Diving Thoughts

A diver has died while searching for survivors on the wreck of the Cheonan, which sank after an explosion last Friday. The current thinking is that the ship hit a North Korean mine, in disputed waters. Although the Defence Minister has said it could have been either a mine left over from the Korean War (1950-53), or one that was deliberately sent floating towards the South Korean ship.  There is also the possibility that there was some sort of internal malfunction.

46 crewmen are still missing and divers have been trying to get inside the vessel which has split in two.  The South Korean military have said that the diver lost consciousness while searching the wreckage, but the cause of death has not been reported. A second diver has apparently been taken to hospital. Conditions on the site have been described as very murky with strong currents.

There is more information on the BBC website.

New Zealand’s National Institute of Water and Atmospheric  Research (NIWA), has been tagging great white sharks around Stewart and Chatham islands for the last 5 years. So far they have tagged 25 with tags that stay on for 6 – 9 months before floating to the surface. The biggest shark they have tagged is nicknamed “Shack” and is a 4.8 metre long. Shack has recently set a world record for the deepest known dive by a great white, of 1200 metres.

NIWA’s research has shown that between April and September the sharks are moving from New Zealand to warmer waters during the winter. One shark was found to have spent 6 months in Norfolk island, which is in the Pacific, north of New Zealand.

The research aims to improve our knowledge of the sharks’ behaviour and habits, which may help to prevent them being accidentally killed by the fishing industry. Although with the price of shark fin being what it is, I suspect it won’t help them being deliberately killed by the shark fin industry.

More on this in the New Zealand Herald.

In support of Earth Hour, we are all being encouraged to turn lights off from 8:30pm on Sat 27th March 2010 for one hour. This is intended to show the stand millions of people around the world are making against climate change.

You can find out more about it on the WWF – Hong Kong website.

On 26 June 1918 the Wimmera, an Australian passenger ship, hit a German mine north of New Zealand. She sank with the loss of 26 lives out of 151 passengers and crew.

Now Mike Hodson, an Auckland electronics expert, and his team claim to have found it in about 90 metres of water.

During the First World War a German raider, the Wolf, had laid mines between Cape Reinga and the Three Kings, off Northland. An inquiry at the time was told that shipping notices to skippers advised that the mines were “not a menace to navigation”, but Captain Herbert Kell was blamed for not taking a more northerly course to avoid the minefield. Captain Kell went down with his ship after supervising the loading of lifeboats.

The wreck is in 90 metres of water, and while it has not yet been positively identified, the people who found it are convinced that it is the Wimmera.

The photo comes from the New Zealand Herald’s website, which has more detail of this story.

This is a photo from the Guardian’s website. It is the first of a sequence of 5 of a great white shark investigating three divers in a cage in Mexico. Unfortunately they seem more interested in emphasising that one of the divers is “fending” off the shark, and punching it on the nose, when his hand doesn’t look as though it’s anywhere near its nose. Having said that his hand is definitely touching the shark. The second diver looks as though he would have got some close-up shots too. Meanwhile their mate is bravely hiding behind them both, at back of the cage – just where I would have been!

Anyway it’s quite a good sequence of photos in lovely clear blue water. You can see them on the Guardian’s website.

OK, so they don’t surface in the middle of the night, crawl up the beach, climb trees and start snacking on coconut leaves. Instead scientists artificially fed one of the most common species of deep sea fish on plants, and in doing so they demonstrated that these fish have much wider tastes than previously thought. The implication is that fish may take advantage of terrestrial plants that have been blown or washed into the seas. Dr. Rachel Jeffreys of the Royal Netherlands Institute for Sea Research is asking “Because these fish are eating spinach could they then possibly feed on phytodetritus and so be affected by changes in phytoplankton communities as a result of climate change?”.

Researchers used a rig containing spinach as bait and a video camera was placed at a depth of 3000 metres. Soon afterwards 3 species of fish, grenadiers (Coryphaenoides armatus and C. mediterraneus) and cusk eels (Spectunculus sp) were seen eating the spinach.

You can read more and see a video of the fish feeding on the Earth News section of the BBC’s website.

I have a borrowed OMS twin tank wing, whose power inflator was sticking open, so that when I pressed the button to inflate the wing, it would continue pushing air into the bag even after I’d stopped. The only way I could dive it was to disconnect the inflator hose and inflate it orally when necessary.

As a reminder for next time, with the usual caveats of “Don’t try this at home” and “this may not be the right way to do it”, and “Don’t come crying to me if it all goes horribly wrong”, here’s how I fixed it.

