How to Read and Use a Dive Table Safely
Dive tables are a crucial backup and learning tool that help divers understand how to manage nitrogen exposure and stay within safe limits.
SAFETY WHILE DIVING
How to Read and Use a Dive Table Safely
Before dive computers became common, dive tables were the essential tool for planning safe dives. While many divers now rely on technology, understanding dive tables remains a critical skill—especially as a backup. Whether you're just learning or brushing up, this guide will help you confidently read and use a dive table to plan your dives safely and responsibly.
What Is a Dive Table?
A dive table is a chart that helps divers estimate how long they can stay underwater at a certain depth without needing a decompression stop. It also helps calculate surface intervals and plan repetitive dives by accounting for residual nitrogen in the body. Most recreational divers use the PADI Recreational Dive Planner (RDP) or similar tools from other agencies like SSI and NAUI.
Reading the Dive Table: Step-by-Step
Let’s say you’re using the PADI RDP:
Find Your Depth: Start on the left-hand column to locate your planned depth. Tables typically go from 35 to 140 feet.
Match the Bottom Time: Move across the row to find your planned bottom time. This shows your pressure group at the end of the dive.
Calculate Surface Interval: Use the surface interval table to determine how long you need to wait between dives. This reduces the amount of residual nitrogen.
Plan a Second Dive: Use the pressure group from your first dive and surface interval to determine your new starting group. Then go back to the main table and adjust your bottom time accordingly for a safe repetitive dive.
Why It Matters
Relying solely on dive computers without understanding the basics can lead to risk if your equipment fails. Knowing how to read a dive table ensures you're not just diving safely but also responsibly. It empowers you to make informed decisions and understand the science behind no-decompression limits.
Common Mistakes to Avoid
Rounding Down: Always round up for both depth and time to stay within safe limits.
Ignoring Residual Nitrogen: Don’t skip this step when making repetitive dives.
Surface Interval Miscalculations: Overlooking proper surface time can increase your risk of decompression sickness (DCS).
Failing to Plan: “Winging it” underwater without a clear dive plan is a recipe for problems.
When to Use a Dive Table
Even if you’re diving with a computer, dive tables should be part of your training toolkit. If your computer malfunctions or the battery dies mid-trip, a dive table and waterproof slate could literally save your dive—or your life.
Happy and safe diving,
The ScubaBlast Team
Divers Alert Network. (n.d.). Dive Tables: How and Why to Use Them. Retrieved from https://dan.org/health-medicine/health-resources/dive-safety/diving-fundamentals/dive-tables/
PADI. (n.d.). Using the Recreational Dive Planner (RDP). Retrieved from https://www.padi.com/courses/advanced-open-water-diver
Scuba Diving Earth. (2023). How to use PADI dive tables explained. Retrieved from https://www.scubadivingearth.com/how-to-use-padi-dive-tables-explained/