CCR Liberty cave diving resistance

Confined spaces, typically caves or wrecks, can be an excellent training ground for resilience. In these environments, contact with solid "obstacles" such as the ceiling of a cave or the structure of a wreck is often unavoidable. During transport, contact with the cave or other surfaces cannot be avoided, especially if divers are transporting equipment via crawling caves.

When an obstacle is hit, it is the rebreather that must often "swerve" or absorb the impact. This often involves sharp or abrasive surfaces, e.g. corroded wreck structure, sharp protrusions in caves due to the genesis of the cave or fillings (speleothems - decorations).

The resistance of the unit can be categorized into three areas:

• The inherent resilience of the unit,
• transport resistance, and
• resistance to diving, especially in confined spaces.

The intrinsic resistance of the unit is determined by the quality of workmanship, the materials used and its philosophy a Fault Tolerant Rebreather, which Divesoft promotes. The quality of the unit's workmanship can also be seen in person at many events worldwide.

Entrance to Juriško Vrelo, photo by Přemek

Installation of the unit in a confined space

Cave diving in most karst areas cannot do without transporting gear through caves, often through crawling caves or single-rope technique through verticals. The unit is often transported by the diver in a semi-disassembled state. With full weight, it is impossible to complete the heavier rope sections or push it through the crawlway; the whole back unit cannot be put into the speleothem.

Subsequent assembly takes place in a confined space with an unlimited amount of sediment, which fundamentally limits the delicate handling of technically advanced equipment. Liberty rebreathers have also been tested in this environment with compelling success. Examples include crawl transport in Chýnov Cave, rappelling down the rock in Alberic Cave, siphon diving (sump diving) behind the Grande Siphon in the North Branch of Bue Marina, etc.

Chýnovská cave, photo by M. Dvořáček

Scratches are inevitable

The Liberty will have no respite even after plunging, especially in the flooded crawlspaces. Contact of the sidemount unit with rock is inevitable, the unit's body grinds against the rock and the lungs are clawed by sharp protrusions. More than once, a diver is left hanging by the hand set cable, typically in zero visibility while trying to free another jammed piece of gear, etc.

With the Classic Backmount unit, the head and buddy light suffer the most. Low caves stirred up halocline or otherwise reduced visibility while swimming... and contact with the ceiling can be difficult to avoid. If a diver hits the ceiling while scooting and it shows up as a small scratch on the buddy light, what more could you ask for? With the cave head cover, all worries are completely put to rest. Proof can be seen in the dives in Juriško Vrielo, the tunnels around Jíloviště, the caves in Sardinia, etc.

We also proved the unit's resilience during last year's expedition to Juriška Vrelo, we left the unit between dives in the cave near the spring, where the relative humidity is almost 100%. The unit was then in the cave for 4 days, completed 3 dives and worked with all sensors without any problems all the time. Not a single oxygen sensor was disabled.

Mine adit, author selfie

• Petr Chmel