I’ve now had the RB80 rebreather 5 months since passing the class in February. The trip I’d arranged to France in July meant it was time to take it cave diving. I arranged to go diving with Clare, JP Bresser and Anne-Marie. We’d be diving in two separate teams but it always makes more fun to have some friends along. I’ve steadily built up the hours on the RB getting some experience and dealing with some issues. So far I would say it has mostly been a pain the arse! Compared to the ease of throwing OC kit in the car and just going diving it’s a lot more hassle. However as I’ve started diving it on deeper ocean dives it’s started to make a little more sense. On a 60m dive seeing the guage barely move on the bottom does give you a little more flexibility. Its not wonderful – it has just shifted the limiting factor to carrying sufficient bailout and how much deco I’m prepared to do. The trade off is the increased preparation time and added risks.
What cave diving brings is a more stable environment and a predictable exit route. The ability to stage deco gas as you travel into the cave and use bottom stages means a much larger number of stages can be managed. I would be dropping 02 at 6m and 50% at 21m and then travelling in using trimix bottom stages. So a 4 stage dive is only 4 stages for the first few metres and then starts getting easier.
French cave diving is a very different experience compared to say Florida or Mexico. I have to say I don’t find the journey from the UK that bad and I do like the scenery in the South of France. We were staying at a hotel next to Lynne’s dive centre (well it’s a fill station). Each day after breakfast at the hotel we’d stop at a Boulangerie to buy bread, croissants etc for lunch. JP and Anne-Marie’s french is better than mine or Clare’s which made our lives easier 
We started the trip with a swim dive into Ressel with a nitrox bottom stage plugged into the RB. As I reached the entrance to Ressel it was amazing to see that it had changed. A semi-collapse by the entrance has created a much smaller opening with gravel now only leaving a small space to enter. Once inside though the cave looks very familiar. We set off down the passage following the main line. Huge great slabs of limestone lie on the floor of the cave. We reach the first T and turn left down the shallower route of the cave. We carry on at the next T and reach the drop off at 350m odd in. Looking at my pressure guage the RB is really doing its job. We slowly exit the cave and after a brief safety stop surface into the warmer river water and the sunshine.
After lunch we go for a second dive this time with JP and Anne Marie with the plan being a photo dive. JP would take pics with Anne Marie providing lighting. Myself and Clare would act as models. This was great fun to do. On the RB it really was easy, buoyancy control is a doddle and you don’t need to worry about exhaling and ruining the photo with tonnes of bubbles obscuring your face.
The following day we’re back at Ressel. This time for a deeper dive so it’s 4 stages and a gavin scooter. This takes a lot more effort to carry down to the waters edge and to prep all the kit. Clare falls over on the goat track and jars her neck and scrapes her arms and legs on the gravel. Its tough work in the heat and we need a break before pulling on drysuits. Once we are in the water and its all strapped together disaster happens and my light fails to strike. I’d tested it when putting it on my kit at the side of the water so it had broken either getting in or when managing the stages and scooters. At this point JP saves the day and produces a halogen 50W slug from his pocket. As I use EO connectors I swap over the slug and move my goodman handle over. Having used it for a dive I have to say there is nothing wrong with halogen lights other than the burn time (it ran out 20m shy of the exit).
We get going and scooter into the cave. We drop the 02 at 6m and precede to the drop off. We entered the cave on our 50% bottles but used neglible gas going in. At 21m we plug in the twin 12’s of back gas while dropping the 50% and then plug in a bottom stage to start the deep section. With twin 12’s wholly in reserve we kept a full bottom stage in reserve and used a second. This gave us 46L of trimix which with the RB producing anything up to an 8:1 efficiency ratio meant we effectively had over 300L of gas. However the main issue becomes what do we do in the event of an RB failure. Worst case scenario would be a the loss of the RB at max penetration.