1. Take the inflator valve off the wing’s hose.

2. The air intake nipple doesn’t have a hexagonal nut to unscrew, so use a pair of pliers to unscrew the nipple, having wrapped them in cloth so as not to damage the metal.

3. Then take off the o-ring from the nipple

4. There are two grooves on the inflator button, one on either side. Use a pair of snap ring pliers (circlip pliers) to grip either side of the red button and unscrew the inflator valve.

5. Use 6.5mm socket wrench to take spindle out of inflator barrel.

6. Push the pin out of “wing-end” of the plastic. If there is a fast pull-dump on the corrugated hose, this pin is to hold the wire that connects to the shoulder dump valve. This OMS one doesn’t have one, but it does have the pin.

7. Use a pair of pliers to grip the outlet valve on the end. Push a 9/16″ socket into the other end and use it to undo the nut, allowing the outlet valve to come free.

8. Take off all the o-rings and discard (or retain if you’re really short of money and they’re in particularly good condition)

9. Soak all the other parts in an ultrasonic bath for 10 minutes or so.

10. Rinse and dry all parts.

11. Get a new set of o-rings ready. Put the 2 small ones onto the spindle and grease them with silicone grease

12. Put the rest of the o-rings on and grease

13. Put spindle through inflator barrel and put spring and button on. Use 6.5mm socket to tighten. This should be hand tight.

14. Screw inflator barrel into the plastic. Don’t overtighten as you risk damaging the plastic.

15. Screw air inlet nipple (with o-ring) into plastic. Don’t overtighten as you risk damaging the plastic.

16. Put paper round the deflator button to prevent scratching and grip with pliers. Then use 9/16″ socket wrench to tighten nut, locking deflator button in place.

17. Put the pin back in.

18. Hook the the inflator valve up to a regulator on a tank and make sure that it’s working. I do this before reconnecting it to the corrugated hose in case it doesn’t work and you have to cut it off again.

19. Use a cable tie to fasten the inflator valve back to the corrugated hose and reconnect to the wing / BCD.

20. Test again with a regulator.

You’re done, but be careful with it when you take it out diving.

Steven Schwankert is a diver and journalist based in Beijing. He has been along to SCDC’s Thursday night club night on a number of occasions, and gave a hugely entertaining talk on diving Lake Khovsgol in Mongolia. Around that time he had embarked on a new project which is just now coming to fruition. He was researching into the story of HMS Poseidon.

HMS Poseidon was a Royal Navy Parthian class submarine which sank after a collision on 9th June 1931, north of Weihai in Shandong province. In the first ever successful deployment of proto-scuba escape equipment, 6 of the 26 crew managed to get back to the surface after the sinking.

But wait… There’s more…

China secretly salvaged the submarine in 1972 and the final resting place of the remaining crew is unknown.

Steven has written a book – “The Real Poseidon Adventure: China’s Secret Salvage of Britain’s Lost Submarine”, which should be published shortly. He has set up a Facebook group for people who are interested (from where I borrowed the photo above).

I’ll post more information about this as it becomes available. And if we’re lucky we might even get Steven along to give us another talk the next time he’s in Hong Kong.

HMS Victory was Nelson’s flagship at Trafalgar, but it was the 6th ship of that name to serve with the Royal Navy. Its predecessor was also a 100 gun ship of the line and was  launched in 1737. However it sank in 1744 in the western approaches to the English Channel with the loss of 1100 men, after hitting a major storm near the Channel Islands. Its topmast was washed up in Guernsey but until 2008 that was the last anyone had seen of her.

In 2008 the salvage company, Odyssey Marine Exploration, found the ship and is in negotiation with the UK’s Minstry of Defence (MOD) trying to come to an agreement to salvage the wreck in exchange for a cut of the profits.

Recently marine archaeologists have found a human skull and rib bones underneath a cannon on the wreck.It has not yet been decided if these should be recovered and then either re-interred, or studied.

Two cannons have been recovered from the wreck, a 12 pounder and a 42 pounder.

There is more information from the Guardian’s website, from which the above photo came.

Seven of us were round at SCDC‘s Diving Officer’s place on Saturday for an Equipment Maintenance workshop. After depositing my entrance fee (a sixpack) in the fridge, I took a look at their dining room table. The last time I’d seen it was on New Year’s Eve when it had been covered with excellent German food. Now it was covered with what looked like Black and Decker’s entire product range. There was a wide variety of tools, one or two of which I knew what to do with, and some of the others that I didn’t dare think about.

