Dive Computers---Not if, But When!

[MarcHall]

Dive computers fail or malfunction.

So it's only a Question of when and how to prepare for that time.

Which is better? :
1. Dive with one computer and back up with an analog depth and pressure gauge.

2. To dive with two computers and back up with an analog depth and pressure gauge.

3. Or dive with two air integrated computers. (Take the analog depth and pressure gauges along to use if (when) one of the computers malfunction).

Yes I do refer to tables when dive planning---but with repetitive dives on multidays---I am off the tables by the second or third dive.

On a pool test dive with my new Uwatec Air Z nitrox wrist—it malfunctioned. It is now at ScubaPro in California. This was my first dive with it.

I am planning on getting a Suunto Vytec air integrated or Vyper not air integrated. My husband thinks getting a backup computer for each of us is over kill.

Yes, I want to be prepared!

Going to Cozumel the end of April---can hardly wait and I want to dive and not sit out if (when) my one computer (and only computer) goes south on me.

Thanks! An AZ Diver.

Which is better? :

Dive with no computer.

Learn how to plan proper ascents and use a simple bottom timer like the Uwatec Digital Bottom Timer.

Dive as a team so if your Bottom Timer does fail you can rely on your backup which just happens to be on your team members arm.

Marc Hall
www.enjoythedive.com

 

[azsilver]

Which is better? :

Dive with no computer.

www.enjoythedive.com

MarcHall, that would be great---if it were just that simple! But if you solely use dive tables and do multiple dives in a day you are off the tables during the second dive. Unless you have real long SIT or you DECO dive. Computers allow your dive profile to be calculated at multiple depths during a single dive with the algorithms ....as you shallow up and do your safety stop. I do use my tables to dive plan so I know what is going on.

I like to use all the tools available including electronic dive computers!

Thanks---Tables are good to use and know as a Backup.

An AZ Diver

 

[mempilot]

Tables are good to use and know as a Backup.

An AZ Diver

Yep, use a computer, back it up with a bottom timer or watch. Know the table value for your dive before you get wet. If you're doing multiple gasses, then go with the tables and a bottom timer.

 

[MarcHall]

MarcHall, that would be great---if it were just that simple! But if you solely use dive tables and do multiple dives in a day you are off the tables during the second dive. Unless you have real long SIT or you DECO dive. Computers allow your dive profile to be calculated at multiple depths during a single dive with the algorithms ....as you shallow up and do your safety stop. I do use my tables to dive plan so I know what is going on.

I like to use all the tools available including electronic dive computers!

Thanks---Tables are good to use and know as a Backup.

An AZ Diver

AZ Diver

It is that simple and I can assure that on my single day multi-dive trips and on multi-day multi-dive trips I spend minimal time sitting on the boat or the shore as the case may be.

I also take into account multi-level diving during my dives.

As far as deco, every dive is a deco dive as every ascent needs to be done at proper rate. At a minimum I spend 3 mins ascending from 30 feet to the surface. The actual ascent rate from the bottom to the surface is dictated by the parameters of the dive.

In comparsion to how I dive now, I spend much more usuable time in the water doing actual dives then I did when I used Suunto, Uwatec, and/or Oceanic Computers.

By diving with the simple tools and not depending on a dive computer I select the algorithm/rules that I dive with and not the manufactuer (and its legal department) of the dive computer.

Enjoy

Marc Hall
www.enjoythedive.com

 

[azsilver]

AZ Diver

As far as deco, every dive is a deco dive as every ascent needs to be done at proper rate. At a minimum I spend 3 mins ascending from 30 feet to the surface. The actual ascent rate from the bottom to the surface is dictated by the parameters of the dive.

Marc Hall
www.enjoythedive.com

Marc,

What happens for example if you were to dive in Cozumel and the dive Op tells you they do not allow DECO diving?

What do you do?

Just find a Dive operation that does? I just want to be informed.

I check out your website----very informative!

Thanks, AZ diver

 

[mempilot]

Marc,

What happens for example if you were to dive in Cozumel and the dive Op tells you they do not allow DECO diving?

What do you do?

Just find a Dive operation that does? I just want to be informed.

I check out your website----very informative!

Thanks, AZ diver

Marc means that even NDL dives are still deco dives. The NDL table times are based on proper descent and ascent rates which take into account time for ongassing and offgassing at depths other than max depth. You are decompressing on your way up from a NDL table dive. You just don't need to make mandatory stops at given depths for given times. The 10-15' stop for 3 minutes is now called a safety stop to allow for any indescretions in depth or time.

