a lot easier to understand and retain . Over eight hours I learned the nuts and bolts of rebreather diving , from controlling my breathing to understanding what the unit was doing , and why .
The biggest challenge for me was understanding buoyancy control and the relationship between Dalton ’ s and Boyle ’ s law . Hovering in 6m of water and manually adding O2 felt challenging , while feeling light at 6m and continually venting the loop felt exhausting . I was continually telling Fran and Scott that I needed more weight , as I felt that was the only solution . Later on , I was laughing and handing the weight back to them ; by then I understood what the unit was doing , and was able to anticipate what was likely to happen .
Although rebreather diving requires an investment of kit and time , transitioning to a CCR unit has been one of the best decisions of my diving journey . The course is packed with information and will underpin your diving with greater knowledge and a new skillset .
Dave ‘ Pegs ’ Pegler emerges from Plymouth Sound
Dave ‘ Pegs ’ Pegler writes about teaching the Mod 1 Top Up Course
Only one theory session was
required , which introduced helium into the breathing gas and was then followed by a planning session . Three plans must be prepared : base plan , worst case and BO ( bailout ). During this process , students were introduced to the possibility that they may get to the bailout plan , realise that they couldn ’ t carry enough gas and have to start over again !
We had planned to carry out the two 40m dives at the NDAC site in Chepstow , but Covid changed our plans . This meant relocating to the shore dive Eastern Kings in Plymouth , which can only be dived one hour before high and low water . The tide times had been carefully selected to allow both tides to be dived in daylight , but this meant a really early start and entering the water almost immediately after daybreak .
In turn , we ran through our kit and predive preparations , noting configuration differences . Next was a final talk-through on rebreather emergencies and responses . Low tide saw us walking across the beach , which is never easy in a rebreather and stage , so the water taking the weight was very welcome .
Rain earlier in the week had reduced the viz in the shallows to 1m or less , which meant that very close student control was necessary , though the clarity improved at depth . We followed the rock slope down to 40m , then swam gently with the current north-west until we met the rock wall again . A power cable between the shore and Drake ’ s Island acts as a guide , so we followed the bottom of the rock slope at 30m until we found the cable .
As we ascended the wall it was time to complete our planned decompression stops . Our three heads surfaced exactly on 60 minutes – right underneath the bench where we had kitted-up . The fourhour surface interval was spent with a burger and chips , followed by a walk in the welcome winter sun .
It was soon time to start the second dive with a student-led kit check ; it was a similar dive to the first in order to confirm student competence . This time it was high tide , so no long walk across the beach ; but unfortunately visibility hadn ’ t improved and the current seemed to have a mind of its own . We found the cable , ascended and made our deco stops . Welcome hands were waiting for us to carry stages . Then we conducted postdive actions with the units and a debrief . Then the best bit , smiles and animated chat about the dive and what was that current all about ? A long but rewarding day .
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