Rebreather

A Notion is Born...

I had always been led to believe that the Closed Circuit Rebreather (CCR, box, bag of death or whatever you want to call it!) was the domain of a few brave technophiles. How wrong I was!

It was when open circuit Trimix diving on Pat Dean's Lodesman in July 2004 with Bill Reid's group that I made the decision to dive with a box. Most of the group were using rebreathers, and had only started the previous year. Bill was keen to extol the virtues of the Ambient Pressure Inspiration Rebreather, and over the week I came to warm to the idea of getting one. There is no reliable source of Helium in Paignton so after a days diving I had to travel to Plymouth every other day to fill both my twin 12's with Trimix at £40 a fill, sometimes to find the dive the next day cancelled due to the weather. I was often stuck with a mix waiting for the right dive so in the meantime my diving was restricted or I used my Scooby Gear with My Little Pony. The rebreather guys could just top up their little 3 litre pony sized diluent cylinders from a twinset of mix and replace the Kitty Litter in their CO2 scrubber. CCR divers affectionately call Sufnalime Kitty Litter because; believe it or not it looks like kitty litter. It has been known for some to use their expired Sufnalime as such (no I don't have a cat!).

Out on the Hunt...

That Autumn I decided to get a rebreather, and put my Yamaha WR250F motorcycle on ebay to pay for it. Dave Pelly from Sandford and Down began a search for a good second hand unit for me. This was to prove difficult until after Christmas 2004 because of high demand.  The seller was in Southampton and wanted £3000 for a 6-month-old unit freshly serviced (£4000 new). A deal was done and the seller, Andy Hetherington was travelling to Devon anyway and dropped the unit off, asked me to be a good little boy and not use it until trained and sign some disclaimers in quintriplet in case I had decided to do a suicidal dive without training.

Reality at Last...

I then stood there in my garage thinking, 'What can I do now?' I know, I shall sit there and look at it my new pride and joy. I couldn't use it yet!

Myself and another student sat in Sandford and Down's classroom like attentive puppies eagerly listening to Dave give the lecture for the theory of the Closed Circuit Rebreather, whetting my appetite for getting to use the CCR. We were excited but also had some trepidation since CCR is very different to the open circuit scuba we all know very well. Dave's excellent manner put us at ease and reassured us, and as he went through the classroom material, I thought hey this isn't too bad after all; even I could follow it.

What is it really like...

It was on a blustery February evening that we finally arrived at the Central Pool in Plymouth for our confined water session. There was just myself and another student for the class. He put the units onto us, dressing us up saying 'This bit goes here, tuck that in there, leave that bit alone, don't press this and this goes in your mouth'. In we went, taking my first breath out of what is effectively a bag. The breathe is totally different to Open Circuit (OC) because there is no breathing resistance. The buoyancy was weird at first since the gas just moves from the lungs to the bag and so I could not adjust my buoyancy by breathing. This is a big thing that OC divers take time to get used to. It was crucial to keep a close eye on the PPO2 displays every 30 seconds or so, far more frequently than OC divers checking their air. CCR DIVERS MUST ALWAYS KNOW THEIR PPO2! The other thing I learnt was to close the mouthpiece when removing it underwater or it floods making a horrible gurgling noise.

The drills sounded complicated, but once I understood what was doing, they were actually quite easy. They were designed to train us to deal with the main hazards of the CCR. Quite simply, these are little or too much Oxygen, and CO2 poisoning. The drills were drummed into us until we could do them silted out upside down inside the deepest and dingiest wreck.

With proper unit maintenance and procedures, the likelihood of these problems is very small.

First taste...

With confined waters training done, it was time to get the unit salty.

Dave's very unfortunate incident meant my training was transferred to Ritchie Stevenson at Big Blue. His next CCR course was for 3 days in April, over a month and a half away!  The time came, and Ritchie refreshed us on our drills in the classroom since it was two months since our pool session. We went in at Bovisand, and made my first CCR open water dive. We kitted up and after more briefings, entered the water. He led us along the harbour wall and out along a bottom line. We did some drills and came back. We did 2 dives.

The next morning I stood there in front of Ritchie who had his "I'm sorry mate the weather is just too bad" expression on. We were blown out over the next 2 days that we had arranged.

Will I ever finish...

We scheduled for later in April. I got the time off work for it.

We had got one dive in then Ritchie's suit had become a wetsuit so we had to abandon further training for the time being. I don't blame him since the water was barely 10 degrees C! When he had finally repaired his suit, the next session was sacked after 10 minutes in the water because the visibility was just too poor; one could not even see their mask! This was to make the training take until late May to complete.

