Tell me about dive computers

[fnfalman]

What are so expensive? Dive watch or dive computer?

Some dive watches are barely $100. Some computers aren't much more than that.

Some dive watches go up to around $10,000. I have yet to see a dive computer that's even a third of that.

 

[mtabor]

I love my D4, wear it everyday. Does everything I need for my diving.

 

[EFB]

What are so expensive? Dive watch or dive computer?

Some dive watches are barely $100. Some computers aren't much more than that.

Some dive watches go up to around $10,000. I have yet to see a dive computer that's even a third of that.

I was speaking more of the computer than the watch (though I can now see there is a wide price range for both).

 

[TSandM]

As far as how important they are to have -- you can absolutely dive tables. People did it for ages, and it still works. The problem with tables is that they are designed for, and work best with square profile dives, like wreck diving. The tables assume you will load nitrogen at the rate you do at the deepest depth of the dive for the entire bottom time, and whether it's boat or shore diving, many dives just aren't like that. When you shore dive, you start shallow and end shallow, and often spend very little time at your maximum depth, but the table doesn't know that. Many boat dives, for example on walls, may start deep and work gradually to the surface -- again, the table doesn't give you any kind of credit for the time you spent shallow. What this means in practice is that table dives will be considerably shorter than computer dives, and some dives won't be possible at all. (One of our most common shore dives here won't fit on any tables at all.)

If you are traveling, and diving in groups, you are going to annoy everyone, including the dive guide, if you are diving tables, because they often want the entire group to surface if any member needs to do so.

Dive computer use has become so ubiquitous that some agencies are dropping the requirement to teach tables AT ALL in OW.

One piece of advice, though -- Buying a dive computer does not absolve you from the obligation to understand what is happening with nitrogen dynamics during your dive.

 

[PatW]

Well, the problem with tables is they figure that you go down to your max depth, stay there and surface.

But in most dives, you go down to a max depth and slowly rise.

A dive computer gives you "credit" for the fact that you are doing a multi level profile instead of hanging out at maximum depth the whole time. The computer also keeps track of your surface interval and factors in your residual nitrogen for you next dive.

Most computers will also do Nitrox.

For me, I have found that air intergrated computers are not that much of an advantage. My computer will estimate the minutes of air supply I have left based on its calculation of my consumption. The computer I have used is pretty slow to respond to the change in consumption at shallower depths making its estimation of air minutes remaining hopelessly inaccurate.

Computers are a great tool. It is important to retain your understanding of the whole process though. Computers can not keep you from doing something stupid.

If your dives are pretty much one level dives, you can probably get along fine without a computer.

 

[DivemasterDennis]

Sorry no one actually answered you question simply . May I? A dive computer is a battery powered device which offers you a digital read out of your current depth, maximum depth on the current dive, time since submerging, and no decompression time remaining at your current depth. It will also offer some form of warning of your approach to reaching your ndl through pixels or other graph. Most will count down a three minute safety stop. Out of the water, they continue to monitor off gassing through "pixel reduction" graphing or the equivalent. My wife and I always dive with a computer, as well as a watch. I see no need to delay use until a certain number of dives is reached. A computer offers the best constant information feedback on a dive with little or no effort on your part, and they are really easy to read. Computers were fairly new when I began diving, and I have dove with one on every dive, including my open water certification dives. I prefer my computer on my gauge console, where I also have my air gauge (spg) and a compass. That is a great set up for recreational diving. I focus on the dive, not tinkering with complex dials and whistles. Computers also maximize bottom time through constant recalculation of ndl based upon changes in depth during the dive. Get a good, simple, easy to read computer as soon as you can.
DivemasterDennis

 

[sgatke]

Personally, I purchased a dive computer while taking my Advanced Open Water classes.
As other posters have already mentioned, a dive computer is very close to a "need to have" tool. If you ever go on a liveaboard or just multiple days of diving at a resort, you will be very happy you got yourself a computer.
The dive computer keeps track of your diving profiles and makes sure that you are able to stay inside the limits.
The computer I ended up with, was a Suunto D4. The price of the computer was acceptable and I find it easy to use.
There is an optional USB cable available. This makes it possible to download your dive profiles to your personal computer which, for me, is great value. Please note that the price of the cable is ridiculously high - I paid something in the region of 70 Euros for the cable (in my opinion it should cost around 10 Euros) - but, I am still happy I bought it.

