Diving Thoughts

In April a crane driver from a diamond mining company spotted coins at a site that had been drained for diamond mining. These turned out to be from a shipwreck, which looks as though it might be a 16th century Portuguese trading ship. A team of archaeologists is now working around the clock to excavate it.

So far they have found gold and silver coins, cannonballs, copper ingots, ivory navigation instruments, pewter plates, pieces of ceramics, and parts of the wooden hull. The copper ingots carry a trident seal that was used by the Fugger family, an influential German banking and merchant family who supplied goods to the Portuguese crown. The cargo comes from Africa, Asia and Europe, showing how extensive trade networks were in the 1500s.

The mining operation works by building a sea-wall and then draining the area and dredging the dry seabed. Pumps are needed to stop the sea reclaiming the  area, but they cost thousands of dollars a week to operate. The excavation is due to go on until mid-October.

You can get the full story from the BBC, from where the above pictures comes.

September’s Dive Magazine as usual has a column in it by Monty Halls, a television presenter. I always enjoy his columns in the magazine as he has a good sense of humour. This month’s column continues with our hero living in the bothy that he rebuilt on the west coast of Scotland for a BBC series. He is heading off to visit a massive grey seal colony that is nearby, but he had to read up on grey seals first so he had something intelligent to say to the camera. His point was that he enjoyed the encounter with the seals so much more because he made the effort to read up on them beforehand.

I think he’s got a very good point. When I think about the dives I’ve enjoyed the most, they tend to be the ones where I know and understand what I’m seeing. Whether that’s the interaction between various marine creatures, such as shrimp and goby pairings, cleaner wrasse or shrimps and their customers, or whether it’s the layout of a particular wreck. For wrecks in particular I find a dive far more interesting if I know the historical context of whatever it is I’m diving on. As an example, in Chuuk several years ago I was diving the Emily Flying Boat. It’s not a particularly big wreck compared the ships that are there, but its history made it interesting. The Commanding Officer of the Fourth Fleet, his Chief of Staff and other senior Japanese Naval Officers, were returning from meetings in Palau. While on the way back to Truk, the plane was ambushed by US fighters and repeatedly attacked. Despite heavy damage and casualties, the pilot managed to escape the fighters and return to Chuuk. Unfortunately, the aircraft was so badly damaged that the pilot lost control while attempting to land in the lagoon and the aircraft crashed and sank. The pilot survived and was decorated for his actions. The Admiral and his Chief of Staff also survived. Knowing that made the dive a lot more interesting.

I went to Chuuk as part of a Club trip and we were diving from 2 tenders with 8-10 divers on each. I think the people on our boat enjoyed the trip a lot more and I suspect it was because we had all been reading up on the wrecks. So we knew what they were, how they’d sunk, what was on them, and we knew in advance what we wanted to see.  In fact I would take down laminated sheets describing the wrecks, along with schematics, which meant that we could orient ourselves on the dive and remind ourselves what it was we wanted to see. But as an added bonus, the morning dives involved quite long safety stops hanging on a line, which was a great opportunity to read up on the  rest of the wrecks we were going to be diving that day.

So whatever your interest, if you spend some time reading up on it in advance, you’ll enjoy your dives a lot more.

The Hong Kong Standard for Tuesday 23 September has an article suggesting that tour groups are scaring the white dolphins that we get in Hong Kong waters. The Agriculture, Fisheries and Conservation Department (AFCD) feel that some of the tour groups are being too aggressive and getting too close to the dolphins, which may be driving them away.

There are 3 main types of tour groups:

• Professional dolphin watching tours
• General city tours which include dolphin viewing and are usually organised by local travel agents
• Individual boat owners leading groups of people out on their own

The third group are seen as the biggest problem as they are more likely to race towards dolphins when they have been sighted.  It is also more commen for groups of small boats to “ambush” the dolphins, causing more stress.  All tour groups are encouraged to follow common guidelines such as keeping a minimum distance and not feeding the dolphins.

According to studies and observations over the years, AFCD have found that dolphins surface less when there are boats in the vicinity. Considering what has happened to 2 divers in Hong Kong over the last couple of years, you can hardly blame them. (Some information on the most recent incident here and here).

I was once lucky enough to do a trip out with one of the people responsible for doing regular counts of the dolphins, and it was a really good day out. It was the first time I’d seen them close up and it’s something I won’t forget in a hurry. But it’s a difficult balance between giving people the chance to see one of our rare marine creatures and learning more about them, and putting too much stress on them.  AFCD need to make sure the guidelines they have in place are working and are being observed, and tour operators need to be very careful to keep to these guidelines. Hopefully tourists will report any concerns or issues that may come up on their tours.

