Computer question

[dflaher]

Timely post for me because I am ALSO going on a liveaboard soon (I leave tonight!) and have no backup computer. Mea culpa. I guess I will need to, for this trip, roll the dice and hope that 1) mine doesn't stop working or 2) I can rent a backup from the LOB operator.

For future reference, my dive computer is a hose-mounted air-integrated one. What type of backup should I purchase? If I buy a simple wrist-mounted one, and my primary fails, I won't have any way of determining gas remaining, unless the backup has a transmitter, correct? Or do I purchase an inexpensive SPG to go along with an inexpensive wrist mount?

My wife, who is not diving with me on this trip, also has a hose-mounted air-integrated DC. Could I bring that along in the event mine fails? But then I would have to dive with 2 hose mounted DCs simultaneously so that both DCs have the same nitrogen loading. How would I do that?

Thanks.

 

[outofofficebrb]

Timely post for me because I am ALSO going on a liveaboard soon (I leave tonight!) and have no backup computer. Mea culpa. I guess I will need to, for this trip, roll the dice and hope that 1) mine doesn't stop working or 2) I can rent a backup from the LOB operator.

For future reference, my dive computer is a hose-mounted air-integrated one. What type of backup should I purchase? If I buy a simple wrist-mounted one, and my primary fails, I won't have any way of determining gas remaining, unless the backup has a transmitter, correct? Or do I purchase an inexpensive SPG to go along with an inexpensive wrist mount?

My wife, who is not diving with me on this trip, also has a hose-mounted air-integrated DC. Could I bring that along in the event mine fails? But then I would have to dive with 2 hose mounted DCs simultaneously so that both DCs have the same nitrogen loading. How would I do that?

Thanks.

For a hose mounted air integrated one, you could get a second dive computer with wireless integration. You could then use either your hose mounted one as your backup and the wrist one as your primary, or continue with your hosed one as your primary - it would depend on which is more liberal or conservative.

I prefer to have a regular, boring SPG and compass on the hose then have a primary air integrated and then a backup. Backups can also be air integrated and can run off the same transmitter if it's compatible so you only have 1 transmitter or it can just be something basic that will work for the diving you need it to work for.

As for diving with 2 hose mounted air integrated DCs....not that practical not to mention the ports you would need for it on your first stage. I have not been a fan of house mounted computers for my own rig for a variety of reasons and part of it is logistics as you just mentioned as it relates to backups and failures. I also don't like computers that need charging, whether hose mounted or wrist.

 

[Aviyes]

I have done 3 LOBs now with a single dive computer without issue. Those that have had their DC fail, were able to get a rental, sometimes at no cost, for use the rest of the trip. They could probably also rent/loan you a SPG/Depth gauge off their rental gear as well. Don't feel like you will be out of luck. All the Caribbean LOBs I've been on the crew are awesome at helping out with the unexpected gear issues.

 

[outofofficebrb]

I have done 3 LOBs now with a single dive computer without issue. Those that have had their DC fail, were able to get a rental, sometimes at no cost, for use the rest of the trip. They could probably also rent/loan you a SPG/Depth gauge off their rental gear as well. Don't feel like you will be out of luck. All the Caribbean LOBs I've been on the crew are awesome at helping out with the unexpected gear issues.

Yes, but unless you had been diving with the rental since dive 1 and also had repetitive dives, that rental would not properly account for your nitrogen load. So you would have to rent one at the start of dive 1. While you haven't had problems (and I haven't either, and I've been on 9 totaling 153 dives...I hope it stays that way), it doesn't mean that it won't happen. In fact, this isn't unique to liveaboards. This could apply for land based diving if you have a lot of repetitive dives. So the question is...how much is it worth it for someone to be able to continue diving and not have to sit out dives, fuss with tables, or deal with a rental computer that they may not be familiar with that they will now have to learn to use with probably no manual available on board? If at a dive shop, you can probably pull one from the internet. I sure don't want to spend precious vacay time figuring that out and to instill confidence that I know what it's telling me during a dive because that screen looks different than when on the surface. I don't know about others, but I generally take time off work, travel a long way, spend a lot of money and time planning my trips and that would be annoying and not acceptable to me.

Maybe that annoyance and risk assessment is different for everyone. The one time I did get close to using my backup was when I was on a dive trip and I got the low battery warning on a non-user replaceable battery the second dive of the trip. It ended up lasting the rest of the trip but I had my backup ready if needed and with all of the proper loading on it.

