diving, best to switch it to nitrox and just vary the %age O2.

 

[doctormike]

For a simple recreational warm water diver like me, what would Shearwater do better than my cheapy 6 years old SUUNTO D4?

For some reason, folks seem to get defensive when Shearwater is recommended. Don't understand that. But since you asked:

- Amazing customer support. I have emailed Shearwater on Sunday night and gotten a thoughtful reply in 20 minutes. Their corporate officers are at the dives shows, listening to divers and responding with new products and upgrades. Maybe you have had good luck with Suunto, but do a search here for Suunto customer support stories.

- When the battery dies in some remote location, I can change it in 3 minutes with a universally available AA battery and a quarter. I have had my old Suunto flood after a battery change by a dive shop.

- Incredibly readable and customizable display with a lot of useful information that doesn't require paging through menus like my Suunto used to.

- As I got older, the dim monocolor Suunto display became less and less readable. The Petrel display is awesome.

Yes, I understand. You don't need to spend $800 on a computer when you can get one for $200. You don't need to spend $5000 to go to Truk Lagoon when you can wreck dive in the Keys for $2000. I don't think that I or anyone else here ever implied that you need a Petrel because a cheaper computer won't do the job, and sorry if you got that impression. But there are reasons why a lot of CCR manufacturers use Shearwater electronics, and reliability is one of them.

It's a very good computer made by a very good company, and I appreciate their effort and want to support them in public as much as possible, just like I would in any industry.

 

[dmaziuk]

now the potentially stupid part - if a computer is set to the air setting then it should already at default be calculating at 21% oxygen to 79% nitrogen?

Mine comes with factory-default PO2 of 1.4 and according to the manual "air" is just that at 21% O2. The only difference is in "air mode" it does not show oxtox graph. I think I'd rather have it shown all the time, just for consistent interface, but in practice it doesn't t matter for my shallow single-Al80 reef dives, so...

 

[dmaziuk]

Assuming you have a good SAC rate and decent sized tanks. Most beginning divers I have seen are more often air limited than NDL limited.

ScubaLab "studies" show very clearly that you can come up with profiles that will bend one computer but not the other in only 3 dives. IIRC their dives were 40-50 minutes which is not that hard with a single Al80.

 

[Steve_C]

ScubaLab "studies" show very clearly that you can come up with profiles that will bend one computer but not the other in only 3 dives. IIRC their dives were 40-50 minutes which is not that hard with a single Al80.

By bend I assume you mean get the computer to lock you out because it thinks you were a bad boy/girl while the other computer was completely cleared?

If that is the case I have done it within 2 dives. Usually I clear both but we were last ones up, it was getting a bit rough, and everybody on the boat was waiting for us so they could head home. So did the safety stop for one computer and cleared it, tossed in a couple extra minutes and went up.

 

[dmaziuk]

By bend I assume you mean get the computer to lock you out because it thinks you were a bad boy/girl while the other computer was completely cleared?

By bend I mean they managed to get leonardo to show 1 minute NDL when a300cs was showing 103 minutes. At 30' on dive 4 of the day. I.e. low SAC and twin 120s is not the only way to send one of your computers into deco. A gas-limited beginner diver can do it by picking the right dive profiles for the right pair of computers.