My favourite dive operator in Malapascua has added another string to their bow, as Thresher Shark Divers is the first (and, at the time of writing, only) technical diving facility on Malapascua. They are able to offer technical diving to certified technical divers, as well as IANTD courses. They also hope to introduce PADI DSAT Courses soon.

Malapascua is a lovely little island just north of Cebu, which is best known as a place where you have a great chance of seeing Thresher Sharks. They come up to several cleaning stations on Monad Shoals, and are fantastic to see. Threshers have very long tails, but a surprisingly stocky body, along with lovely big eyes. In addition, you often get Manta Rays, Devil Rays, and the macro life is very good too. So if you fancy some diving down in the Philippines, it’s well worth considering.

Thresher Shark Divers is  run by a British couple, Trevor and Andrea, who are both very friendly and very helpful, as are all their staff. I have enjoyed 2 great trips with them and hope to get back very soon.

BSAC have recently launched a workshop on buoyancy. Increased emphasis on how important buoyancy is can only be a good thing, as once you’ve sorted that out, so many other things become so much easier. Diving becomes more enjoyable, more comfortable, and, above all, safer.  You’re less likely to stir the silt up inside a wreck, and you’re less likely to kick lumps out of the reef with your fins.  It seems to be one of the basic skills which is most difficult to master. Some people are naturals, but for the rest of us I’ve always felt that there is no real substitute for practice.

So is this workshop a substitute for practice? Well, I can’t say for sure as I’ve not participated in one. But it sounds as though it directs practice to where it gives the best results. It consists of:

• A 2 hour theory lesson covering correct weighting, position in the water, trim, breathing and gear configuration
• Minimum of 2 open water dives which cover a variety of skills including moving one metre from the bottom without stirring it up, horizontal positioning without finning, fine-tuning buoyancy control through breathing alone

To encourage a bit of healthy competition, there is also a buoyancy challenge with the following grades for staying within certain limits for 3 minutes:

• Bronze: + or – 2 metres
• Silver: + or – 1 metre
• Gold: + or – 0.5 metre
• Black: + or – 0.3 metre

Anything that improves buoyancy can only be a good thing, but I still think lots of practice are still the key.

You can read more about it from BSAC’s website.

Here’s some great photos on the BBC website. Well worth a look.

While I have been critical of the Hong Kong fishing industry and the fact that fishing in Hong Kong is currently not sustainable, I am not completely dismissive of the important part that the fishing community has played in Hong Kong’s history. So it’s good to see from the SCMP that a working model of a traditional 1960′s fishing trawler has found a home at the Maritime Museum. This type of junk used to trawl in Hong Kong and Macau waters, but has now disappeared entirely.

The model was built from memory in the 1990s by a former Aberdeen fisherman, Ng Sap chat, and he has now kindly donated it to the Hong Kong Maritime Museum at Murray House in Stanley. Thanks to the SCMP for the above photo. If you are a subscriber you can read their article on their website. (Or if you read this quickly enough, you can pop out and buy the paper!)

Not a particularly new story, but thanks to Alex G. for pointing it out to me. Kirill Larin, an assistant professor at the University of Houston in Texas, is attempting to produce a device that could routinely be used on people moving from a high pressure to a low pressure environment, to try and identify the onset of decompression sickness (DCS). His research is in optical coherence tomography (OCT), which uses lasers to make high resolution images of biological tissues.

For any non-divers who have stumbled across this article and haven’t immediately abandoned it for something more interesting, DCS happens when gas such as nitrogen which has been dissolved in body tissues is released and forms bubbles. From a diving perspective, as you descend, the pressure increases which forces more gas to dissolve in the various tissues in your body. As you ascend the surrounding pressure reduces and the gas is released but it tends to group together into microbubbles. Ideally these are expelled through the normal breathing process, but if the pressure reduction happens too quickly then larger bubbles can form which can start to cause problems such as joint pain, neurological problems, skin rashes, burning chest pain. Ultrasound has been used to study these microbubbles, but has a resolution of 80-100 microns, whereas OCT promises images with a resolution of only 2-10 microns, which will detect much smaller microbubbles in the bloodstream and could help diagnose DCS early enough that it can be treated before becoming symptomatic.

The reasearchers’ goal is to produce a portable device that can detect problems in seconds just by shining a light on a person’s skin.

