Open Circuit Rules for Technical Diving

In 2001 Andy Holman and I were working to launch a technical diving club in Southern California.  It did not really go anywhere.  But, part of our efforts was to come up with some resources to help members and the general public to be better divers.

I recently came across our efforts.  This was part of our work.  Most of it is still very valid. Some of the comments on deep stops may or may not be valid any more.  There is mounting evidence that certain applications of deep stops may not be best practice.

See what you think.  Anything you would add?

Anything that should be removed?

Rebreather Rules can be found here.

Open Circuit Rules of Survival  (OCRS)

Draft Version 1.2

1.      Equipment

Maintain and prepare equipment a few days before the dive day.

Don’t dive if equipment is not 100%.

Be willing to call the dive or dive trip.

Dive a standardize kit.

Ideally, the team should dive the same configuration.

Master one system for equipment first. Better to be good one way than crappy at a lot.

Equipment survey classes do not work.

Rig for wreck diving and dive with cave technique.

Learn how to adopt new configurations, if necessary.

Integrate configuration changes slowly.  Walk them up from the pool.

Use the most appropriate configuration for the planned mission of the dive.

Be multi-environment and multi-mode capable if your diving requires it.

NEVER dive a configuration without proper training in that configuration or mode or environment of diving.

Always plan for failure at worst point in the dive (depth, distance, time).

Be willing to call the dive at any point if safety is in question.

Always conduct predive checks.

Checklists are a good thing.

You should never dive if equipment is an issue.

Only use the best equipment possible.

Equipment should not be your limiting factor.

Carry only what is necessary for the dive and safety.

Streamline your kit for a balanced and hydrodynamic profile.

It is better to be good with your skills than to dive deep with bad skills.

Equipment handling and dive operations should be second nature.

Technical diving is more than equipment management.

Over-learn skills.  Responses should be automatic.

You should feel completely comfortable accomplishing something on the bottom phase of the dive.  If not, go back to the pool.

If you are amazed that you made it back from a dive, STOP technical diving.  Perhaps you should take up golf?

If you are not good with liftbags, learn how to use them.

Buoyancy control is critical for sport diving, I would bet it matters more here.

When diving wet, you must have a redundant BCD.

When diving dry, if you cannot swim without any air in your BCD at the beginning of a dive, your drysuit will not help you.  Have a redundant BCD.

Your kit should have sufficient redundancy to not have equipment keep you from coming back from a dive.  However, anything that is unnecessary should be removed.  Anything that is not standard must be justified.

All hoses are routed down and in.

One is none and two is one.

Always have a redundant gas supply.

If you are technical diving, doubles with an isolator manifold is mandatory.  Or use sidemount.

Independent doubles are unacceptable.

Always have enough gas to comfortably ascend while making all required safety and decompression stops.

2.       Predive Planning

Make sure all variables are accounted for before entering the water.

Complete accounting of oxygen, decompression, inert gasses, gas management, thermal exposure, mission and logistics must be known for each diver in the team.  If there is a number, you do not know for sure till you have one.

These are the planing questions that should be answered in each area.


What is the planned maximum PO2 for the dive?

What is the CNS and Pulmonary exposure?

Is there a better choice for maximum PO2?

What is the maximum PO2 that is acceptable for decompression?

How do I plan to avoid Hyperoxia?

How do I plan to prevent Hypoxia?

Do you have enough room in CNS time to extend the profile?

Have I accounted for repetitive dives and/or repetitive days?

Have I visualized my gas switches?

Do I have a system for gas switching?

Are my cylinders properly marked?

Are my cylinders analyzed?

Do I have a system to cover a bad gas switch?

Do I carry my deco gas with me or can I stage it?

What schedule do I plan for oxygen breaks?

Is this schedule often enough? Or too often?

Do I plan on making back gas breaks before a gas switch?


What system will I use to safely control decompression on the dive? (EAD, Air Computer, Nitrox Computer, Multi-gas computer, or Custom table)

What decompression obligation am I able to handle?

Am I qualified, willing, prepared, and able to do this level of decompression?

What if I over stay my bottom time?

What if I exceed my planned depth?

What contingency tables or backup do I use?

How do I plan on accomplishing decompression?

What method do I plan to use to communicate with the surface?

Where will I conduct decompression?

Have I properly padded my deep stops?

What if I have to bailout from the dive early?

