Most rebreather divers can recite the unit check from memory. Loop holds positive, sensors track linear, scrubber packed and dated, bailout on and turned on. Then the boat leaves.
Ask that same diver who they’d call from the boat if somebody surfaced unresponsive, and the answer usually goes quiet. The other half of a dive safety checklist has nothing to do with the machine. It’s the phone numbers, the emergency oxygen, the people on deck who know what a loop is, and a drill somebody has run at least once. That half is normally unwritten.
What Belongs on a Safety Checklist Beyond the Unit?
Four things. A current list of emergency numbers for the water you’re diving. Enough surface oxygen to cover the run to help. A crew briefed on what a rebreather casualty looks like. And a plan somebody has practiced out loud. The unit check proves the machine works. This proves the rest of the day does.
None of it’s expensive. Most of it is a conversation and a saved contact card. It gets skipped because it belongs to nobody in particular, and a list without an owner doesn’t get run.
So give it an owner. On a private boat that’s whoever organized the dive. On a charter it’s worth asking rather than assuming, because the answer varies more than divers expect.
The Numbers Somebody Has to Have Before You Splash
Commercial diving doesn’t leave this to memory. The US federal rule on pre-dive procedures is blunt about it. A list shall be kept at the dive location of the telephone or call numbers of the following: an operational decompression chamber, accessible hospitals, available physicians, a means of transport, and the nearest Coast Guard rescue coordination center.
That rule governs commercial operations. It doesn’t bind a sport or technical diver on a weekend charter. But the list doesn’t change just because the obligation does. Those are the same five things you’d be scrambling for at the worst possible moment.
Write them down before the trip. A note on your phone is fine. A laminated card in the dry box is better, because phones get wet and batteries die.
The list goes stale faster than you think
Chambers close. Some run daylight hours only. Others take referrals through a hospital rather than direct calls, and a few operate seasonally.
A number you copied from a forum post two seasons ago isn’t a plan. Confirm the chamber nearest your dive site is staffed and taking divers during the window you’ll be in the water. That one call is the highest-value thing on this page.
Who on the Boat Knows You’re Diving a Loop?
Often nobody. Crew briefings get built around open-circuit divers, so the signals the deck watches for are the wrong ones. A rebreather diver in trouble may surface without ever having touched a bailout regulator, and the cylinders on their back can still read close to full. Say what you’re diving before you gear up.
It matters in the water too. An open-circuit buddy tracks you by your bubbles, and on a loop there aren’t any to track.
Tell the crew three specifics. What you’re diving, how long you plan to be down, and where your bailout sits. That last one changes the answer if a recall goes out, because a diver whose bailout is slung off-board has a different problem from one carrying it on the unit.
Surface Oxygen Isn’t the Oxygen on Your Back
Divers conflate these constantly. The oxygen cylinder feeding your loop is plumbed into a life-support circuit and sized around the dive you planned. It isn’t a treatment supply, and it isn’t reachable by somebody working on a casualty on deck.
Surface oxygen is a separate kit with its own mask, its own regulator and its own duration. Whether the boat carries one, and whether anybody aboard has been shown how to use it, is a question with a real answer. Ask it on the dock.
If you can’t confirm what’s aboard, treat that as a gap to close rather than a detail to assume. That’s the same discipline we apply to specs and compatibility questions on the equipment side. When something can’t be verified against the manufacturer documentation, the honest move is to go and check it, not to fill the space with something plausible.
How Far Are You From Help You’d Actually Use?
Measure it in hours, not miles. What counts is the time between a diver surfacing and a chamber that’s staffed and willing to take them. Near a major port that can be short. On a remote itinerary it stretches, sometimes into days, and that should change how conservative the plan is long before anything goes wrong.
Distance also decides what’s worth carrying. Spares you’d never pack for a local shore dive earn their place once a failed unit means a lost week rather than a lost afternoon.
Divers heading out on trips to genuinely remote reefs tend to plan this well, because the isolation is obvious. The riskier profile is the familiar site two hours from home, where nobody thinks to ask and everyone assumes somebody else has.
Your dealer is a useful second opinion here. Silent Diving routes buyers to a dealer for hands-on support rather than selling a unit off a page, and the dealer network runs across the United States, Canada, Latin America and the Caribbean. Somebody in it has dived where you’re going. Talk to an AP Diving dealer before your next trip and ask what they carry for that trip.
A Plan You Haven’t Rehearsed Is Just a Document
This is where most plans quietly fail. Divers Alert Network makes the point directly in its emergency planning series. An EAP is only as good as the practice it receives. An EAP is an emergency action plan, and the practice is the part everybody skips.
Rehearsal doesn’t need to be elaborate. Walk it through on the surface interval. Who calls, on what phone, with what number. Who runs the oxygen. Who writes down the times.
Times matter more than divers realize. A treating physician will want the depth profile, the setpoint history and the ascent. Much of that already sits in your unit, and the download you review after a normal dive is the same download that becomes evidence after a bad one. Knowing how to pull it under pressure is worth practicing while nothing’s wrong.
Run the drill once a season. It takes ten minutes and it’ll expose a gap you didn’t know you had.
Frequently Asked Questions About Dive Emergency Planning
Do recreational divers need a written emergency action plan?
No rule requires one for sport diving. The federal pre-dive standard that mandates an emergency contact list applies to commercial operations. Recreational and technical divers sit outside it. That doesn’t make the plan less useful, and writing one costs an evening.
How often should a dive team practice its emergency plan?
Often enough that nobody has to think about their role. Once a season suits most private groups. Teams with rotating members need it more often, because the person who missed the last run-through is the one who’ll hesitate. Short and regular beats long and annual.
Can the oxygen on a rebreather be used for first aid?
Treat it as unavailable. That cylinder is plumbed into a life-support circuit and isn’t configured to deliver oxygen to an injured person on deck. Surface oxygen is a separate kit with its own mask and regulator. Confirm the boat carries one before you dive rather than after.
What makes a rebreather emergency different on the surface?
The usual signals are missing. There are no bubbles to watch, gauges can still read full, and a diver may have surfaced without touching bailout. Crews trained on open circuit may read the scene as fine. Telling them what you’re diving is the cheapest fix available.
Who should hold the emergency contact list on a dive boat?
One named person, agreed before departure. Shared responsibility becomes nobody’s responsibility once something happens. On a charter that’s usually crew, though it’s worth confirming rather than assuming. On a private boat, name whoever organized the dive and put a copy in the dry box.
Does a longer dive change the emergency plan?
Yes, in two ways. A decompression obligation removes the option of surfacing immediately, so the surface response starts later than anybody wants. Longer runtimes also mean the boat waits longer before a missed check-in looks wrong. Agree a hard overdue time before you get in.
Your Next Step Before the Next Trip
Pick the next dive on your calendar. Find the chamber that serves it, call to confirm it’s open and taking divers, and save the number somewhere that survives a wet phone. That’s twenty minutes of work, and it’s the single largest gap in most otherwise careful dive plans.
Then handle the equipment side of the same question. Bailout volume, spares and the consumables that decide your usable bottom time all shift once help is further away.
Those aren’t decisions to make alone at a kitchen table. Talk to an AP Diving dealer before your next trip and go through the trip before you book it.