Who looks out for you when you have diving equipment problems? Diver does. In a new 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.
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The Scubapro folding knife mentioned - no longer in that company's catalogue. |
Can you please provide some clarification on how current legislation stands on the possession of the knife that you carry for the express purpose of diving. The two things that prompted this question were, firstly, a heated debate with one of our club members, and, secondly, the article in January's DIVER Tests featuring the Scubapro Foldable with an 8cm blade, which is, of course, a lock knife. When are you able to have a lock knife in your possession? Is there a maximum blade length?
Andy Roberts
An occasional member of the DIVER Tests team is a serving police officer in a tough part of London. I asked him to explain. He told me that under the Criminal Justice Act 1988, Section 139, it is OK to carry a knife with a blade of less than 7.5cm (3in) in length if it does not lock out in position.
It is an offence to carry a weapon with a fixed blade (or one that locks out in a fixed position) or one that is sharply pointed, unless it is either for use at work, you have lawful authority, reasonable excuse or other good reason. So diving knives can be said to be perfectly legal if used for that purpose.
If you are stopped by a police officer and found to be in possession of such a knife together with other diving equipment or, indeed, can prove that you are travelling back from the shop where you bought it, it is unlikely that an offence has been committed. Do not, however, go to football matches wearing your diving kit!
Most manufacturers selling a titanium regulator say that these are not suitable for use with nitrox. The Mares Planet Ti is a case in point. However, can you tell me why Mares sells a regulator, the MR16 (first stage), with a titanium high-pressure valve without the same "Not Suitable For Use With Nitrox" warning?
Guido Selling
You are quite correct that titanium and oxygen at high-pressure are unhappy bedfellows. Many Mares regulators have an SCS seating arrangement made of "titan" metal parts. These are a combination of chrome and nickel-plated brass, high-stress-resistant moulded brass, and stainless steel - but not titanium! The name Titan comes from the Latin for "strong" - as in Titanic!
Can you tell me why "deep-stop" seems to be the new buzz-word for decompression computers?
Georgina Mallory
Richard Pyle, a deep-diving icthyologist (or fish-collector), decided that if he divided his dive by depth and made definite stops in deep water during the ascent, he felt a lot better afterwards. He wrote a report about it and these stops became known as "Pyle stops".
Applying deep-stops by rigid formula is really formalising the commonly practised multi-level diving technique. In other words, instead of making a direct ascent from the bottom to the surface, the diver spends some time at intermediate depths.
Diving computers reveal that even if you are initially required to stop in the shallows (6m or 3m) while at the bottom, by stopping somewhat deeper, this shallow-water obligation can be shed before reaching that depth.
Some decompression experts say that deep stops per se are nothing more than "voodoo", because no real research has been carried out. However, many new computers allow the user to set this option. Deep-stops don't seem to do any harm, and if you are doing a square-profile dive they seem to be a positively good idea.
Two years ago I was in Barbados and went diving with my own kit. As soon as I turned on the tank, my octopus started leaking. Luckily guys on the boat had a spare, so we swapped over and all was well. I had it serviced when I got home and the guy said there was nothing wrong with it. I have just returned from another holiday to the same place and, you guessed it, the octopus leaked again!
The chaps at the dive centre reckon it's a problem with the first stage, but if that's the case, why didn't the primary leak? Also, one reckoned it was water in the first stage and another reckoned the intermediate pressure was set incorrectly.
When I got home, I connected it to my cylinder and, sure enough, it leaked, but when I swapped it with the octo from my pool kit, guess what, no leak! So do I assume that this is not a first-stage problem?
Martin
If you have an incorrect intermediate pressure setting or a worn valve seat in the first stage that allows that intermediate pressure to creep upwards, the build-up of pressure will cause the air to find a way out somewhere. It takes the route of least resistance, in this case your octopus. It might have gently inflated your BC or drysuit instead.
Usually the primary second stage is set to breathe the lightest, and this is where the leak will normally manifest itself. You probably have a valve seat engraved by the poppet from where the two have sat in contact unused for a long period. Get it serviced!
A double necklace helps keep the regulator configuration neat |
I have recently started to dive with independent twins after many years of diving with a single and a pony. I have my left-post regulator necklaced under my chin so that it comes over my right shoulder. My right-post regulator is on a 1.8m hose and I hog-loop this (DIR style) from under my right arm. However, I feel as if I have loads of hose everywhere, and switching regulators can be a chore if I'm winding in a DSMB or suchlike. Is there anything I can do to simplify things?
Noël Johnson
There are lots of different ways to rig hoses and we covered the subject recently. I tend to put one regulator in my mouth and have the second on the same double necklace, with both on regular length medium-pressure hoses.
I have an octopus from one loosely coiled on a long hose strapped under a bungee on my tank, with its second stage falling easily to my left hand.
This seems to be quite an emotive subject but I suggest that the best layout is the one that works for you.
I'm after a dive computer. I need one that works both on air and nitrox, can be used for decompression diving and can give me deco schedules for the ascent. I also need it to be capable of running at least two nitrox mixes, so that I can gas-switch and do accelerated deco, as well as being capable of working with all nitrox from 21% up to 100%. Which should I choose?
G Greenhill
You're in luck. Nearly every computer manufacturer can supply an example that meets your requirements, and there are a lot of new models coming onto the market, which might mean you can pick up an older one at a bargain price.
Take a look at the Apeks Quantum, Suunto Vytec, Suunto D9, Oceanic Atom, Dive-Rite Nitek 3 and the new Uwatec Smart Tec just for starters.
This Apeks tool keeps drysuit valves suitably tightened and keeps the water out - it is not for sale but dive shops use them |
Why is it that my drysuit always seems to leak through the inflation and dump valves?
Ian Noakes
The valves are most likely OK but they are probably not screwed into place properly! I often receive drysuits to review for the pages of this magazine and the valves are rarely more than hand-tight. A wet chest and arm ensue. I have recently received the specially designed tool from Apeks that allows me to do the job properly. It has made my life so much happier!
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We regret that questions cannot be answered on the telephone or, generally speaking, replied to individually.
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