 

[outofofficebrb]

I dived with a couple from Toronto who both happened to have dive computer problems but not at the same time. He had problems with his while on the land based portion of the trip and she had problems with hers while on the liveaboard with me. She ended up diving with her husband and relying on his computer who was her dive buddy the rest of the dive and then was able to finagle it into working again before one of our other dives. The liveaboard had some rentals or an extra one available so she ended up borrowing a computer from the liveaboard (whether at cost or free is another matter). She wore it on her wrist just in case it died again. Despite her computer still functioning and her having a borrowed one that worked, neither logged the rest of her dive from the point where she piggy backed to her husband's data or had the accumulated tissue data from the diving so far on a 12 day trip so she ended up relying on him for the rest of the dive trip because she wasn't willing to sit out dives because we were in Raja Ampat. I don't blame her...

We had a long discussion about backup dive computers afterwards. Long story short, she decided then and there she was going to get a backup and she understood why I carried 2. There are some on this board that even carry a back up for their backup!

 

[broncobowsher]

Heads up if you pocket a computer and dive with the other. If the primary dies and you pull the backup out of the pocket without paying attention to it for a few days, you may have put the backup in violation and locked it up for a day. Now you are back to where you were without a backup on you.

How much do you HAVE to dive every single dive? Can you accept a day of sunning it and sucking back plenty of adult Kool-Aid? If with a group you may decide to get a spare for the group. If someone kills a computer, kick back and enjoy a day on deck, maybe a little snorkeling, next day back in the action.

Best plan is to make sure you have a fresh battery and do a test dive with it before starting the vacation. Fresh battery and a dive to make sure it stays dry. Computers are generally pretty robust these days. Also helps to know what happens if you do something wrong (operator error) like take it for a dive in gauge mode. I've seen that done on a trip. That took 12 hours to clear. They were lucky. Skip the night dive, wait overnight, in the morning it worked again. So many require 24 hours, some even 48. You really need to read the book on the computer on your computer ahead of time.

 

[shmuggy]

I suggest buying a cheap used one on ebay or a similiar site. Remember- you never know when your battery will skunk you. Hope you have a good time.

 

[dflaher]

I suggest buying a cheap used one on ebay or a similiar site. Remember- you never know when your battery will skunk you. Hope you have a good time.

I think that's what my next step will be. During my recently completed LOB trip, I took an informal poll of divers aboard and about half had back-up computers and half did not. The boat's operator, Explorer Ventures, did have a few on hand that were available if needed. By the way it was a fantastic trip...

Heads up if you pocket a computer and dive with the other. If the primary dies and you pull the backup out of the pocket without paying attention to it for a few days, you may have put the backup in violation and locked it up for a day. Now you are back to where you were without a backup on you.

I see where that could happen if the primary and back-up DCs had significantly different algorithms. Part of my search for a back-up will be one that has either the same or similar algorithm. Thanks.

 

[Hoag]

The last time I was on a LOB, my computer failed. It was mid week and on the first dive of the day. I hit the water & descended as normal. As we got to the wall, I went through a swim through and exited at 108ft. I looked at my computer and the display was blank. I signaled to my buddy that I was OK but my computer had failed. She buddied up with somebody else for the dive and I headed back to the boat. (I did not have a backup computer, but I was able to track my time & depth on my dive watch.) I got back to the boat (It was right above us.), did my safety stop & got back on board without further incident.

After the other divers were back onboard, the crew swapped out my computer for a rental unit. I continued diving with the rental the rest of the week, and although I had one dive which I had to cut short (abort), I didn't miss any dives.

There are a couple things to keep in mind:

• I did not do the night dive the night before, so I had been out of the water for 18+ hours when my computer failed, so although I did have some residual Nitrogen loading, it was fairly minimal. I dove very conservatively that first day with the rental computer, but after that, I accepted it's N2 loading at face value and dove "normally" the rest of the week.
• I now dive with a back-up "just in case". If you don't have a back-up computer, then get a dive watch that will give you as a minimum your depth and bottom time.
  
• Although unlikely, even a new computer can fail. (This was only my 3rd trip with the computer that failed so after only about 50-60 dives.)
• If (when) this happens, remain calm. Communicate with your buddy. Depending on your situation, you may be able to simply ascend to the boat and let your buddy pair up with someone else for the dive or it might be best for you to both go back. Keep in mind, I could see the boat right above me when mine failed.
• The crew wants you to have a good time. Don't be surprised if they come up with some way to get you back in the water.

 

[KenGordon]

Yes, but unless you had been diving with the rental since dive 1 and also had repetitive dives, that rental would not properly account for your nitrogen load. So you would have to rent one at the start of dive 1.

SB’s favourite deco algorithm will have you back at square one each day. Overnight is long enough for the significant tissue compartments to completely off gas. Assuming that is a good model you only need to worry about dives the same day as you change computer.