We descended down the shaft which fairly soon reaches 45m as the deep section of the cave begins. Despite scootering we headed in at a steady pace by winding the prop back, this gave me plenty of time to take in the cave and pick out features which would help me navigate. The cave is much bigger in the deeper section and the vis was about 7m or so, quite often you couldn’t keep the whole cave in view. I had been warned the line wasn’t good but it was actually pretty reasonable. I quite liked the scenery in this part of the cave. The water has carved the passage through the rock and left fascinating structures. We reached the deep T at about 850m in and Clare asked me if I wanted to drop the scooter and swim. I agreed so we left the scooters as big cookies on the line and headed right on the shallower path. We were now in the mid 50’s, 15mins in the deep section and my stage still has 180 bar in it. We swim on and with the slower pace that swimming brings I’m able to spend more time marvelling at the cave. We reach some sharp turns in the passage and the line heads shallower. We swim through some narrower twisting passages which I’ve heard described as a switchback. I don’t know if the vis improved or it was merely my perception as I could see all the walls but the cave seems crystal clear. As the cave starts to deepen I look at my bottom timer and decide it’s time to go. We are over a 1km in, the water is only 12 degrees and we’d already built up a load of deco.
We swim back to the scooters and the deep T and once we’ve picked them up we head for the exit. I turn the prop right up on the gavin now and get going. We reach the bottom of the shaft and begin our deep stops at 39m. We reach 21m and get ready to pick up the 50% stages. Clare puts her scooter and both bottom stages on the line while she picks up the 50%. I struggle a little as my light is missing the back loop (had to swap the light head to a halogen slug) so I can’t clip it off. I resort to resting my light on a rock or round my neck balanced on the loop while I juggle gear much to my buddies amusement. Once the 50% is plugged into the RB we start timing our stops. We deco via the shallower path in the cave – not something I’d considered before but JP suggested it. It’s actually a nice route and means when we hit 10m we can just hit the trigger and head out. By the time we can see daylight we’ve been in the water 2 hours already and still have some time to spend on oxygen at 6m. Clare’s had a minor leak most likely via tendons on the wrist seal (often happens to me when scootering) while in my dry gloves I was dry and quite happy. When she starts shivering we decide to move up to 3m and into the warmer river water to finish the last bit of deco.
We break the surface and the warmth of the french sunshine is fantastic, 12 degree water does get cold after a couple of hours! After a sufficient surface interval we have the joyous task of humping all the gear back up to the car.
We went back to Ressel for some more dives. On the day after the dive described above I decided to just do a dive in the shallow circuit as I was just feeling uncomfortable and didn’t want to push it. As it happens Clare’s RB had a minor leak ehile exiting and while it still worked we were grateful we weren’t stuck doing lots of deco.
I would add that while diving Ressell we stuck to the traditional route to the water and avoided crossing the local farmers land. I’d urge anyone else visiting to do the same and respect the local land owners. People trespassing risk upsetting the locals and getting access banned for all visiting divers.
On the trip we also went to dive Landenouse. We were careful to drop kit off by the entrance and then move the cars away from the site. JP and Anne Marie were well experienced with pulleys which turned out to be very useful! We winched all the gear down to the water with Anne Marie in place in a drysuit to clip it all off to a line. We were doing another photo dive today and would be diving open circuit. Once kitted up in the water we descended down into the cave. I have to say the lower stress level of OC was a really nice relief compared to the RB80 and given the shallow nature of the cave it was appropriate kit for the dive.
We got some nice photo’s of the cave but JP and Anne Marie all too soon thumbed their dive as they were diving stages whereas myself and Clare we’re diving 1/3’s of our twinsets. With us off the hook as photo models we could now just dive. Landenouse is a lovely cave, a very pretty passage which twists and turns. Vis was around 10-15m and it really made the dive for me. We had a lovely moment where the line was up in the ceiling and it seems to vanish. In fact the tunnel folds back over the top of itself but it is a suprise as it almost looks like the cave ends. In the end we thumb the dive on time although I was not very far from hitting 1/3’s.
All in all it was a great trip to France and nice to use the RB80’s in a cave and really see the benefit. I’ve always believed the GI3′ism “don’t use an RB unless you need it”, on this trip I felt I really put it into practise. I’m planning to take the RB cave diving again but where it makes sense. Combined with a scooter it really does expand what you are able to do and allow you to just see whats around the next turn of the passage.
