Confined Water Skills 2 — Emergency Procedures and Air Management

Why Emergency Procedures Matter in Aquaculture Diving

Aquaculture and marine science divers work in net pens, under docks, and around submerged structures where visibility can be poor and exit paths are not always direct. Running low on air or losing your buddy's location in those environments is a realistic hazard, not just a training scenario. Mastering out-of-air procedures and air management before you ever enter open water is what separates a safe commercial diver from a statistic.

Out-of-Air Scenarios and the Octopus Regulator

Every scuba unit used in this program is equipped with an octopus — a second second-stage regulator on a longer hose, usually marked with a bright color (yellow is common) so it can be found quickly under stress. When a diver signals out-of-air (a hand drawn across the throat), the buddy's job is to immediately locate the octopus and present it mouthpiece-first to the distressed diver. The distressed diver takes it, purges if needed, and begins breathing. Both divers then grip each other — wrist-to-wrist or a secure arm hold — and begin a slow, controlled ascent together.

PADI standards require an ascent rate of no faster than approximately 9 meters (30 feet) per minute for recreational depths. Ascending faster than this increases the risk of decompression sickness (DCS) even from shallow depths. In confined water practice you will use a depth gauge or dive computer and a stopwatch to verify your rate. The donor diver controls the ascent while continuing to breathe normally from their primary regulator.

Key steps for octopus donation:

1. Out-of-air signal received — locate your octopus immediately.

2. Present the octopus mouthpiece-first to your buddy.

3. Allow the distressed diver to secure the regulator and establish breathing.

4. Establish a secure hold on each other.

5. Signal OK, then begin a controlled two-person ascent at approximately 9 m per minute.

6. Maintain eye contact throughout. Do not release your buddy until both are at the surface.

Controlled Emergency Swimming Ascent (CESA)

If your buddy is not within reach, a CESA is your backup. The CESA is used when a diver runs out of air and cannot reach a buddy or alternate air source in time to complete a normal ascent. It is practiced from the bottom of the pool (up to 9 m depth in confined water training).

The single most important rule of CESA: never hold your breath. As you ascend, the air in your lungs expands because water pressure decreases. Holding that expanding air causes pulmonary barotrauma — a burst lung — which is life-threatening. Instead, exhale continuously in a slow, controlled stream throughout the entire ascent. You will be surprised how long that air lasts when released gradually.

CESA procedure:

1. Recognize the out-of-air situation.

2. Look up and reach up toward the surface.

3. Kick smoothly upward — no frantic kicking.

4. Exhale continuously from the moment you leave the bottom. Make a steady "ahhh" sound if it helps you remember to keep exhaling.

5. Maintain an ascent rate that does not exceed approximately 9 m per minute. In a 9 m pool, that means at least one minute of controlled ascent.

6. Do not stop or level off — maintain steady upward movement.

7. Upon surfacing, inflate your BCD or drop weights if needed and signal for assistance.

Air Management and Surface Air Consumption Rate

Running out of air is almost always a planning failure, not a random event. Aquaculture dive plans require you to know your Surface Air Consumption (SAC) rate — how much air (in bar or psi per minute) you breathe at the surface. Once you know your SAC rate, you can predict how long a cylinder will last at any depth.

Pressure group and reserve rules: Always surface with a minimum reserve as specified in your dive plan. A common industry practice is to reserve at least 50 bar (approximately 500 psi) for safety, but your dive supervisor will set the specific minimum for each job. In today's lab your instructor will set a stated minimum — you must track your SPG throughout the exercise and surface with that reserve intact.

During the air management exercise, record your starting pressure and the time at depth on your underwater slate. After the dive, calculate your SAC rate using the formula shown in the worked examples below. Knowing your personal SAC rate lets you plan future dives accurately and prevents the out-of-air situations you practiced escaping from today.

Safety Rules for This Lab

• Never dive alone. Buddy pairs stay together at all times. The instructor or a designated safety diver observes from the pool deck or in the water.
• No breath-holding drills of any kind except CESA, and during CESA you are exhaling, not holding.
• If you feel panic, give the out-of-air signal or thumbs-up (abort dive) signal immediately — there is no shame in surfacing.
• Check your octopus location and SPG reading before every entry.
• Loose equipment can snag on net pen infrastructure; keep all hoses tucked and streamlined.
• Follow lockout/tagout procedures for any poolside mechanical equipment (pumps, filtration) before entering the water. Verify the pool's electrical bonding is intact with the instructor before the session begins.
• Wear all required PPE: wetsuit or exposure suit appropriate to water temperature, mask, fins, BCD, weight system, and SPG-equipped regulator with octopus.