The following article is edited from an e-mail that appeared on the BTRSAC Newsline. It was originally written by Dave Lock and was prompted by concerns about buddy checks and dive marshalling when Dave was using his ‘new toy’, a Buddy Inspiration rebreather.

It does not describe how a closed circuit rebreather works but is solely concerned with the specific area of buddy checks and information the Dive Marshal is likely to need.

• Components of the System
• Buddy Check
• Dive Marshall Information
• Summary

The backpack contains the gas source, the scrubber unit and two reducing valves, normal first stages. In front of this sits a wing style BC which are used to adjust buoyancy. These are controlled by an autoair or a normal AP200 inflator as many of you have on your stab jackets. The front of the unit looks quite cluttered but is quite comfortable and easy to use. Over each shoulder is a breathing bag with a hose connected to the mouthpiece. There are pressure gauges for diluent and oxygen cylinders plus two controllers which indicate the partial pressure of oxygen in the breathing loop.

The counterlungs form a loop with the diver’s lungs, hence if the mouthpiece drops out in the open position they will collapse and there will be a loss of buoyancy

This should follow the same format as usual - buoyancy, releases, air.

• Buoyancy
  
  The direct feed for the drysuit and the dump valve should be shown and the controls for the wings explained.

• Releases
  
  There may be no difference in the releases from those of a normal wings style BC apart from the addition of counterlung releases. However, individual rebreathers are likely to be customised and all releases should be fully explained.

• Air
  
  Normally, breathing is from the large hoses, but if there’s a problem which can’t be solved, breathing is from a normal second stage or Autoair. This is the buddy’s source of emergency gas, but as it is fed from a three litre pony cylinder the divers will have the ascend immediately if used.

The amount of scrubber life left should be added to the information supplied to the Marshal. When diving with an open circuit buddy (ie someone on a normal regulator/cylinder) their gas supply is the main limit so there is no need for more information.

When two closed circuit divers dive together an estimated time back at the surface should be given, but this is after all something that open circuit divers should be giving too.

Closed circuit divers should always use a delayed SMB when surfacing. As with open circuit divers, the Marshal may want to consider whether a SMB should be used throughout the dive.

The minimum a buddy should know about a closed circuit diver is:

• how to give buoyancy,
• how to ditch equipment, and
• how to get to an alternative air source.

If anyone has any questions about Buddy rebreathers, talk to Ian or Tracey McLean.