After our team of relay swimmers completed the Lighthouse Swim, Tony and I made our way back towards Granger Bay via a meandering route that included a search for the buoy marking the Seli 1, off Blouberg beach. We did not find it.
The Seli 1 under Table Mountain
What we did find was quite disturbing: a hissing, pulsating patch of water beneath which the rusty wreckage of the Seli 1 lies, very close to the surface. There was no wind and very little swell when we were searching for the wreck, and initially we thought it was a school of baitfish disturbing the surface in that way. Fortunately we approached the spot slowly, because if we’d ridden over the wreckage this would be a different kind of blog post altogether.
The sea reveals the Seli 1
We rode around the spot as close as we dared, watching the image of the objects below us on the sonar. The buckled plates of the wreck, where the SA Navy divers did their work with explosives to reduce it below the waterline in 2013, were clearly visible. The wreckage – particularly the shallowest part pictured above – is a definite hazard to any boat with a keel. We couldn’t tell exactly how much clearance there is between the top of the shallowest part of the wreck and the surface, but it didn’t seem to be more than half a metre. I hope it’s more than that, and I also hope that SAMSA pays attention to our request for a replacement marker buoy on the wreckage to warn ships (but considering how many channels of communication I had to try before not getting some kind of error, I haven’t a lot of hope).
Yesterday’s post perhaps left us all feeling a bit deflated. So let’s get to the good stuff.
How is a boat re-pontooned?
First, the glued attachment strips are heated and removed and the pontoons, still intact, are also removed. You can see just how little boat there is once they are off.
Deflated pontoons on the ground
Side view of the boat without pontoons
Front view of the boat without pontoons
Step two is to open each section of the tube, separate the compartments and use them as templates to cut out the new ones. A huge cutting table is used as well as a whole range of markers, steel rulers and heat guns.
Pontooning in progress
The company we used, Ark Inflatables, don’t glue the seams – they weld them instead. So the tubes are all welded together individually and assembled section by section, and then on they go. The pontoons are held to the hull by a series of attaching strips and are also glued to the hull where they meet. Once they are on and secured, they are ready for the third step: accessories.
The various options of what accessories to add require some special consideration. Ark are extremely flexible and helpful when it come to weird and wonderful customer requests. Depending on the use of the boat there are a wide range of options.
We use the jetties in Simon’s Town, Hout Bay and occasionally at Miller’s Point or Oceana Power Boat Club near the Waterfront. Some of these jetties are poorly configured for smaller boats, so pontoon damage and abrasions can be a huge problem. They are also primarily black rubber tyres or bollards to tie up against, and these mark the pontoons. To solve that problem we added four rows of rubbing trim.
We anchor at some of our dive sites and in order to set and retrieve an anchor without damaging the bow we added a really wide rubber buffer and rope channel.
Front channel for anchor ropes
Getting back into a dive boat can be challenging for some, so to ease that issue we added three lines to each pontoon section: a grab line to hold once you have surfaced and reached the boat, a top taut line to yank yourself up on, and a third line, to grab as you exit the water, on the inner wall of the pontoon. This line also serves as a secure place to place fins whilst the boat is underway.
Having spent most of my life around boats I know that anything you have onboard, if it’s not attached it’s going to the bottom, so there are around 25 D-rings on the boat for clipping off anything that you want to keep. An old issue with the boat before was the attachment of the bow rail: it would pop out if a diver was hanging on it, this now has a double set of attachments.
The top of the pontoons take a beating from the sun, people stepping on and off, and of course weight belts and cylinder boots. To solve this we added a second skin down the entire length of the pontoon and these will now be ”wear strips” that can be replaced if the are damaged.
Protective pontoon cover and ropes in progress
Lastly, to maintain the correct pressure when the day time temperatures exceeed 30 degrees and the night time temperatures plummet, this coupled with a sudden cooling once you hit the water, we had them install an over pressure valve on each section, meaning it can never be pumped too hard and if left in the baking sun the excess pressure will bleed off.
Overall, I think it was a job really well done and would recommend Ark to any rubber duck owner wanting to repair their boat. The boat looks a little more ‘”industrial” than it did before, but the reality is it has a task to perform and must be able to do so faultlessly. Asthetics are secondary, but we feel the boat looks rugged, tough and ready to work. Oh, and did I mention… cool!
Sea Dog is a surfski time trial at Fish Hoek beach that takes place every Friday evening, starting at six in the evening. It runs for the last ten weeks of the year, and the first ten weeks (so twenty weeks, during the summer months). There is a gap in between for Christmas and New Year. It has been running for a few years, and a meet is never cancelled for any reason. We can attest to this, having gone down to the beach during a black south easter with bucketing rain, only to see a hardy group of paddlers battling it out behind the breakers in almost zero visibility.
