1. Contents Gauges: They can let you down.

Recently I had a problem with my contents gauge, although at the time I didn't realise it. I guess I should have, but in my defence, neither did anyone else on the trip, & there were some pretty experienced divers around. The gauge read 320 bar in my 232 bar cylinder! Get in the water I was told, breathe it down a bit! Luckily I was diving on a twin set, because I ran out of air on that particular cylinder whilst pausing at a 9m stop, even though the gauge read 100 bar. It took a while to register. I felt the reg start to become hard to breathe & knew what the problem was - I had emptied a cylinder in the comfort of my own home to see what it felt like to run out, just in case it ever happened for real. Well, there I was, the gauge read 100 bar, yet nothing was coming out. My brain could not cope! I swapped regs & finished the dive. On further investigation, it became clear that the gauge was reading 100 bar too high - even when disconnected! It has now been consigned to the rubbish bin! So, hint number 1: If your gauge reads something silly, try another just in case it is the reg that is at fault. Hint Number 2: When changing gauges, there is a small pillar inside the hose that half fits in the hose, & half in the gauge. This has an O-Ring at each end. It should be thoroughly greased with silicon grease & also needs to be the correct sort. Some are straight, others have a shoulder to prevent them going too far into the gauge - they are NOT interchangeable! The bad news is that they seem to be okay if tested on low pressure, but can fail badly on full pressure. Make sure you have the correct one fitted & tested before showing up at a dive site.

2. Stuck inflators on a jacket & how to change them.

Of course, no inflator worth its salt is going to fail during the buddy checks, it is only ever going to fail during a dive, & normally at the worst possible time i.e. either during the deepest part of your dive, or at a deco stop. If you are lucky, it will fail closed so you can't inflate the jacket/wing. Also if you are lucky, you will be wearing a dry suit & can deal with the problem by using your dry suit as the sole form of buoyancy control - a bit nasty on the surface, but either close the dump, or keep your arm down, or fin like buggery! If it fails open, i.e. air is always going in, then abort the dive immediately! You will know it is happening because you will keep floating upwards, despite dumping for all you are worth! Keep the inflator dumping air & get up as fast (but as safely) as possible. In my case, the button jammed in the open position, so air was going into the wing - just enough to lift me, but not enough so it was obvious! It took a while to realise. Changing the controls is simple. Remove the tie-wrap from the joint between the concentina pipe & the control mechanism. Push the pipe upwards which will expose a small pillar running across the tube. This holds the wire that attaches to the dump itself. It needs to be pulled/pushed out. Once done, the control mechanism can be removed. Sometimes the buttons just need greasing, other times, the spring is broken or damaged & the whole unit needs replacing. Most manufacturers will sell you a new one. As they say in all good car manuals, replacement is the reversal of removal, & so it is. Slip the pillar back through the locating hole, through the dump wire & into the hole on the far side. Slip the tube over the top. Before adding the tie-wrap, ensure all is well by trying the unit, but remember, air will leak! Finally, replace the tie-wrap, pull it good & tight & perform a final test to ensure the jacket/wing inflates & there are no leaks.

3. Greasing O-rings to prevent leakage.

Whenever you change an O-Ring, with the possible exception of the main one in the cylinder, you should always grease it with Silicon grease. This helps with the sealing no end & can make the difference between a good seal & a leaky seal. Also, if you have a small leak, make sure the O-ring is properly greased before investing time & effort changing it. Don't go mad with the grease, a small amount spread round with a finger is plenty - it should just smear the rubber. Silicon grease is difficult to get hold of in quantities (it seems). Dive shops will sell you a small tub for a lot of money - a 2p sized container less than a centimetre thick costs £3-£4, but will last forever, unless you have a waterproof camera housing that requires regreasing for every dive that is - but that's another story.

4. Adding an elastic loop to timers, computers, compasses etc to prevent loss if the strap breaks.

Computers are expensive, timers are expensive, compasses are quite cheap (for dive kit), but no-one wants to lose one. Of course, when the strap finally breaks, & these rubbery ones will do sooner or later. I have an Aladdin Dive Computer & am on my second strap, my compass strap has been about to break for about six months now - it *will* go one day. My tip for preventing loss is simple. Get a piece of elastic about 0.5m long. Tie a tight knot onto the strap of the computer with one end, & a large slip knot onto the other (fishermans, hangmans etc). Now when strapping your computer on your wrist, slip the elastic onto your arm & pull it (reasonably) tight. Strap the computer on as normal. If the strap ever breaks, the day will be saved by the elastic! Simple, costs about 1p to make, but could save tens or even hundreds of pounds.

