Who looks out for you when you have diving equipment problems? Diver does. In our quarterly series, John Bantin fields your queries about gear, and calls on the suppliers for help where appropriate. If you have a problem with kit, let him know.
A long hose from an octopus can be draped round the neck - it's probably best not to wrap it round and round!
I was horrified to see in Where Do You Keep Your Octopus? (September) the picture of a diver with loops of hose running round his neck. The method illustrated will pull tight round the diver's throat, choking him.
Dr Iain Smith
A number of people have drawn attention to this and you're right, we goofed. After sifting through a pile of existing photographs of men in black suits with black hoses that were unclear, we set up a picture specially. My haste in the pursuit of clarity has resulted in a rig that may not have represented best practice, although it must be said that we have evidence of some divers rigging their hoses in this way.
It should have looked as in the picture on the right, with the hose routed in less of a wrap and more of a drape.
The hose runs down beside the BC from the back, then up from under the arm on the right of the diver. The end that leads to the second stage loops around the back of the diver's neck only ONCE from the left - not wrapped around the throat but using the neck to loop over as a rest for easy deployment.
As our feature concluded, whichever way you decide to rig your octopus, try it out in confined water with another diver breathing from it first.
My wife and I are going to Cocos. I know you're a fan of current hooks and the help they give in diving in fast currents without damaging the reef. Do you know of any dive shops that retail them rather than having to make my own?
Many liveaboard dive-boats have enterprising crew-members who make and sell these hooks. Sea Queen and Sea Spirit in the Maldives are an example. Few dive shops sell them, because few of their staff have any experience of such conditions and tend to sing the old song about damaging the reef, which is in fact the very thing they are designed to prevent you from doing.
I am not sure if they sell reef-hooks on the Cocos liveaboards but it doesn't take much to make one - just a large-jawed hook, a length of suitable gauge line or webbing and a karabiner.
For a suitable hook, browse in a good yacht-chandlers or try a proper ironmongers. I found a suitable length of steel rod with an eye turned in one end and then shaped it into a hook with the aid of a vice.
Other sources include a large gaffe or hook from an angling store, with the point filed off, of course.
I am looking for a tank that is very light yet can accept air to 300 bar of pressure. Do you know of any that might, for example, be made in carbon-fibre?
There seems little point in making a lightweight tank for use under water, as the displacement of the tank will require you simply to add lead elsewhere to make up for its additional buoyancy.
Already many divers who use heavier steel tanks in the UK have problems adjusting to the lighter aluminium tanks normally offered by dive centres in tropical destinations, and need to add some extra lead. The problem stems from the fact that water is so dense.
Is it true that helium mixes (trimix and heliox) cannot be pressurised to more than 200 bar?
This is a commonly offered reason for not filling tanks to 300 bar but its reason is based in practicality. David Tracy, gas-analysis expert, tells us: "Going beyond 200 bar is frequently done. In fact helium is supplied in J-cylinders at either 230 or 250 bar.
"However, helium has some peculiar characteristics which make people shy away from mixing trimix to the limit of 300 bar WP cylinders, because it's so hard to get the mix right. That's why gas-blenders usually suggest a lower final target pressure. It gives them a bit of space to play with and makes it easier for them to get the mix right."
The Suunto Vytec gas-integrated computer - how do you reset the transmitter?
Sometimes my Suunto Vytec gas-integrated computer is already switched on and refuses to pair with its transmitter when I turn my tank on just before I start the next dive. What can I do?
John Sinclair of Suunto Diving UK says: "There are two versions of the transmitter now in circulation but both are set the same way. From the Vytec Dive Mode surface display, press 'Time' twice to show the present stored code.
"Then press 'Plan' once to display the blinking 'Set C' and press 'Mode' once to erase the stored code and allow the new code to be set."
Examples of a DIN fitting and an A-clampin place.
I am about to buy my first regulator but am confused about DIN and A-clamp first-stage connections. What is the difference and which is best?
The International A-clamp does exactly that. It clamps around the cylinder and makes an air-tight seal in conjunction with a floating O-ring in the cylinder valve. There is no need to screw it up more than hand-tight, because the gas pressure of the tank, once it is turned on, holds it firmly in place.
The DIN fitting has its own internal captured O-ring and screws onto the fitting of the tank. It can be rated to either 250 or 300 bar maximum working pressure, depending on the length of the screw-threaded part.
The DIN valve is thought to be more secure (less likely to be displaced if you knock it accidentally) and generally less troublesome, and is now a firm favourite with European divers. Many dive centres now use DIN-valve tanks with an A-clamp converter in place if needed, but worldwide there are more tank valves suitable only for use with A-clamps in circulation. In this case DIN regulators need their own adapter.
I want to connect the TTL flash I used with my old analogue camera to my new digital camera and get automatic TTL exposures. How can that be done?
The simple answer could have been that you cannot, but now, if you have an Olympus digital camera or a new Canon 300D and a suitable flashgun, I am told that a company in Germany makes the special gizmo you need.
The OLY TTL Technic works in conjunction with all Sea & Sea, the Ikelite DS125 and the Inon Z220 flashguns and interfaces primarily with Olympus cameras. German speakers can check out www.mike-dive.de
I am looking to buy a suit suitable for use in colder waters such as places in England, and I don't know whether to buy a semi-dry or a drysuit. I'm 13 years old and still growing and will grow out of whatever I buy.
For diving in the UK, buy a drysuit but be aware that you need to be taught how to use it. Accidents can be fatal. Some far-sighted suit manufacturers are already addressing this problem when it comes to wetsuits and semi-dry suits and can now provide them in quite small sizes.
The growing problem is something with which all of us have had to cope at some time. As more young people take up diving, a thriving secondhand suit market in smaller sizes will gradually evolve.
Alas, you are in near the beginning, so it looks as if it's going to be expensive. What does your dad think?
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