Tony, Kate and I recently completed the theory portion of the CMAS (here’s the South African branch) compressor operator course at False Bay Underwater Club (FBUC). The theory component involved a 2 and a half hour lecture delivered by a CMAS instructor, and a written (no multiple choice!) exam. The manual was written by Peter Southwood, the local wikitravel guru.
Operating a compressor is reasonably simple: there’s a well-defined sequence of actions that need to be performed on start up and shut down, as well as constant monitoring of the compressor during the filling process. Some compressors require bleeding off of accumulated moisture and residual oil throughout the filling process. As long as one is circumspect regarding which cylinders one agrees to fill, it is a safe activity.
Turns out in South Africa (and elsewhere) compressor operation and standards are heavily regulated. Given that compressed air cylinders are used in a range of life-critical applications such as fire fighting and scuba diving, this makes good sense.
The practical portion of the course requires us each to perform 20 cylinder fills, including a number of compressor start ups and shut downs. This must be completed within a year of doing the theory component, and signed off. I expect that getting my hands on a compressor and actually doing the fills myself will clarify a lot of the questions I had, and bring those schematic diagrams in the notes to life!
On Saturday last week we participated in the OMSAC underwater coastal clean up in Murray’s Bay Harbour on Robben Island. The weather was magnificent – we had awesome boat rides there and back on the old Robben Island ferry, crusing in between moored container ships and spotting seals.
The Old Mutual Sub Aqua Club organisers had done a fantastic job, and the Metro Rescue team was on hand in their rubber duck. They laid a line down in the harbour demarcating the area in which we were to start the dive (since the regular ferry was still going to be in and out, we had to take care). Entry was via a giant stride off the bottom of some steps in the pier… As it was low tide, the stride was pretty giant. My first time, and lots of fun!
This is our entry point... Duck waddle down the steps, and giant stride off the edge!
Once we were in the water, however, it was a different story. Armed with kitchen scissors (the biggest adventure my lowly pair has ever had), knives and mesh bags to collect rubbish, we were to scour the harbour bottom for debris. Visibility, however, was appalling. So appalling that I spent much of the dive in a state of abject terror – at times it went down to zero, and I couldn’t even see my hand in front of my face. I held onto Tony most of the time, and couldn’t even see the far side of his body. We surfaced once or twice for fear of crashing into the harbour wall without seeing it, and descending again was frightening because I didn’t know what was beneath me and had no sense of depth.
Murray's Bay Harbour at Robben Island, with our entry point to the right of the jetty, and our exit point to the left between the ships.
The bottom of the harbour is mainly covered with very fine white sand, and the water is permeated with it. There’s also a disturbing suction effect in parts of the harbour – one feels as though you could sink quite deep into the sand if you put your mind to it. In the part of the harbour where the new ferry docks, there’s quite a lot of ridged, smooth rock on the bottom, overgrown with sea plants.
We didn’t see much life – I am sure it’s there, but the visibility precluded much underwater naturalism. On the surface I spotted a night light sea jelly, and Tony saw a puffadder shyshark. Bank and Cape cormorant nest on the breakwater at the entrance to the harbour – we were cautioned against disturbing them.
Cormorants nesting on the breakwater at Murray's Bay Harbour
Tony had decided against bringing his underwater camera because we thought were supposed to be cleaning up, not shooting photos, and at first he was kicking himself because every second diver had brought theirs… However, after seeing the water conditions, we realised he was not missing out on anything!
The harbour was built in 1939 along with an airstrip and gun batteries for military purposes. It’s not a very busy place nowadays – the only real traffic is the Robben Island ferry a few times a day. Tourists don’t hang about there much either – they get whisked away on tours – so there’s not that much opportunity for them to drop litter into the water or let their chip packets blow away. Despite that, I was expecting a lot more rubbish than we found. Part of it was the poor visibility, but we didn’t see a lot of junk at all. Some awesome old cooldrink bottles were found, some net, plastic bags and bottles, and a few other bits of bric a brac.
Dive date: 18 September 2010
Air temperature: 24 degrees
Water temperature: 14 degrees
Maximum depth: 5.5 metres
Visibility: 0.3 metres (not kidding – an optimistic estimate)
Dive duration: 33 minutes (that’s time underwater)
That's Tony and me toting our gear down the jetty after the dive
There’s a gallery of more photos up on the OMSAC website.