5. Cylinders & how to carry them

Cylinders are delicate - make no mistake! Sure they are made of hard metal & if you drop one on your toe it's gonna hurt your toe more than the cylinder, but, they are delicate! Time & time again I see people take a cylinder by the valve & throw it over their shoulder & march off to wherever they are going. That cylinder is now between 5' & 6' off the ground. If you drop it & you are lucky, it will land boot side down & you will spin round fast enough to stop it falling further. Of course, most of us are just not that lucky & we will drop it forwards or it will do a half-somersault & land valve side down. This is the worst thing that can happen! The valve will most probably shear, causing whatever air inside your cylinder to make a dash for freedom. Now Isaac Newton, who, as far as I know, never went Scuba Diving, had some pretty flash ideas on this subject! Basically what he said was that if air is rushing out of your cylinder because you are stupid enough to drop it on its valve, then the cylinder is going to do its best to rush off in the opposite direction & take out whatever gets in its way! Also he said that the valve will probably side with the air & launch itself at someone at very high speed. Somebody else, whose name I know not, probably Boyle or Charles came up with some pretty flash laws of thermodynamics & went on to invent anti-perspirant sprays reckoned that Pressure multiplied by Volume divided by Temperature is always constant. So what you say, well, the so-what is that the temperature of the air inside your cylinder will eventually be the same as the air around you, so P x V is now constant. If the pressure suddenly drops because your valve has parted company with the cylinder, & in a cylinder this would be about 50 times i.e. from 50 bar inside to 1 bar outside, then the air has no choice but to become 50 times bigger, not only that, but as the air expands, it cools, so the poor unfortunate that is anywhere near you when you do this, will be either hit by a cylinder, a valve or expanding, cooling air, & if you are lucky, you will only be hit by his (or her) fist in the gob for being such a knob-end. So, take my advice, either, get a trolley & carry them, which I can assure you is the easiest way, or, if you must prove your manhood, carry them by the valve, boot end downwards - or invest in a carrying handle & carry them low to the ground. That way, if you do drop them, they will only fall a short distance & not do anyone any harm, except you of course, because they will land on your foot, but that is too bad.

6. Kit Checks

Whenever I go diving, I always assemble my kit a couple of days beforehand, just to ensure that everything still works, there are no leaks & I am not going to be surprised on the day. If I am hiring club kit, I will doubly check it as I do not know the history - maybe the last person dragged the regulator across the beach on his way to the car - & yes, I HAVE seen that first hand! Also, the water will wait! If, for some reason you are given different kit at the last minute, check to ensure it is compatible. On a recent night dive, my buddy was given a cylinder to use which was A-clamp fitting, his kit was DIN! Luckily I had a spare set in my car so we were okay. Never leave kit checks to the night before - what if you need something? Never, ever leave kit checks to the actual day, there is nothing worse than kitting up, getting into a dry suit then sitting around for an hour while your buddy rebuilds his kit - yep, done that too! On the same subject, always carry a spares kit. Mine contains lots of useful stuff - Allen Keys, make sure you have enough for everything, including the cylinder insert, an adjustable spanner, spare mask strap, spare fin strap, silicon grease, spare first-stage blanks, tie-wraps, a swiss army knife, some cash!, a spare set of O-rings for *all* fittings, not just the cylinder. If I am diving on a twin-set I have a full set of spare hoses & regulators in case either something fails, or, I need to reconfigure to a single. After a diving day, I will hang my kit to dry, then, before putting it away, have a good look at it all, are all the straps tight on the wing?, is their any damage to the regulators or first stage?, are there any nicks or damage to any straps? Finally, I will wax my dry-suit zip with a candle - a damn sight cheaper than 'proper' diving wax & just as good.

7. Get your Cylinders tested

Cylinders need to be tested, that's a fact. Depending upon how old your cylinder is, depends upon whether it needs a visual or a hydraulic test or both. The last test date is stamped on the top of the cylinder somewhere as a month followed by a year, e.g. 07/2004 would be July 2004. So what you say, I know all that. Well, the so what is this; Did you know that if you allow your cylinder to go out of test, then the test house are perfectly within their rights to perform a complete test & charge accordingly i.e. twice as much! So, this tip is: Make sure your cylinder gets tested in good time otherwise you may find your bill is more than you expected.

8. Grease your O-Rings to make them last longer

Everyone has a selection of O-rings in their toolbox just in case one happens to go. Did you know that they dry out & eventually fail to make a good seal? Maybe you have recently changed an O-ring & then wondered why you had to change it again. To make them last longer, pop a bit of silicone grease into the bag with them, they will last a lot longer.

9. Rigging a Pony Cylinder

Easiest way is to check out this website:Rigging a Pony Cylinder