I have seen several dive locations where the use of a computer is mandatory.

Please note that a lot of divers find the algorhitms of the Suunto computers very conservative. It has not limited my diving in any ways yet, but your mileage may vary.

 

[Cixelsyd]

Like others have mentioned, if you don't have a computer, you'll be diving tables. That's fine, but the tables are somewhat of a blunt instrument. Because there is no way to accurately track your depth throughout the dive manually, the tables error on the side of safety by assuming you spent the entire dive at your max depth loading nitrogen. It assumes sort of the "worst case scenario" as far as depth to make sure you stay safe. Because of this, your ending pressure group on the tables will likely be calculated higher than the amount of nitrogen actually in your tissues. This is fine until you want to make a second dive and find that you either can't do the dive at all or your dive is extremely restricted in time or depth because you'd violate the no-decompression limits on the table during your second dive otherwise.

The computer is much more precise. It continuously samples your depth and constantly recalculates the amount of nitrogen being loaded or off-gassed by your body at the current depth. Because of this, the computer would accurately show that you loaded less nitrogen into your body than the tables would. For example, if you went deep for 10 minutes and then gradually worked your way up up to a shallower part of the wreck or reef during next 20, the computer would track this and would give you credit for the shallower portions of the dive in its nitrogen calculations, while the table would force you to assume you spent the entire 30 minutes at max depth. On your second dive and beyond, your computer would give you a much more accurate view of the time and depth you are safely allowed than a table.

Basically, the short version is this: You can dive tables from now until eternity and you'll be safe the whole time, but your dives will be shorter. Computers give you a more accurate picture of your current nitrogen levels and will give your more time and depth on repetitive dive.

 

[Amphiprion]

While it is always important to understand tables, many recreational dives do not have a square profile. Because of this, a dive computer can come in handy to increase your dive time in relation to your no decompression limit. I have two dive computers. One of them is an oceanic geo that I purchased on sale at scubatoys. It is a simple nitrox dive computer which doubles as a watch. It is not air integrated. I wear this computer as a watch when I go on vacation as its loss would set me back less than loosing my breitling. While it is bigger than a casio, it is still small enough to function as a normal digital watch on the surface.

I also have a VR3 dive computer for technical diving. It is big and would not function well as a watch. There is legitimate debate as to whether a dive computer is truly needed in technical diving as there is much more focus on planning the dive and diving the plan due to gas management considerations. Nevertheless, I find mine useful when I am wall diving and I (my dive team) choose not to stay at my max planned depth for my maximum planned duration. In this case, having a computer may mean clearing deco earlier.

If I were a new diver, I would choose the oceanic geo as a small nitrox computer that can double as a vacation timepiece. I would choose a nitrox computer over an air computer as many divers decide to take this class shortly after open water, often in conjunction with advanced open water.

Many new divers are overly enthusiastic when it comes to the purchase of a dive computer and end up with wireless air integrated full color high definition displays. While there is nothing wrong with these computers per se, they add an extra level of complexity and can cost as much as an extended weekend trip to cozumel.

 

[Frosty]

EFB- Theres a lot of people with a whole heap more scuba experience than me. BUT I've just finished going through the exact selection process It looks like you are about to go on.
I feel I must offer you advice based on what I did (wrong)
Before deciding if wrist mount or console type computer is what you want to dive with. Borrow/hire the different types.
Otherwise you may find you are using a computer style/type you hate.
-I was utterly convinced that wrist mount was the only way to go Untill I wasted my money and found I hated it
I now have a wisdom 2 Air integrated console type and I love it.