Do I need a backup computer?

[Diver Dennis]

I have about 200 dives on my D9 with no problems. I solo a lot so I do have a back up Cobra, not wireless.

 

[drbill]

I don't... and probably won't... dive with an air-integrated computer.

I have had my primary computer fail (battery dead while reading 39% remaining life) while on a deco dive. After five decades, I pretty much know my profiles and how much deco I need so I was able to use my analog devices to comfortably satisfy the deco obligation.

I do believe a backup computer or bottom timer is a good idea.

 

[fppf]

From what I read the manual says that each time the transmitter is power cycled the computer needs to relearn the code.

 

[geraldp]

I just got a D9 with wireless transmitter. Should I have a backup computer on me too? I have read that some divers are doing so.

I understand that perhaps one as a spare may be good....

My first purchase when I started diving was the Suunto Cobra (this was before the Vytec came out and long before the D9 became available). Having everything in one (SPG, Depth Guage, Timer, + computer) bothered me, so I added an analog SPG at the end of a hose. It dawned on me that the SPG by itself is only part of the equation, so I added to that a depth guage. Then I realized that the SPG and depth guage didn't fully help unless you also had a bottom timer. It was about then, as a new diver, that I started realizing how cluttered I was having yet another hose dangling off of me. Everytime I looked for my Cobra I was grabbing either my SPG or my Octo, and it was just stressing me out. So I removed the extra hose and along with it a stressor that I didn't need.

I had several thought processes on backups to my AI computer. My first assumption is that we're talking recreational diving. The other assumption is that your D9 isn't a lemon and the chances of further problems are relatively low:

If your Air Integrated computer fails you always simply call the dive, get your buddies attention and then let him/her help you to the surface. This should work no matter where you are in your dive cycle, even if you're low on air or close to to your NDL. To me it doesn't make sense to spend an additional $700-$1000 for a proper backup just so you can spend a few more minutes on the bottom if your primary computer fails in the middle of a dive.

If (as you stated in another post money is no object then a backup non-wireless AI computer would be nice to have, even if you have it strapped off somewhere (like on your tank) so you could access it if your D9 fails. The purists would argue for an analog SPG, a depth guage, and a bottom timer, which is another option. But then if you don't have your tables memorized you'd better bring them down with you as well.

The final argument that I like to spell out is if your on a tropical dive vacation somewhere (far away from your LDS and not near a rental area) and your computer fails, then you don't want to ruin your vacation. In the end, on my limited budget, is where I finally came up with my current solution... I have an analog SPG, Depth Guage, and Bottom Timer, along with a dive table slate in my save-a-dive kit. It's not the optimal solution, but it would allow me go on to do consecutive dives if my Cobra goes belly up.

Jerry

 

[CompuDude]

If your Air Integrated computer fails you always simply call the dive, get your buddies attention and then let him/her help you to the surface. This should work no matter where you are in your dive cycle, even if you're low on air or close to to your NDL. To me it doesn't make sense to spend an additional $700-$1000 for a proper backup just so you can spend a few more minutes on the bottom if your primary computer fails in the middle of a dive.

"Proper backup"? It IS crazy to spend $700-1000 on a BACKUP computer. Get the cheapest comp made by the same vendor as your primary, no AI needed. Make sure you have an analog SPG available, even if you don't dive with it attached, so you can swap it in the event of a problem. Then you're good to go... if you have no problems with the primary comp, you're set, if it fails, you have the backup comp, which has been with you on every dive, so all of your repetitive dive and surface interval info is intact and ready to rock and roll.

I have an expensive wireless AI primary computer. BUT, should it fail, I'm ok for gas readings because I have an analog SPG at all times. Where I would have issues is if I was diving beyond the capabilities of tables and on the 3rd or 4th dive of the day with more planned. Then I would need historical info on tissue saturation that was lost with my primary comp. That's why I intend to pick up the cheapest Uwatec puck-style computer I can find at some point soon, and start leaving it in my pocket at all times. No need for another spendy AI computer, just a small, inexpensive backup from the same company (to maintain similar algorithms).

 

[fppf]

"It IS crazy to spend $700-1000 on a BACKUP computer"

Why? I just spent $5000 on a dive trip. Add a D100, Ikelite housing, Strobe, and all the other gear, whats another $700?

 

[aowdan]

won't say what comp i use, but i had a serious violation on my 3rd dive with it (current and sea state contributed to this) o got locked out for 24 hours, but for some unknown reason i had brought my wifes regs and guages so i got to complete the other dive for the day. after that 24 hours, it just didn't want to work right. after 2 weeks it magically started working again. i did a series of shallow dives with the comp and spg, no problems.

this has been said before...i now have a first stage with 2 HP ports and run an analog spg on EVERY dive, even cleaning boat hulls. also i have my wrist watch, a watch attached to my comp, and my tables in a pocket. then i also carry a buddy with me.
i love having a buddy, but, in my opinion, self rescue is MY first priority.
dano

 

[Eskasi]

"It IS crazy to spend $700-1000 on a BACKUP computer"

Why? I just spent $5000 on a dive trip. Add a D100, Ikelite housing, Strobe, and all the other gear, whats another $700?

Sigh...I have resigned to buying a backup....and attaching it to the other HP port on my first stage. Will probably get another Suunto ...perhaps a Cobra. I am just wondering if it is overkill? kinda makes the D9 wireless seem like a accessory/fashion statement.

I agree though...spent almost $4000 on brand new gear including the D9. 10% more isnt going to make too much difference at this point. Besides, I am off to Palermo, Malta, UAE and Sharm (with side trips to other non dive areas) for over a month...would hate for a failure to occur and ruin even a precious day of vacation diving. (I will do an AOW class then too).

 

[Solo1mick]

I just had to buy a back up spg. I have a D9 AI after 10 dives failure (granted I found out it was the DPV causing it)
Dive 15 failure, but re connected back at surface.
Dive 17 Failure and never worked again.
Sent it back to Suunto and to there credit replaced it within 7 days no questions asked.
So I did the logical thing, instead of wasting $50 on a dive that lasts 10 minutes because of future failures I spent $49 on a analog spg. I always wear my watch on other wrist so problem solved.

 

[NiNbubble]

When it connects the next time, say when the air is turned on, isn't it the same code? I need you (someone!) to explain more about the transmitter problem... I have a D9, and on a recent trip, there were two other D9s on the boat. From the first day, each computer used a different code, and until one day when I changed mine on purpose, they stayed the same. For example, I was on 22, next guy was on 26 and third guy on 05.

What is the big deal? that's what I don't get. Every time I turned my tank off and turned it back on, I got the same code...

Note that I do carry an SPG. And you have to admit, the D9 is very sexy!

kari

Yeah, when you shut down and reconnect, the code SHOULD be the same. The problem with the Suunto transmitter is that the code-changing procedure is turning the pressure below 15 bars and quicly (within 20 secs) turn it up again. Now, when you turn down the pressure, it's possible to have small fluctuations in the HP that unwantingly resets transmission codes. The Oceanic approach of hardcoding the transmission frequency in each transmitter according to its serial# is indeed the way to go...