We finally dived from Seeker on a wet windy slate grey day in early May sheltered behind the Plymouth breakwater. We finally completed all the drills in 10-16m of water. We completed the Low and High Oxygen drills and bailouts. It was then I had an interesting event to say the least. I had a new Scubapro SMB that inflates from a Low Pressure Inflator. I used my dry suit line, and yes the bag went up OK, together with the contents of my diluent cylinder. The line had free flowed and emptied it in seconds before the diluent valve could be shut down. Ritchie was right there and calm. We made the ascent as normal, and I learnt from first hand experience that the rebreather does not need any diluent during ascent. This is because the gas volumes need to be vented during ascents, and O2 is added to maintain the correct O2 levels.

At last I was certified to use my box, and not a moment too soon. My training had taken over 4 months to complete.

Introducing an Inspiration...

I finally come to introduce my new friend to the TSAC. This first dive was the humble Mewstone out of Dartmouth on Falcon. It may have well been the Britannic with my excitement of using my toy without supervision. My buddy was ever Tekkie Richard Wood. Reached 29m, which was my deepest so far on the CCR. I was don't remember much of the dive because I was glued to my displays to know my PPO2. As confidence grows this becomes more natural.

Scillies...

A week in the Scillies consummated my relationship with the CCR. I put in 10 good dives to really get going. Got to 40m and good hour-long dives. It was here that the advantages of the CCR became evident. The other divers were twinned up on OC. They had to worry about gas fills for each days diving, whereas I could last 4 dives on 230 bar in a 3 litre. My gas bill for the week was six quid for 3 litres of O2.

I also found the rebreather had a warm moist breathe, when the scrubber removes the CO2 its gets warm and moist because of the chemistry in there.

A Retro Step...

Upon return I was involved with a TSAC training dive off Brixham beach. I needed to return to my OC Scooby set for this. I was amazed at how noisy OC is. Those bubbles are deafening! It was also quite hard to breathe at first. I was not used to a DV any more.

This is what it is all about...

I have found the TSAC are a forward thinking club and welcomed the CCR on dives. At first there were a few puzzled expressions as to why I would bring a 'Fridge' onto the RIB. Over time the club members have become more used to it. Some would at first say 'Too Technical' but now know that there is no big deal with buddying a CCR diver.

By July I was up to 20 dives and I had a club dive on the wreck of the Riversdale. I was with Richard Wood. We descended the shot to the wreck, and went to the bow; this had collapsed to one side. I was aware that fish would come close to my silent world, getting in amongst a shoal of the humble Bib. We went to the stern area, onto the quarterdeck looked over the stern to see the screw. We had had good visibility on this one. We dropped down to the screw. I sat there and looked up at the vast hulk above me. I often turn my torch off to make the dive more atmospheric, especially when looking up at the wreck. We returned to the shot, and ascended. I had cut tables for a square profile dive. My planned stops were about 20 minutes, and Richard's longer. I stayed with him until he completed his profile. This had been the biggest dive so far on the CCR, and I look forward to getting some magic gas in there next year.

So what do I think?

As I write I have some 40 dives on the CCR. I feel very comfortable with it. I do feel better after diving on what is the perfect Nitrox mix at all depths. I can now listen to the underwater world so often masked by regulator and bubble noises with OC. I can hear OC divers breathing, and recognise the noise signature of a Poseidon regulator!

The Nitrox CCR (air diluent) actually has more of a depth limitation than air. At 52m the Nitrox CCR would be giving effectively air at a 1.3 bar set point, and deeper would be worse than air!

I have spent this year doing typical club dives to get experience with the box. I propose to do a CCR Trimix course next year to enable me to go deeper to the 60 to 80m ranges.

Is it for you?

It is a big capital outlay to buy an Inspiration Rebreather. The running costs are reasonable though. Whether it is worth it depends on the sort of diving you do. It would work out more expensive per dive for typical club diving. If you want to start doing deeper dives over 50m then it is worth thinking about. You can offset the costs of twinning up on OC to getting a CCR. A good twinset, wing and a pair of good DVs that can cope with the depths will set you back around £1500. CCR diving does require more discipline and maintenance, but it is simple to do. It becomes second nature after a while.

Unit preparation takes about half an hour before and after a day's diving. If you are the 'chuck the kit in the garage still all salty' after the diving and 'Oh bugger my cylinder is empty' the night before a dive type then it is not for you!

If you want to explore many of the deeper less dived wrecks, or simply want something new to add to your diving experience or want and have some money in your pocket then the CCR is the way forward!

Si