How long can you stay underwater at 50 feet? To answer this question in the past, a diver would simply reach for his recreational dive tables. As in most technology-dependent activities, however, the state of the art in scuba diving is constantly evolving. These days, it is common to see a diver use his dive computer instead of dive tables to calculate how long he can stay underwater. Some scuba training organizations, such as SDI (Scuba Diving International), even train students to use dive computers during the open water course.
Which is preferable - learning to monitor your dive parameters using a scuba computer or dive tables? Scuba purists argue that all divers should understand how to plan a dive using dive tables because this is how diving has traditionally been taught. Dive tables require no complicated technology - they are not going to run out of batteries underwater and they force the diver to plan his dive ahead of time. Others argue that scuba courses should "get with the times" and teach divers to use modern technology (like dive computers) which they claim a diver is more likely to encounter in a realistic scuba environment. Dive computers can help to maximize dive times, and usually come with alarms to warn the user if he exceeds safe dive parameters.
In my mind, both systems have the same inherent flaw. To use either the recreational dive tables or a computer properly, the diver must familiarize himself with dive planning and operating procedures of his chosen tool, and then implement this knowledge in the dive environment. For example, the vast majority of recreational divers that I meet have completely forgotten how to calculate maximum dive times, surface intervals, and parameters for repetitive dives using the recreational dive tables. The use of recreational dive tables can be a bit confusing. A diver must periodically review dive table calculations to keep his skills sharp.
The fact the dive tables can be confusing sounds like a strong argument for the use of dive computers until you consider that many dive computers are at least as confusing as the dive tables. I have met countless divers who wear computers on their wrists, but have no idea how to plan a dive, access the logbook, or even read the display on the computers. Part of safe diving is planning the dive ahead of time and then following the plan. It is not enough to simply strap a computer onto your wrist, dive, and then surface asking what the words "DECO" meant on the display and why this was followed by the number 7. Just like tables, dive computers are useless unless used properly.
Both systems work, and work well. A diver can engage in safe recreational diving using either a computer or the dive tables. Instead of arguing for one system or the other, I would instead like to make an impassioned plea that divers use one of these two systems. I have observed certified divers who are trained to use the tables diving without planning their maximum dive time and depth, and without an underwater timing device. These divers rationalize by saying that they don't remember how to use their dive tables, that they lost their tables, that they couldn't be bothered to buy a $20 watch, or that they don't want to do "work" on vacation. I also have met divers who were trained to dive with scuba computers diving without them because computers are simply too expensive to buy or rent.
As an instructor and guide, I am open-minded as to which dive planning system to use. What bothers me is when certified divers are willing to dive without the tools and knowledge to plan and monitor their dives. When deciding what scuba organization to train with, a diver should consider which dive planning system that organization teaches, and whether he is likely to use that system. If a diver chooses to plan his dives with the tables, he has a responsibility to own an underwater timing device, a depth gauge, and his own set of dive tables, which he must understand and use before every dive. A diver who chooses to use a computer has the responsibility to learn to use its basic planning functions, alarms, and display. Tables and computers both work well - but only if you use them.
Speak up! Do you think divers should be taught to use dive tables or computers during the open water course?
Image copyright istockphoto.com, JodiJacobson
Comments
I think you said it right: It doesn’t matter which of the two you are taught, or even if you are taught in both ways if you don’t use it in a proper way…..
There’s an app for that! Baltic Deco Planner is very simple to use yet all the planner anyone would need. Although geared fo the tech diver recreational divers will find it very user friendly. Having right on your phone is a great convenience too. Dive table can be emailed to yourself and gives way to understand gas management info. by just spinning iPhone “wheels” you can play around with adjusting time/depth calculations. Well worth the $50.
IMO Any diver should always maintain his dive table skills. They are your backup if your dive computer fails and even when using a computer they give you an estimate. A computer, because of its incremental calculations, will always give you more diving time than a table calculation, but if these two times diverge too much you know something is off.
my instructor tought us both and i have a good old preasure gauge along with my computor just in case my computor goes down i can go back to my time piece and gauge and can cotinue to enjoy any dive safely. my personal faith on electronics only goes so far so i believe everyone should learn the dive tables come on there not hard at all.
Just wanted to post a correction to Fred’s post. Baltic Deco Planner is 17$, not 50$.
I’m only just learning and only had one theory on tables but never took notes and was not given any examples to work out on hand outs so now I feel I’ve got a mental block on tables!
I can’t believe Sandra’s comments that she had only one theory class on tables without handouts and examples to work out! What dive certification course is she taking?
I went through a basic BSAC diving course which lasted 3 months, comprising 6 theory lessons and written exams, 6 swim pool dives using tables, and 6 open-water dives, also using tables. Before a each dive, my buddy and I had to manual calculations in front of the instructor. When we jumped into the water, the instructor followed right behind and stayed with us throughout the dive. When we were back on shore, we had to give him or her a full briefing of what we had done (rightly or wrongly), followed by a lengthy cross-examination. The course was very stressful (with an instructor constantly at my back) but we learnt everything thoroughly, from snorkelling to emergency rescue and even CPR.
For BSAC, diving is the easiest thing to learn; the stress during training is on deco, underwater navigation, emergency rescue, first-aid and CPR. No one can be certified as a recreational diver unless he was able to save another diver’s life.
I agree with the posts, I have been a recreational diver for over 20 years, whilst I was taught using the old tables, the newer computers seem to be the ‘new age’. As a responsible diver you should be able to use the table, it is the foundations of diving, no different than loading an aircraft- you need to know how to work the maths in case the batteries in the calculator fail. – Something here. New technoligies- but need to know/understand the basics. If the dive industry is keeping up with new age- then the computer module should be apart of the Basic Open Water Training – as to the use of the table.
YOU CAN’T USE TECHNOLOGY TO COMPENSATE FOR LACK OF TRAINING. JUST LIKE YOU SEE THESE DIVERS WITH ALL OF THEIR FANCY COLOR-COORDINATED GEAR AND HIGH-TECH EQUIPMENT, BUT ARE STUMBLING ALL OVER THE BOAT. ON THE CONVERSE, YOU SEE THAT GUY WITH THE MASK WITH THE STAINLESS STEEL RIM(BELONGS IN THE SMITHSONIAN INST.), AND HE KNOWS HIS GAME. HE FOLLOWS THE DIVE TABLES AND PLANS HIS DIVE. I LIKE TECHNOLOGY, SUCH AS THE APLLE MAC AND IPOD, BUT I FEEL THE OLD FASHIONED WAY WITH DIVE TABLES IS THE WAY TO GO. MOST PLACES I DIVE, I GUESS TO DECREASE LIABILITY TELL YOU AT THE BRIEFING, “THIS DIVE IS 90 FEET FOR EXACTLY FOR 25 MINUTES”