The event is organised by the Mockes of the paddling shop in Fish Hoek, and there’s usually a photographer (apart from me) to document the event. There are usually a couple of marker buoys out in the bay, and the paddlers do a number of laps around them. I’m not sure of the details of the race format, but it starts and ends on the beach. There are participants of all skill levels, from world champions to weekend warriors.
The course ended about here
Lots of action in the middle
Colourful shirts on a turquoise sea
Paddlers in front of the catwalk
Heading towards Clovelly
Rounding the buoy at the eastern extreme of the course
If you’re around, it’s a lovely thing to watch (or participate in, if you’re a paddler) on a Friday evening after work. We sometimes get dinner and take it down to the beach to watch the proceedings.
Yesterday I told you about the test run of Jan Braai’s underwater fireplace. Some repairs were necessary after that day, as the glass had cracked during the test run. The designer added a few improvements and upped the suggested amount of ballast for the final attempt. Weather days just were not playing along so we ended up in the harbour at the Hout Bay slipway on a very grey day. I had Seahorse for boat support, and Craig and Mark were there to assist in-water.
Sinking the braai in Hout Bay
The water looked good. The viz was not amazing, but certainly a good few metres for decent underwater footage. With a cameraman from Atlantic Edge Films, a cameraman from Jan Braai and GoPro and a further three or four GoPro cameras, we were ready to hit the water. Jan packed the unit with wood, firelighters, a grill a lighter and some wors (for foreign readers: boerewors, wors for short, is a type of South African sausage that is typically cooked over a fire) and then shut the rear panel. This panel had glove holes with gloves attached inside, like a chemistry experiment or hazardous materials unit, so the activity in the box underwater could be managed from outside.
We wheeled the underwater braai into the water and swam it out to the buoy and anchors we had placed at the right depth beforehand. Sadly the required ballast had once again been miscalculated, and the centre would not sink to the correct depth. Back to the slipway we went, and the team added rocks and a few hundred kilograms of sand in plastic bags. We swam the braai back out to the required depth and this time it was a success.
The tide was so high that the jetty in Hout Bay was submerged
Once the unit was submerged Jan, on scuba, with two safety divers in attendance, inserted his hands into the gloved openings, took the lighter, lit the firelighters and got the wood burning. The stack had an extractor fan to draw the smoke out and pipes to draw fresh air in, and once the flames took hold of the very dry well prepared wood the smoke was visible above the water.
The underwater braai in action
Jan then surfaced and waited a while for the wood the burn to coals. He then descended again and started the world’s first ever underwater braai. It took around 20 minutes before he surfaced, claiming the wors was ready for consumption. The unit was winched up to above the water line, Jan then removed the rear cover and proceeded to eat the first piece of meat cooked underwater.
The cooked (and some uncooked) wors in the braai after the event
All in all the idea masterminded and executed by Jan Braai was a resounding success and was done to celebrate National Braai Day on the 24th September. The program showing the execution of the idea was broadcast on Kyknet on Friday 27 September 2013.
The designer of the underwater braai makes sure everything is in order
The wors is ready and waiting to be cooked
Checking on the braai as it is moved deeper into the water
There’s been a bit of press coverage – no one has done this before, as far as we know – and there are a couple of videos on youtube documenting the event. Check out a round-up of media coverage here, if you missed it.
It’s been interesting for me, being close to someone whose job is at least partly weather dependent. My job is (alas) not weather dependent at all.
Rain gauge waiting to collect some rain
There are days that aren’t suitable for diving (at least, we think so), and ideally one wants to identify them in advance for planning purposes and to maximise the use of days with good conditions. The result of this is that Tony is very interested in what the weather is doing. There are fairly predictable cause and effect relationships between the prevailing winds and underwater visibility in the ocean around the Cape Peninsula, but there is a host of other variables – such as how long the wind has blown for, and what the air temperature is – that can complicate things.
The anemometer attached to the satellite dish
We (mostly Tony) spend quite a bit of time looking at weather online, particularly as the Thursday newsletter deadline approaches. What we don’t always know (except from the live buoys at Kommetjie and the intermittently working ones in False Bay) is what the weather is doing at home, where we live close to the ocean on the edge of False Bay.