Use your computer, use the tables, it doesn't really matter. But you should always be able to go into manual reversion (back to the tables) in the event of a failure. Marc just takes that failure point out of diving. Problem is, people are failure points in their diving as well. People make mistakes, computer's don't. People fail, computers fail. I'll always use a computer, and back it up with manual reversion. Write the table values on a slate and take em with for your intended depth and time and the next deeper depth and time. You'll know where your at if you have a watch or bottom timer, but you won't have to do multi-level calculations since the cx will do them for you.

 

[azsilver]

but you won't have to do multi-level calculations since the cx will do them for you.

Thanks for the information--I understand the intent that all dives are in reality DECO dives--but the logistics of diving with a Dive Op and having them telling you they do not allow DECO diving (Which I have been told).

Do some dive operations allow DECO diving if you are trained?

Just curious!

Thanks, AZ diver

 

[MarcHall]

Marc,

What happens for example if you were to dive in Cozumel and the dive Op tells you they do not allow DECO diving?

What do you do?

Just find a Dive operation that does? I just want to be informed.

I check out your website----very informative!

Thanks, AZ diver

Mempilot somewhat covered it.

But...

#1 Every dive is a deco dive.

Every dive requires a proper ascent. The Cozumel dive operator is not going to want you to ascend from your wall dive at 300 feet/min.

Depending on the depth but within what would commonly be called No Decompression Limits or NDL I would ascend at 30 feet/min to somewhere between 50 and 30 feet and then ascend at 10feet/min. The 10 feet/min ascent would be best done at a constant pace but could also be done in the form of stops say at 30 feet, 20 feet and 10 feet.

If the dive operator would not allow me to dive in what I consider a safe manner, I would simply find another dive operation or another dive destination. It's pretty black and
white. I also believe in not diving below 100 feet without Helium in the tanks, if Helium is not available then I won't be doing the dive.

#2 Knowing you dive profile

Although I do carry a few notes regarding deco in my wet notes, I seldom reference them as its all in my head and
thats for dives within the recreational limits and for deeper technical dives.

I also do monitor my dives during the course of the dive. It just part of diving intelligently. It does not at all distract from the fun of the dive or from performing other activities like shooting video or scootering or scootering and shooting video :-> In fact it makes dives more enjoyable to know that how much longer your gas should last or if you are consuming it at a greater rate then normal or that I don't need to depend on a computer that may fail in order to get safely home.


Take care

Marc Hall
www.enjoythedive.com

 

[mempilot]

#2 Knowing you dive profile

Although I do carry a few notes regarding deco in my wet notes, I seldom reference them as its all in my head and
thats for dives within the recreational limits and for deeper technical dives.

I also do monitor my dives during the course of the dive. It just part of diving intelligently.

OK, I'll bite on this. I agree, one must know their dive profile and stick to it. What I don't agree with is memorizing tables, especially for deeper technical dives. Now, while you won't dive deeper than 100' on Nitrox, 99.9% of diver's do. Let's not get into trimix diving in this thread. Having MOD's and NDL tables in your head for deep dives goes out the door when narcosis sets in. That's why we mark our tanks with big MOD numbers and use slates, wetnotes, or computers.

Again, Marc, I know you've limited your N2 by going He below 100, but even with a clear head, relying on memorized tables is a bad idea. The problem is, you run the wrong schedule once by mistake and you're in trouble. Why not just pull out the wetnotes on every dive.

I'm sure you don't teach that technique to your students.

I fly for a living. We use checklists for every flight. Some checklists are short, some are long. After flying the same aircraft for many years up to 6 legs a day, one tends to know the checklist by heart. But, we still read them, because missing one item can kill ya.

 

[mempilot]

Do some dive operations allow DECO diving if you are trained?

Just curious!

Thanks, AZ diver

Some operators who have a trained captain and crew will let trained divers do deco dives. These dives often involve having safety divers, dive plans that get turned into the captain, and additional support equipment. The deco hangs often require more time than the bottom time and therefore require procedures for communicating with the surface; hence lift bags, SMB, safety divers, etc... You will often have to charter the boat for the day, and possibly only complete one dive per day depending on your profile. The boat I dive off of let's me put together deco trips on days when no other recreational divers will be on board. Then my buddies and I go where we want and do a single dive that often lasts over half a day from departure to arrival at the dock.

Light deco by trained divers is done on regular charter boats with the approval of the crew, but this is much different than regular deco diving. Most of your resort operators won't allow it. This may include going over the NDL by only a few minutes requiring a short deco stop in the 30' range in addition to the safety stop. Typically, there is no reason for this. We do it durring lobster season when we find a stash of bugs at the end of the dive and spend a few extra minutes harvesting. We only do this when carrying extra gas.

Go ahead and do the training. It teaches you a lot about diving that is valuable to even the recreational diver. You'll be more confident and a better diver for it.