Am I accelerating my deco?

What if I get bent?

Do I have sufficient oxygen for the dive and post dive?

Can I perform surface decompression?

What rate do I plan to ascend during the dive?

Can I slow down my ascent to the surface?

Can I rest at the surface?

Can I remain on oxygen at the surface?

Are my buoyancy skills good enough to conduct deco in blue water with no reference?

What algorithm do I plan to use for calculating the dive profile?

Is everyone comfortable with the profile?

How will I handle the loss of a deco gas?

How will I abort the dive early?

Can this be made easier?

Inert Gasses:

What level of narcosis have I planned for?

Am I comfortable with that level of narcosis?

Am I considering oxygen as narcotic?

Have I accounted for my CO2 production?

How do I plan to minimize CO2 issues?

Are there mission considerations that would require a different choice of gas in regard to narcosis?

Am I diving in an overhead (wreck, cave, or ice) environment?

Am I accustomed to this environment?

Is it darker, deeper, or scarier than I have experienced?

Gas Management:

Do I have enough oxygen to complete the dive?

Have I accounted for the proper reserves?

Do I have enough back gas?

Are my gas choices the best for the mission?

What intermediate gasses do I want?

Can I carry all the gas I need with proper reserves?

Should I shorten the dive to allow for more reserve?

Can I maintain the breathing parameter necessary to conduct this dive as planned?

Do I really understand that gas is time at depth?

Do I have sufficient gas if I exceed my depth or over stay my planned time?

Do I need dedicated support?

How will I inflate my drysuit?

What is my gas management plan and is it appropriate?


 Am I properly insulated to complete the entire dive in relative comfort? (Losing heat can be as deadly as losing gas or not completing deco.)

Is a wetsuit proper for this exposure?

How will I supply gas to my drysuit?

Do I need argon?

How will I supply argon to my suit?

What is the bottom temperature?

What is the temperature I will be decompressing in?

Do I have the thermal tolerance to complete this dive?

Have I planned for repetitive dives?

How will I rewarm after the dive?

Will I continue to lose heat after the dive?

Is there a better choice for insulation?

Should I shorten the dive to account for heat loss?

Have I dived in this temperature before?

Do I remember that the water is always colder than I think?


Is this dive worth doing?

Should I be doing this dive?

What is the plan for the bottom?

Am I prepared for the bottom activity?

Do I have the necessary tools to be successful on the bottom?

Do I have the necessary skills and experience to do this dive with confidence?

Who is my team?

Am I comfortable with my team?

Does this dive require surface rehearsal?

Does this dive require dedicated surface support?

How am I being deployed on the dive?

How am I descending on the dive?

What is my priority list for the bottom?

What is my runtime for this dive?

When do I need to be off the bottom?

How am I ascending from the bottom?

How will I complete deco safely?

How will I communicate with the surface?

Do my support divers know how, when, and where to reach me?

Do I need to plan for any special procedures during deco?

How do I plan to handle gas switches?

How do I plan to communicate with my teammates?

Do I remember that deco is the longest part of the dive?

Do I remember that the dive is not over when I start deco and it is just beginning?

How will I handle the loss of a gas?

How do I plan to abort this dive?

How can this fail?


Do I have the resources to do this dive?

Do I have all the gasses I need to do all my diving?

Do I have the platform necessary to be successful on this dive?

Do I have sufficient support for this dive?

Do I feel comfortable with everyone who will be on this dive?

Do I have all the components necessary to conduct all the diving for all the days planned?

3.       Drills while diving

Conduct gas, depth, and time checks on all dives.

Always check lights, leaks, thirds, and valves on the surface.

Always conduct an S drill when diving with a new partner.

Always conduct a modified S drill on all dives.

Ensure that you are able to maintain depth at the end of the dive with minimal gas and no stages or with stages if stages are buoyant.

Be aware of unexpected buoyancy changes or noise.

Practice valve shut downs often.

Valves all open on back gas.  Stages are charged and off.

When conducting gas switches, always purge the second stage prior to attempting to breathe from it.

Always use anti-silting techniques.

Maintain a balanced and hydrodynamic profile at all times.

Communicate with your partner at all standardized times and as needed.

Remember your role as a backup brain.  Do not let yours go on vacation.

Anyone can call any dive for any reason with zero consequences.

4.       Avoid Stress

Avoid rushing into the water or rushing to put equipment on.