With this in mind Tony’s birthday present this year was a home weather station, a (not entirely selfless) gift that will keep both of us interested and occupied for hours. I chose the Oregon Scientific Anywhere Weather Kit, which comes with a barometric pressure, temperature and humidity sensor, an automatically emptying rain gauge, and a wind vane and anemometer. You can add other sensors if you wish. Wonderfully, when the main unit is plugged into your modem/router, the data collected by the sensors is saved online for viewing on a computer, and a smartphone app (for iOS or Android) lets you check the weather at home while you’re at work, if that’s your thing.
The home screen of the iOS Oregon Scientific Anywhere Weather app
It’s possible for you to see the weather at our house – if you have a smartphone and IF (big if) you care. You just need to download the relevant app (iOS, Android) from the Apple app or Google Play store on your phone, register as a user on the app, and then add Tony as a friend (search for his name and surname by clicking on the “+” button in the Community section of the app, and send him a friend request). Then if you go to “Map” you can search for your friends’ weather stations (or any others in the area that have their permissions set to allow you to view the data). If you don’t know where we live, email Tony and ask him.
The temperature and humidity display of the OS Anywhere Weather app
While we were in Denmark just after Christmas we paid a visit to the Tempo Bådudstyr in the suburb of Greve, just outside Copenhagen. It was fabulous. Tony was genuinely browsing the wares, while I photographed things that looked cool. My favourite items were the mini life vests for dogs (we have seen a lot of dogs on the sailing boats that frequent the small marinas throughout Denmark).
We got a ride back from the boat shop with the pastor of the local Lutheran church, who lived in Glostrup where we were staying. He took us home via the hard standing at the marina where he keeps his little sailing boat. In winter all the pleasure boats are removed from the water because the harbours ice up. They are placed on stilts in huge boat parking areas. In spring when the weather softens, they are returned to the sea.
Please enjoy a small selection of photographs of the maritime delights that can be found in this particular Danish boat store:
A shark exclusion net has for some time been planned for Fish Hoek beach. The net will not kill sharks and other marine creatures like the ones in KwaZulu Natal do, but rather forms a close-meshed barrier that aims to keep sharks out, swimmers in, and everyone alive. For reasons outlined here, the process of designing and building the net has been a fairly lengthy one, and something that neither the City of Cape Town nor the Shark Spotters wanted to be hasty about.
It was therefore a happy day last Friday (22 March) when the first trial deployment of the net was conducted at Fish Hoek beach. The net is a world first, and it will take a couple of practice attempts by the parties involved (the City, the trek net fishermen who will do much of the work to deploy the net, and the Shark Spotters who will monitor it) before it’s a smooth process. The net will be put out each morning (given suitable conditions) and removed in the evening.
The net in its trailer
On Friday I spent the morning on the beach, watching the process, enjoying the beautiful calm weather, and taking photos. I spoke to a number of community members – mostly elderly people who come down to Fish Hoek every morning for a swim – and they were unreservedly enthusiastic about this “historic” project.
There is a press release regarding the net here. I suggest you read it. There’s an album of photos on facebook, here.
Sunrise at Fish Hoek
Having an early morning swim/natter
The net is towed down the beach
Working to get the boat in the water
Trek net fishermen push the trailer into the shallows
Handing off the rope at the end of the net to the boat crew
Ready to commence deployment
The boat pulling the net out to sea
The rope linking the boat to the end of the net is visible here
Team work from the trek fishermen
The pile of net on the trailer dimishes
A pause in the action
The boat heads back for a second attempt
Re-stacking the net for a second attempt
Working with the net
The sequence of work is visible here
The boat makes a successful turn towards Jagger’s Walk
Six hundred experimental octopus traps have been sunk in False Bay, in an attempt to create a new fishing sector.
Sea Freeze, a Hout Bay-based fishing company, last month deployed seven exploratory octopus long lines between Simon’s Town and Fish Hoek.
Each line is about one kilometre long, with two main buoys on each end. The buoys have radar reflectors and lights and are visible about 500m from the shore.
Ropes weighed down with cement drag the lines down vertically. The traps are placed horizontally along the lines, far beneath the surface of the water.
The above info courtesy False Bay People’s Post. I can only wonder at the risk of entanglement for whales and other large ocean creatures!
Two stroke engines may smoke, but not as much as this navy ship
On a lighter note…. Weather and ocean this week have not been too diver friendly and the southeaster blew so hard yesterday I could hardly get out of the harbour in Hout Bay to test the new motors on the boat. The water however was clean and the viz good.
Today I was out in False Bay and the water looked a dark greenish brown colour, very patchy and not great surface conditions. At Photographer’s Reef I could not see the top of the reef when the sonar said it was 4 metres deep. The same at Atlantis and the Brunswick.