Since I was late I found that I’d missed Andreas showing how to disassemble Catheryn’s Halcyon inflator valve. But because I’ve had to clean my own out on several occasions, I wasn’t too disappointed. Continuing with the inflator valve theme, I’d brought along one from an OMS wing which was sticking open and filling the bag up every time I pressed it. Before long that was in pieces on the table and all the metal and plastic parts were dumped into an ultrasonic cleaner full of vinegar for 10 minutes before being rinsed and dried. They came out looking considerably shinier and newer. Andreas had prepared well by sending Gabi out to buy several sets of o-rings for different types of inflator valve. Using them we put the valve back together again and tested it. Not only did we not have any extra bits embarrassingly lying around on the table, but it also worked flawlessly. Hopefully this means that next time I dive it it won’t be trying to kill me.

Shortly after this Paula arrived. She took one look at all the equipment on the table and pointed out that the only things  that she had were vinegar and a hair dryer! Now was the turn of her inflator hose, this time from a Seac BCD. This had the same ultrasonic vinegar bath and new set of o-rings, and also came away working properly. And the photo on the right shows her soaking the dump valve in the ultrasonic bath.

Next we turned our attention to regulators. Several people had  brought along Apeks regulators which they were going to take apart for my entertainment. Regulators are obviously a lot more complex than an inflator valve and you shouldn’t be taking them apart unless you  know what you’re doing. And as several people reminded me – certainly not at 40 metres, where Rita and I had inadvisedly attempted to fix a free flow several years ago!

First, was David’s first stage, an Apeks XTX 200. The disassembly took a bit longer, and particular care was needed taking out the membrane to make sure the metal part it sits on wasn’t scratched or damaged. Once it was apart, the metal and plastic all went into the vinegar to be ultrasonically cleaned. Putting it back together again is more fiddly, and it’s very important to pay attention to detail and get things in the right order. One of the problems I have is telling which o-ring to use, as some of them are quite a similar size. Since Catheryn also has an Apeks regulator, she was taking a careful look at everything. Andreas asked her to be careful “because we don’t want to damage it do we?”. To which she considerately replied “It’s David’s – I don’t care!” The Apeks first stage has a clear plastic cover, so you can put a label in showing the date of service, which sounds like a good idea.

Once it was all back together again, Andreas told David that he’d be so happy that he’d be buying him a beer all year. David pointed out that one beer for an entire year sounded like a good deal.

Ben and Catheryn also disassembled and reassembled their first stages, both Apekses – a T50 and another XTX200. Unfortunately Ben had to do his twice, as just after he’d got it back together again, he remembered that he’d wanted it as a stage regulator for Nitrox with more than 40% oxygen. Consequently he had to go back and use special grease to make sure it was oxygen clean.

Catheryn and David also serviced their second stages, although by then I’d gone for a curry, so I missed the final 3 hours. What a shame!

So at the end of the day we’d seen the innards of 3 types of inflator valves, 2 different Apeks first stages and a couple of different Apeks second stages. Plus an old Dive Alert that leaked when it is connected between the inflator hose and BCD inflator valve. I’d brought it along to see if we could fix it. Unfortunately  even the ultrasonic vinegar couldn’t save it. Still as David pointed out, I could carry it in my pocket and if I needed the loud audible signal that it provides, I could just hook it up on the surface where the leaking wouldn’t matter. After all, the signal still worked, as Andreas kindly demonstrated – leaving us all temporarily deaf.

All in all it was a very  interesting and useful day. Thanks in particular to Andreas and Gabi for arranging it all. And thanks to Catheryn for the photos.

On their website the BBC has got some footage of Japan’s secretive and rarely seen Akame fish. You can see it on the BBC website.

Scientists have found the fossilized remains of a 10 metre long shark in Kansas. They found a jawbone and huge tooth plates, which they believe it used to crush large shellfish like giant clams. The shark is called Ptychodus mortoni, and sounds as though it is the largest shellfish eating animal ever found.

They only have fragments of the jaw but have estimated that the whole jaw would have been 1 metre long, suggesting that the shark was around 10 metres long. It’s also difficult to tell what the shark would have looked like, but scientists are speculating that it would have been shaped like a modern-day nurse shark such as the one shown here. However it would have behaved more like a sluggish bottom-dweller.

Other remains have been found before, but none that suggested that the shark could grow this big.

The photos were taken from the BBC’s website, where you can read more.