Shutdown Drillby Mark Barakat-Brown Start
Inside a wreck's cargo hold, a buddy reaches for the manifold on a diver's twinset

Manifolded doubles trainer by Mark Barakat-Brown

Know the shutdown before you need it.

Spring a failure on a virtual twinset, find it, and shut the valve that actually stops it. On your phone, as often as you like.

Start the trainer How it works

A free-flowing regulator on a twinset dumps gas fast. The fix sits behind your head, out of sight, done by feel, in gloves, and you only get to practise it in the water. Shutdown Drill lets you rehearse it anywhere.

Two modes
Free play and TrainingSpring any failure yourself, or take a scored run of five random ones.
Runs anywhere
In your browserPhone, tablet or desktop. Nothing to install.
Price
FreeNo account, no sign-up.

Inside the rig

  1. 01 / 07

    Two cylinders.

    A twinset starts as two 12 litre steel cylinders, banded together. On their own they can't share a single breath.

  2. 02 / 07

    One manifold.

    A valve body screws into each neck and a crossbar joins them. Now the pair behaves as one 24 litre supply.

  3. 03 / 07

    Three valves.

    A post valve on each side, and an isolator in the middle that can split the set back into two.

  4. 04 / 07

    Two first stages.

    Long hose and wing inflator on the right post. Backup and pressure gauge on the left.

  5. 05 / 07

    Charged.

    200 bar in each cylinder. 4,800 litres of gas, all of it reachable through either post.

  6. 06 / 07

    Then something lets go.

    A free-flowing regulator dumps gas fast, and the fix is behind your head, out of sight.

  7. 07 / 07

    Shut the valve that stops it.

    Right post closed. The long hose goes quiet, the backup still breathes, and both cylinders are still in reach.

    Practise it in the trainer
200 BAR 200 BAR LONG HOSE INFLATOR BACKUP SPG LEFT POST ISOLATOR RIGHT POST

Try it

Three valves. Three different jobs.

Tap the knobs to see where your gas can go.

Backup Long hose Left cylinder Right cylinder Reachable Reachable Left post Isolator Right post

Seen from behind, the way your buddy sees it.

Regulators
Long hoseRight postAll your gas
BackupLeft postAll your gas

Everything open. Both regulators reach all of your gas.

What each valve shuts off
Right postLong hose and wing inflator. Stops anything downstream of the right first stage.
Left postBackup, SPG and drysuit hose. Stops anything downstream of the left first stage.
IsolatorThe link between the cylinders. The only valve that can protect you from a neck, burst disc or crossbar leak.

Standard backmount hose routing. The order you practise the drill in is your agency's call, not ours.

The trainer

Find it. Shut it.

A failure goes off somewhere on the rig. Read the bubbles, the gauge and what stops working, then shut the valve that actually stops it. Play freely, or switch to Training for a scored run of five.

Cutaway trainer
Cutaway trainer
Loading the trainer…

Twin 12s at 232 bar, standard backmount hose routing. A briefing and dry-run aid, not a substitute for in-water training with an instructor.

Mark in a twinset, torch in hand, beside a ship's coral-covered propeller

Then do it for real

Take it underwater.

The trainer builds the habit. A doubles course with a qualified instructor builds the diver. Learn backmount doubles with Oyster Diving.

Train with Oyster Diving
Mark Barakat-Brown · Oyster Diving

Who's behind it

Made by Mark Barakat-Brown at Oyster Diving.

Mark is Oyster Diving's Head Tec Instructor. Oyster Diving is a UK dive school, dive shop and dive travel company. The trainer is free.

Endorsed by Paul Toomer, PADI Global Technical Diving Consultant.

  • Dive coursesFrom your first breaths underwater to technical training, including backmount doubles.
  • Dive holidaysDiving trips abroad, planned by divers.
  • Dive shop and servicingKit to buy online, with advice from people who dive it, and servicing for the kit you already own.
Visit oysterdiving.com

FAQ

Questions.

What is a valve drill?

A valve drill, also called a shutdown drill, is practising closing and reopening the valves on a manifolded twinset so you can stop a failing regulator or a leaking manifold while keeping as much gas as possible within reach.

Does it teach a particular agency's drill?

No. Agencies teach different drill orders and procedures. Shutdown Drill shows you what each valve shuts off and which valve actually stops each failure. Practise the order your instructor teaches.

Does this replace training?

No. Shutdown Drill builds understanding and quick recognition on land. Learn the drill, and practise it in the water, with a qualified instructor, and follow the procedures your training agency teaches.

Which setup does it model?

Backmount doubles on an isolation manifold, with the long hose on the right post and the backup regulator on the left post. That's the most common configuration taught for technical diving.

Does it work on my phone?

Yes. The trainer runs in any modern browser on a phone, tablet or computer. There's nothing to install and no account to create.

Is it free?

Yes. The trainer is free, including the scored training runs.