There is some northerly and westerly wind coming, but not a lot so I doubt we will have anything better than 5-6 metre viz in False Bay. There is also a little rain in the forecast to contend with. Hout Bay will probably stay clean as the air temperatures for the next few days barely bump the 20 degree mark.
Fitting the new motors to Seahorse
The weekend
There wasn’t much diving last weekend or during this week but there was much boat work to be done and we have replaced both motors, been out twice to test them and I am happy to say all is well again.
We will do a double tank dive on Saturday really early, as I have a family in Stellenbosch expecting me there late afternoon for training. On Sunday we will do two launches, both shallow. Whether it’s False Bay or Hout Bay depends on the conditions we find tomorrow and Saturday.
Back home with fully functional motors!
Travel
We are heading to Durban on the long weekend of 16 June, and staying a few days of the following week. If the weather is favourable we will do a day trip to Aliwal Shoal and if it’s atrocious we will dive the aquarium. We plan to dive some of the interesting wrecks and reefs that Durban has to offer.
We’re booking our Red Sea trip next week. If you’re interested in “accidentally” ending up on the same liveaboard as us, I’ll give you details as soon as it’s finalised…
Sometimes a weather forecast is useful, and sometimes being able to scrutinise current weather conditions from the comfort of your couch is useful. Maybe you want to go diving, and suspect (quite rightly) that weather conditions in Kenilworth or Durbanville may not correspond with those at your planned dive site.
Maintenance at Roman Rock lighthouse
I therefore bring you the following:
There is a data buoy in False Bay, operated by the Centre for Observational Oceanography, which is connected to the Oceans and Coasts section of the Department of Environmental Affairs. The buoy data is here, and shows wind speed and direction, sea surface temperature, atmospheric pressure, and some 7 day charts of historical data. The rest of the CFOO website has some interesting stuff on it, if you can overlook the early 1990’s design vibe. The position of the buoy is noted in longitude and latitude – it’s in False Bay, but I’m not sure exactly where.
There is a CSO weather station at Roman Rock which reports wind speed and direction, air temperature, and barometric pressure.
There is another weather station at Roman Rock lighthouse, which reports (when it is working – not often lately) wind speed and direction, air temperature, barometric pressure, humidity, and solar radiation. There are charts showing these readings over time, and a summary table at the bottom of the page. It is updated every half an hour. The nice thing about this data is that you know exactly where it was measured.
Fish Hoek Beach Sailing Club has a live weather station at Fish Hoek beach that will give you an excellent idea of (particularly) when the south easter is trying to blow the south peninsula away!
Wind speeds are reported in metres per second or knots (check carefully). There is an excellent wind speed converter here. Just fill in the value you have in the box corresponding to the units it’s reported in, and click convert to see the wind speed in all the other units.
Update: The links above come and go… Apologies in advance if any of them are broken. Sometimes they work, sometimes they don’t for months at a time. I’m leaving them here, however, for when the equipment gets back online.
Scientists working off the coast of California in the US have released an app for iOs mobile devices that enables users to track great white shark movements in (virtually) real time. Making use of a network of fixed buoys and drifting wave gliders. The initiative is part of the Global Tagging of Pelagic Predators project, which uses tags and listening devices to track the movements of migratory ocean species such as tuna, turtles, marlin, and several kinds of shark.
The map shows the area of coast that is marked by buoys and wave gliders
The white sharks for which this app (called “Shark Net“) shows the tracking data are equipped with acoustic tags. When they pass within about 300 metres of a wave glider or fixed buoy, a signal is registered, the shark’s location is calculated, and the data is sent to a listening station with a central repository of shark tracking data. The system obviously only tracks sharks that are tagged, and only when they pass near a buoy. The technology for the wave gliders is pretty nifty.
A diagram of each buoy and wave glider shows its workings
The number of tagged sharks visible in the app is reported to be increasing
One of the underwater listening stations after several years at sea
The information collected by the scientists is useful for identifying the hotspots along the Californian coast where white sharks congregate in late summer (much as our local white sharks move inshore at the start of summer) after spending time further offshore at the Farallon Islands and beyond. It also helps to identify “highways” or particular routes that the sharks favour to move between feeding locations. Allowing the public to view the data as it is being collected serves several purposes – not least, allowing us to see these creatures as they move about in their domain, to form attachments to them and to develop a special interest in their behaviour, and to understand something of how scientists work to understand the ocean ecosystem and its inhabitants.
Each tagged shark has a bio and photograph included in the app
You should also check out the GTOPP publications page which has pdf downloads of the research that the program has produced.
Año Nuevo is the site of an elephant seal breeding colony and hosts an underwater receiver