Time pressure will kill you!

There is always time for a buddy check, bubble check.

Avoid equipment loading, buddy pressure.

Choose a patient buddy.

5.       Are you solo diving?

Watch your buddy to make sure your buddy is watching you.

Test your buddy (If you can count to 200 between buddy eye contacts your buddy will not save you).

Don’t solo dive.  Your qualified buddy is the last chance to save you.

If you solo dive, be cautious, dive shallower than usual for less time and under more ideal conditions.

The only time you and your buddy are safe is on the boat sitting down or on land out of the water.

Use constant and consistent communications throughout the dive.

Carry extra gas.  Gas is time underwater.

If you run out of gas and it is not due to equipment failure, IT SUCKS TO BE YOU!  Your buddy’s reserve is not for you.  It is his.  He can choose to give it to you, but it is not yours’. Do not treat it like it is, plan accordingly.

There is no backup brain!

6.       Complacency

Watch for over confidence. Are you really ready for the dive?

There are old tech divers and there are bold tech divers.  There are very few old and bold tech divers.

Work up to depth slowly; baby steps will save your life.

Never let your brain talk your ass into something it cannot get you out of.

If you suck, you should know it at this level.  Get better training.

Keep training until you are totally confident in your skills.

You are never totally confident in your skills.

You are never done.  Get over it already.

You are not as good as you think you are.  No one is.

Progressive penetration is bullshit.

Other Rules

  1. After you clear your 15-fsw stop ascend slowly to the surface.  The dive is not over till over a half an hour has gone by on the surface.
  2. After you clear your 15-fsw stop ascend slowly to the surface.  The dive is not over till over a half an hour has gone by on the surface.
  3. Breathe oxygen at the surface with minimal movement for at least ten minutes after a dive, if possible.
  4. Have a portable chamber on the boat if you are 220+ miles from shore.
  5. Think carefully about when and how you switch off helium mixtures.  It might be better to keep some helium in your mixes until on oxygen.  Oxygen is your friend.
  6. Always analyze all of your gasses immediately before diving.  Label them appropriately.  Never breathe any gas unless you are absolutely certain what it is.  Have a system for gas switches, visualize them, and double check your buddy after every switch.  Monitor yourself and your buddy for signs of hyperoxia.
  7. Have necessary backups on the boat with you.  Support divers should be able to solve most problems.  Make sure your plans deal with proper logistics for support divers if they are needed.  There are no dive shops at sea.
  8. Dives below 250 feet (75M) should not be conducted if unsupported.  If the exposures are long on shallower dives, they should be supported as well.
  9. In open water operations, it is better to conduct multiple dives to depth rather than one long exposure.  The uncertain conditions in the ocean expose the diver to too much risk if decompression obligations are long.
  10. Only you can control your dive.  The only mission that matters on any dive is that all return safely.  Nothing is worth dying for on a dive, including someone else.
  11. If you are going to pad your decompression do it deep, the benefits out weigh padding stops in shallow water.  Skew decompression to deeper stops.  Be slow to get off the bottom; do not rush to get shallow.  Plan accordingly.  Deep stops are more important than shallow stops.  All stops are important.
  12. Plan the dive and actually dive the plan.  The devil is in the details. Execution is more important than accomplishment.  It is not what you do, but how well you do it.
  13. Utilize precision diving techniques and skills.  Always try to be better tomorrow than you were today, better the next dive than this one, and better on this dive than the last one.
  14. Strive to know every aspect of any dive you go on.  If there is a number, have it.  If there is a concern, answer it.  If there is a doubt, don’t dive with it.  Know where you are and all aspects of the dive at all time.  Develop super awareness to all components and activities of the dive.  You will see things before they are issues and take steps to fix them before you would have even noticed them in the past.

Conclusion: If you cannot or will not accept the risks, costs, physical demands, training requirements, and/or mental demands that technical diving requires, you should not attempt it.  There are plenty of great adventures to be had in shallow waters.  Just diving deep or going into required stops on your computer is not technical diving.  It is just stupid.  Technical diving is an adoption of a mindset, approach, and attitude as much as it is diving with the gear or taking training.  If you choose to do this, do it well.  Keep training and never dive unless you know you will be successful.  Your life is always the most important one.

One Comment on “Open Circuit Rules for Technical Diving”

  1. […] Open Circuit Rules for Technical Diving […]

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