A relaxing 11.00am ropes off Monday morning and an early arrival at the marina car park for plenty of time to fettle with Debbie Redbare. Once on board Maverick and chatting to skipper Chris, the previous evening’s discussions of the SS Unity and buddying him were scuttled as helm Don couldn’t make it.
Divers for the day were me, five Polish guys on a tec course and another chap who ultimately failed to arrive. After a detailed boat briefing, the decision was which wreck site? The Lusitania or Pommerania (not to be confused with similar sites off Ireland and Cornwall). Flip of a coin and the Pommerania was sealed.
It was too hot. Forecast temperatures were 28degC rising to 30degC by noon. So it was a gentle transit to take in the sea breeze. Once on site and the shot deployed, we could see that the current was still running and with my inquisitive hat on, started to ask Chris how he plans his dives, how he calculates Ropes Off times, dive times and what he means about clean and dirty tides.
With my Padawan braid firmly affixed, let me explain.
Unlike many other waterways around the British coat, the Strait of Dover is quite unique as it is indeed, a channel. Water will flow to the North Sea from the Atlantic, turn and run back in a cycle of flooding and ebbing tides. Local skippers name these tides “clean” and “dirty” as the flooding clean and the ebbing dirty, the dirty pulling crud from the Thames Estuary which can on times negatively affect visibility. The next consideration is spring and neap tides and the effects on them by the moon. The toing and froing of the tidal flow is a most important consideration. Simply, the Channel has considerable more water traversing on a spring compared to a neap tide. Thus the best time to dive Dover is a neap tide where the slack water window is it’s longest. With me so far?
My next question was, how to calculate slack water?
The answer to that was, buy a copy of the Dover Tide Tables and a nautical chart. The Tide Tables will tell you the high and low tides and the tidal diamonds on the chart will show you the slack window. That’s a lot of calculations for sure but as Chris explained, it’s the experienced local skippers who know the anomalies from the written word and at what time slack will be each side of high tide.
With a copy of tide tables in hand, Chris explained to me how he calculates slack water, a physical number of hours before and after high water. Simply identify the neap tides from the Tide Tables, identify the high tides and calculate either a flooding clean or ebbing dirty dive time. However, that doesn’t mean you can only dive a neap tide, it just means that the slack window is the biggest, as there is simply not that vast expanse of moving water having to stop and turn around compared to a spring
Flooding clean tides on springs can arguably give better visibility with more cleaner water flooding from the Atlantic, but you will find your dive depths deeper and a shorter slack.
From these discussions, I now knew that this was a pre-high water dirty tide. A waning gibbous moon, coming into neaps later this week. Thus slack water would be pretty reasonable.
Back to the dive and as you may have guessed, I would be diving this one solo. If I had said I have never dived solo before, I would be lying as I have ascended many times on my own. As previous open circuit dives in minimal visibility too, in theory I have dived alone as well. That said, I have not done any solo courses, but have been diving in a self reliant basis for many years. So with a little nervous anticipation, I kitted up knowing that I could abort at anytime. One thing was for sure, your mind becomes extremely focused. Checking, double checking and triple checking everything is on, secure, functional and you have a minimum two of everything.
The nice thing here was this. Whatever way the dive went, I could focus on what I wanted to do without considerations of a fellow buddy.
As some will know, I have been struggling with ascents with Debbie and here was my time to get to grips. I had added an additional 1KG for this dive. I had figured that with a new aluminium suit inflation bottle, maybe it was too buoyant as I also have been finding it hard this weekend to descend the first few metres. With a bank of fog heading towards us from France, we were told to come back up the shot. Ideal for me as I still wanted that tactile reference.
Once in the water a slow descent to 31 metres and once settled with buoyancy and PO2 stable, a gentle rummage around the local vicinity of the shot. Visibility was a good and clean 2 to 3 metres. Nothing too much to talk about, other than one crab who seemed increasingly interested in what was going on around him.
My memory was that one of the key principles of solo diving was that the dive should never be a technical dive. No physical or decompression overhead. So as soon as Debbie started flashing her little white light, it was time to go home. I haven’t downloaded the logs yet, but about 27 minutes at 29 metres.
Up the shot was a slow but meaningful ascent maintaining trim as we went. I had been previously instructed that I can switch off the diluent and manually inject O2 to control the PO2 and ascent. I know that’s what I should do, but I wanted to see and experience my course learnings of everything automatic. Inch by inch we ascended the shot, an eager eye on the lowering PO2 then “pssst” as a dollop of O2 is injected. Everything felt OK. A dump of gas from the drysuit and nasal dumping of loop gas seemed to be working well, trying all the time to find that minimal loop. Passing 20 metres I felt quite floaty and now we were onto oral loop gas dumping and out of trim to get gas from within the feet of my drysuit to the shoulder dump. And back into trim.
I saw the PO2 value dropping to around 1.05 and as sure as eggs are eggs, a long “psssst”, increasing to pass 1.28 and a lot more floaty. Holding onto the shot, more drysuit and oral dumping and up a few metres more to a lower 1.11 and you’ve guessed it, “pssssst”.
At six metres I steadied myself and all was well. PO2 was stable and I was on minimal loop. However I still felt quite floaty.
Dive time around 40 minutes, 2 to 3 metres visibility and 18degC water temperature.
For sure, there is a mental block here somewhere and I just need to find a way through it.
Back on board, tea and sausage rolls. Kit secure, my task again was to hook the shot. No poles in the water today. A gentle transit back to Dover, Chris allowing me to steer Maverick home and into port.
A very hot day and pleasant dive with lots of learning. And the great thing about diving a dirty tide? The pontoon steps are more horizontal than vertical to make kit carrying back to the car a lot easier.
A brilliant three days and I look forward to going back another time. Thanks once more to Chris and Tom for making me welcome, Chris again for the mackerel, to Steve and Glen for their wit and banter, Sidemount Simon and the Basildon BSAC boys for a cheeky Bitburger and of course Debbie who remained #SolidGreen throughout.