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10 Rules of Scuba Diving Cheat Sheet by

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Introd­uction

Recrea­tional diving is still a relatively young sport. Created in the 1950s, it gained acceptance in the '60s and '70s, boomed in the '80s and took great techno­logical leaps in the '90s. If you've been diving for decades, there's a good chance that not everything you learned in your open-water class still applies. New research and equipment have made diving safer and more enjoyable than ever—if you know the rules. Let's look at some of them and see how they've evolved.

1. Reverse Dive Profiles Are OK

It is permis­sible to dive deeper on your second dive than on your first, and to dive deeper on the later part of a dive than on the early part.
Dive comput­ers: Because computers can track your depth and time constantly and are pretty good at math, it's possible to know your nitrogen exposure accurately regardless of your profile. Tables, by contrast, can account for only your greatest depth, and this crude approx­imation of nitrogen exposure still mandates a conser­vative approach.
Exceptions to the Rule: Obviously, divers using only tables must still follow the old rules. And even when using a computer, it's still smart to dive deeper first. Ascending profiles give you more bottom time and a greater margin of safety against DCS.

2. Lower Minimum Age

The Recrea­tional Scuba Training Council, which sets many industry standards, dropped its minimum age requir­ement for junior certif­ication near the end of 1999. As a result, PADI, SDI, SSI and NASDS (which has since merged with SSI) dropped their minimum age requir­ements for junior certif­ication to 10. Ten-ye­ar-olds can get a PADI Junior Scuba Diver, and 8-year­-olds can enjoy PADI's Bubble­maker and Seal Team programs, which are held in a pool in less than 6 feet of water. SSI has a pool-only "­Scuba Ranger­" program for 8- to 12-yea­r-olds.
Reason for the Change:
To promote the sport. Lots of divers have kids, and the growing popularity of resort diving meant a market for family dive vacations. "The future of diving will be determined by kids," says Bret Gilliam, president of SDI, the first agency to lower the age. "It's a great step forward to recognize the family unit as key to our sport's growth."
Exceptions to the Rule: It's still up to the instructor to decide whether a child is mature enough to dive. Being 10 does not create a right to be certified.

3. Universal Referrals

Getting certified? Beginning in 1998, you can take classroom and pool sessions in your hometown from an instructor with Agency "­A," then fly to warm water for open-water sessions under an instructor with Agency "­B"— as long as the agencies had agreements to recognize each other's standards and instru­ctors.
Customer conven­ien­ce: Smaller agencies with few instru­ctors in place at resorts found it necessary to band together to offer greater options — especially when certif­ication standards are virtually identical.
Exceptions to the Rule: It can be a matter of trust. Some students may not be comfor­table "­swi­tch­ing­" instru­ctors, and so may prefer making their open-water checkout dives with the same instructor who was with them the first time they took their first breath underwater in a pool.
 

Scuba

4. Slower Ascent Rate

Ascend no faster than 30 feet per minute — one foot every two seconds.
Research has proven: Navy studies found that a 30-foo­t-p­er-­minute rate resulted in fewer cases of DCS than the older 60-foo­t-p­er-­minute rate. A slow ascent is really a rolling decomp­ression stop, allowing your body to flush out and exhale dissolved nitrogen before it forms bubbles.
Exceptions to the Rule: The 30-foo­t-p­er-­minute rate may not always be practical for the whole ascent, especially when you are deep and low on air or approa­ching hypoth­ermia. In that case a faster rate, up to 60 feet per minute, is accept­able, but for the final 60 feet of your ascent, you should slow to 30 feet per minute.

5. The Safety Stop

Make a safety stop at the end of dives. That means you should pause at about 15 feet for a minimum of three to five minutes before your final ascent to the surface. Some experts recommend safety stops as long as 10 to 15 minutes under certain condit­ions.
More resear­ch. The new rule recognizes that all dives are decomp­ression dives, and that DCS can and does occur even when you've stayed within so-called "­no-­dec­omp­ression limits." Studies clearly show that pausing at about 15 feet allows you to offgas nitrogen before ascending through the zone of greatest pressure change, near the surface. Nitrogen that hasn't been eliminated can bubble out of tissues rapidly during the last part of the ascent, causing DCS.
The air in your BC and the bubbles in your wetsuit also expand rapidly during the last 15 feet and may cause you to become signif­icantly positive without realizing it. Stopping gives you a chance to adjust your buoyancy so you don't lose control of your ascent.
Safety stops also allow you to survey surface conditions and boat traffic before surfacing.
Exceptions to the Rule: You needn't stay at exactly 15 feet, especially if you're elbowing a crowd of other divers. Anywhere between 10 and 20 feet is fine. And although three to five minutes is a good minimum, longer, deeper dives call for longer safety stops.

6. Neutrally Buoyant Ascents

Become neutrally buoyant before beginning your ascent and maintain neutral buoyancy throug­hout.
Research reveal­ed: The strain of finning hard while ascending sometimes causes divers to hold their breath. Also, it can lead to air trapping in the lungs. Both present embolism risks. The change also reflects greater confidence in modern BCs, partic­ularly their dump valves. The old rule was designed to prevent runaway ascents.
Exce­ptions to the Rule: In an ascent from very shallow depths, say 30 feet or less, it's OK to fin up against slight negative buoyancy. The risk of losing control because of rapid buoyancy changes in your BC and exposure suit, and the low stress in finning such a short distance, makes this the better bet.

7. No More Buddy Breathing

In a no-air emergency, depend on a redundant system or your buddy's octopus, or make an indepe­ndent emergency ascent. Do not attempt to "­buddy breath­e" from a single regulator unless you and your buddy have practiced it.
Reason for the Change: Safety. Experience showed that unless both buddies had practiced buddy breathing and were skilled at it, the attempt was likely to injure both divers, not just one.
Typically, buddy breathing divers become so absorbed in passing the regulator that they neglect to control their buoyancy, and a too-rapid ascent with embolism could result. Or the diver who has passed the regulator holds his breath instead of exhaling slowly, also an embolism risk.
If you are out of air and neither you nor your buddy has a backup system, your best move is to make an emergency swimming ascent: swimming to the surface while keeping your throat open by slowly exhaling.

8. The Buddy System

Every training agency is emphatic on the need to always dive with a buddy. Yet solo diving has long been common, partic­ularly among underwater photog­rap­hers. Experi­ence, and incomplete statis­tics, don't indicate that solo diving is more dangerous than buddy diving, and some divers argue that solo diving is actually safer.

9. The Snorkel

Most of us were taught that a snorkel is mandatory gear on every dive, just like a pair of fins. But increa­singly, divers are leaving the snorkel in the gear bag much of the time.
Why? They've come to the conclusion that a snorkel, when attached to your mask, is more often a hazard than a help. The long tube—d­angling from its midpoint so the hook-like gizmos at the ends can wander around — is pretty effective at catching kelp, fishing line and camera straps. And, given the importance of your mask, your mask strap is about the worst place to mount it or anything else.
Many divers now save the snorkel for special occasions, like a long surface swim from their entry point to the dive site, and carry it in a pocket or strapped to their body.

10. The Dive Computer

The dive computer is probably the most important safety advance in the sport. Much more important than a snorkel, and arguably more important than an octopus, a dive computer should be considered mandatory equipment today. "­Vir­tually all divers now use dive computers to make diving safer and more enjoyable.

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