Introduction: Reading Dive Tables
How to read a PADI Recreational Dive Planner... If you've ever wondered what the hardest part of scuba diving is - this is it. And I'll give you a brief introduction on how to do it.
As it seems quite a few people are into kite boarding (well, admin mostly), I figured I would share some other water related fun considering I live close to some of the top rated dive spots :P Next I'll show you how to make $30 equipment have the same functionality as the $60+ stuff ;)
Step 1: All You Need Is a Your Dive Table and Your Brain.
First, I want to reiterate why nowadays scuba diving is safe and sex is dangerous. A great deal of time and research was put into how diving stresses the human body. Many people risked their lives (and likely a few deaths we have not heard of) to work on this research to make scuba diving safer for the recreational diver.
The reason scuba is considered 'safe' nowadays is a direct result of diver TRAINING in addition to advancements in equipment. Dive shops refuse to fill my father's old tanks due to these advancements. Therefore, DO NOT ATTEMPT WITHOUT PROPER TRAINING AND CERTIFICATION. Hopefully, these instructions will dispel some fears about diving in general and show that almost anyone can do it.
Everything you see in parenthesis () -- is an example dive to follow ;)
Step 2: Side 1 - Table 1 (Left Side)
This table categorizes dive depth and 'bottom time.' Bottom time is considered the time it takes to reach depth + actual bottom time + time to surface. This allows for some margin of error. ALWAYS round up.
Also on this table is:
"Safety Stop Required" (gray boxes) - this means you must stop at 15 feet for 3 minutes before surfacing.
"No Decompression Limits" (black boxes) - if you exceed this time for less than 5 minutes, take a safety stop at 15 feet for 8 minutes, and stay out of the water for at least 6 hours before another dive. If you are there for more than 5 minutes, take a 15 minute (air supply permitting) safety stop at 15 feet and stay out of the water for at least 24 hours. This depth should only be exceeded in case of emergency. Loosing equipment is NOT an emergency. Should you feel any effect of decompression sickness after you surface, seek medical attention ASAP (hyperbaric chamber). This is not something you should just walk off. Plan your dives and this won't happen ;)
"Pressure Group" - Categorized A-Z to make reading the next two tables easier.
Step 1: Select your planned dive depth ('60' feet)
Step 2: Select your planned bottom time ('17' minutes - pressure group 'E')
Step 3: Dive OR Goto Table 2 if you plan to do multiple dives
Step 3: Side 1 - Table 2 (Right Side)
This is the surface Interval Credit Table. If you plan on taking more than 1 dive, this tells you how much 'credit' you have earned. The longer you are under compression breathing compressed air - the more nitrogen saturates your tissues. The longer you are out of these conditions, the more nitrogen is able to safely leave.
Step 4: Select your surface time from the table. ('0:08-0:16')
Step 5: Slide your finger down to bottom of table and read your new pressure group. ('D')
Step 6: See Side 2 - Table 3
Step 4: Side 2 - Table 3
This table is the "Repetitive Dive Timetable." Based on the residual nitrogen levels from the previous dive, this table adjusts your new max bottom time for your next dive.
What you'll see:
"Pressure Group at End of Surface Interval" - the letter you got from Table 2
"Residual Nitrogen Time (RNT)" (white area)
"Adjusted no-decompression time limits"
Step 7: Find your pressure group ('D')
Step 8: Slide your finger across your planned second dive depth row until you hit your pressure group column (let's say 40 feet -- '25/115')
Step 9: Note your new adjusted no decompression limit ('115')
Step 10: Add your RNT ('25') to you're second dive's planned bottom time (lets say 20 minutes). This is now your 'Actual Bottom Time' (ABT - '45').
Step 11: Repeat process as normal from Table 1 using your calculated ABT. At 40 feet, '45' minutes does not exist, so we use '48' feet instead.
Step 5: Other Notes
This table does not apply to dives above 1000ft (say a lake dive).
This table does not apply to rebreathers -- which is really not recreational diving anyway :P
Follow S.A.F.E. Dive - "Slowly Ascend From Every Dive." Ascend no faster than 60 feet per minute (about the speed your bubbles rise)
Should you expect strenuous conditions (cold, current, etc.) - add 10 feet.
Each successive dive should be shallower than the last.
If you plan on flying, wait at base level for at least 12 hours to avoid decompression sickness.
Never EVER hold your breath while breathing compressed air.
Always dive with a buddy, and don't forget to check both octopus-rigs (secondary regulator).
Touch Coral - it dies. It is as simple as that.
There are special circumstances for dives in groups W, X, Y, and Z. Get certified to learn why it is important to know these thing :P
We're always warned: "Since Little is presently known about the philological effects of multiple dives over multiple days, divers are wise to make fewer dives and limit their exposure toward the end of a multiday diver series."
Yes, I have a certification with PADI.
PLAN YOUR DIVES, AND YOU'LL DIVE SAFE.