There is an article Popular Mechanics’s website, which mentions possible beneficiaries as divers, but also astronauts and high altitude pilots once they land. Although a pilot landing would face increasing pressure as they descend, not decreasing pressure, so should not be susceptible to DCS unless they’re are other factors involved such as a space capsule or a plane or a flight suit being pressurised to more than 1 bar.

Anyway it will be interesting to see if it is possible to produce a device that is easy to use, portable and cheap enough to start appearing on dive boats. I’m not holding my breath – but then as a diver we’re always taught not to hold our breath!

In what could be good news for divers, the SCMP is reporting that a consultation paper from the Food and Health Bureau’s Committee on Sustainable Fisheries is due to be released next week, which will suggest outlawing trawling in Hong Kong. This is an attempt to make the fishing industry more economically and ecologically sustainable. Proposals also include the Government buying out trawlers and offering retraining and financial help to fishermen who are affected.

According to the article, there are around 1200 trawlers in Hong Kong, of which 550 operate in Hong Kong waters. Hong Kong is one of the few places to allow trawling so far inshore and this is a particular problem because of the damage they do to the seabed and because they also catch immature fish which makes it very difficult to replenish fish stocks. Many of us who have dived in Hong Kong have seen the results of such trawling, where vast swathes of the seabed have been scoured clean of any marine life or features of interest.  To make matters worse Hong Kong waters are spawning and nursery grounds. So a ban should help support fish stocks and help the environment to recover. Good news for divers and also sports fishermen who have proliferated in Hong Kong over the past 10 years. These are the keen, dedicated people who are dropped off on barren rocks throughout Hong Kong every weekend, where they spend hours and hours avoiding the wife and kids!

So a ban would be in the interests of almost everyone except the fishermen who are affected. Obviously a scheme to help them will be necessary. The SCMP estimates that it would cost HKD 385 million to buy up the 550 trawlers that operate in Hong Kong waters. This does not include costs for retraining or compensation for loss of business.

Given the traditional power of the fishing lobby, I suspect it won’t happen in the short term, but it is good to see such a proposal, since a recent paper by the Committee on Sustainable Fisheries estimates that Hong Kong waters are overfished by 30 per cent.

The above cartoon is from Harry in SCMP, and if you are a subscriber, you can read the complete SCMP article.

Opposed to shark finning? How far are you prepared to go to protest? Alice Newstead, a UK-based artist, has hung herself up from shark fishing hooks in a London cosmetics store to highlight the use of shark products in food and cosmetics. Ms Newstead used to be a sales assistant at Lush, the Regent’s Street cosmetic shop where she was hanging up in the window, but left in June to work full time as an artist.

She apparently said “I am doing this because the demand for shark fin soup and other shark products is wiping out the shark population”.

So here is an artist who is both suffering for her art, and for sharks. You have to admire her courage, and dedication. Of course as an engineer, I have to say that it’s nice to see we’ve found a good use for artists at last!

The story is on the Telegraph’s website, which is where the above photo comes from.

Ambient Pressure Diving have found problems with some hoses because connector fittings have not been properly crimped. In the photo to the left (from Divernet), the top hose has been crimped correctly and has eight visible flat parts on the metal collar. The one below has not, and the collar is smooth and round.

Products which may have these hoses include low-pressure hoses used on Inspiration, Evolution and Evolution+ rebreathers; the Buddy Blast Hose (air horn end only); second stage regulator hose (second stage end only); and gas connection system (second stage/ADV end only).

There are more details on Divernet.

It shows just how little we know about marine life and biodiversity when a new species is discovered in an area as well studied as the Red Sea. This time it’s a giant clam, Tridacna costata. Despite being called a giant clam, it’s actually only medium-sized, growing up to 40 cm in length and weighing up to 2kg. They seem to live in shallow waters and have a relatively short breeding season which coincides with the seasonal plankton bloom. As most condom users may not realise, “costatus” in latin means “ribbed”, which refers to a zig-zag outline to its shell.

Fossil specimens show that around 125,000 years ago this species made up around 80% of the region’s giant clams, but now they may be critically endangered. By a strange coincidence (or not), humans are believed to have appeared in the Red Sea area, and a large, abundant, easily accessible food source, such as these clams, would have been an ideal food source. It is quite possible that the dramatic decline in their population was an early example of over-exploitation of a marine resource by people. But sadly not the last example, what with shark-finning decimating shark populations.

Photograph above is from the BBC.  The research is presented in the Current Biology journal.