JackKit

Jack Ingle is the BSACs Technical Diving Adviser. He is a BSAC National Instructor, an IANTD Technical Instructor, a TDI Tri-mix instructor and co-author of NSAC nitrox courses.
SHEDDING WEIGHT WITH A TWINSET
I have started to use twin 12 litre cylinders with a 7 litre decompression stage cylinder. I am finding this set-up very heavy and I have to put lots of air in my drysuit and wing. Is there anything I can do to make things easier
Steve Graham

I run technical diving courses all the time and this is a regular problem for divers new to twinsets and stage cylinders. I know it sounds obvious, but remember to remove enough weight from your weightbelt.
Diving twin 12 litre cylinders I dont need a weightbelt at all, even when wearing a neoprene DUI drysuit. However, many divers feel they need weights even after adding more equipment to their configuration.
You should be able to control your buoyancy on one source. If you are a wetsuit diver, this will be the BC or wing. However, as a drysuit diver I use only my suit for buoyancy; the wing is a redundant source in case the suit fails.
If you use your suit only for the comfort factor and would feel too uncomfortable with more gas in it, and are wearing weights as well, you can afford to remove some or all of that lead to allow the suit to cope comfortably with buoyancy control.
The simplest way is to carry out a full buoyancy check. Find a sheltered-water site and take all your equipment to the waters edge, including twinset, stage cylinders and weights. Bleed each cylinder down to 10 bar to give you the lightest weight they can reach without being empty.
Before putting your twinset on, remove all the air from your wing or BC. This may mean sucking it out (dont do this regularly, or you risk a lung infection).
Put your twinset on, inflate your drysuit and enter the water without any weights or stage cylinder. Float for five minutes at the surface, relaxing your breathing rate. You dont want your lungs acting like over-inflated balloons and causing even more buoyancy problems.
Then open the suit valve. Depending on the type of drysuit, membrane or neoprene, you may or may not sink. If you sink, you dont need any more weight and can compensate for the negative buoyancy under water by adding air to your drysuit.
If you dont sink, inflate the suit again and ask someone to pass the stage cylinder to you before running through the process again. You will normally become negatively buoyant and sink. If you have a very thick drysuit, you may need to repeat the process by adding weight, but add only 1kg at each attempt to find out the minimum amount of weight needed.
It takes time but once done your buoyancy is sorted out forever - or until you make further equipment changes. Remember, if you add equipment you can take weight off but the reverse also applies.
How not to bash cylinder valves
Nearly 80% of our dives involve penetration. I am very cautious when entering any of our targets but sometimes cannot help banging my cylinder, which worries me as I have heard of people having hoses cut from their first stages. We have been thinking about protecting our first stages with halo protectors similar to the Custom Divers ones, but want to make our own. Do any other companies make such devices The systems are to fit both DIN and A-clamp first stages, most of which are Poseidon.
Jethro Belman

I like your attitude of caution when it comes to penetration. Most wrecks are slowly rotting and collapsing, and you dont want to be inside with the danger of your equipment scraping and bumping into the wreck and causing a collapse.
There are various types of cages that sit over the cylinder valves and first stages, from L-shaped single-cylinder brackets to the full-blown cage that covers both sets of valves, otherwise known as scaffolding.
Originally these were meant to be used with inverted cylinders to make access to the on/off valves easier, allowing the set to be rested on the ground without damaging the valves.
You can see many options displayed at the Dive Shows (the next one is in London at the start of March).
You talk about A-clamps on first stages, and if you knock one of these, you will dislodge the O-ring and have a massive flow from the cylinder. I would suggest you try to use DIN fittings on all your cylinders to avoid this problem.
Hoses can easily be snagged and cut when caught on wreckage. Try to route your hoses downwards to avoid them sticking out at the sides or above your head. Bring all hoses under your arms rather than over your shoulders to protect them, though this may mean having to buy longer hoses.
Its also worth participating in an Extended Range Diving course to teach you about equipment configuration and penetration techniques. Above all, keep practising those buoyancy skills to make sure you dont bump into anything.
The safest ways of filling a DSMB
I have been using a delayed SMB for some time and always deploy it using my octopus. I normally dive in Greece where the water temperature rarely falls below 10ÂC and this technique always works. However it seems that it is not a good idea to purge your regulator in very cold water, as it might freeze. Are there alternative ways of deploying an SMB other than using the octopus
Ooannis Giannikos
While training for my Sports Diver qualification I came across a PADI diver being trained to use an DSMB. We had been told to hold the reel in the left hand, fill the DSMB from the exhaust outlet of our regulator and then release when it started to pull. The PADI diver was told to sit on the platform, unreel and drop 5m of line using the weight of the clip, then drop his reel to retrieve the clip, fix the clip to the DSMB, fill the bag and slowly feed the line through his fingers when the it was partially filled. Can you shed light on right and wrong ways of deploying a DSMB I feel the second method is extremely dangerous.
Anonymous

If you are sending a DSMB from the seabed, tie the reel to something so that if it jams it wont drag you to the surface or disappear as it ascends without you.
Make sure you have enough line to allow for your depth, and never attach the reel to yourself, as a jam would take you up like a rocket. Some divers use quick-release clips to avoid this, but I wouldnt attach a DSMB to myself. Another method is to ascend to about 20m in midwater to send the bag up. This calls for good buoyancy skills while operating the reel or drop-line and inflating the bag. I use this method and its easy enough, but many divers get into trouble while shooting bags through not having practised enough.
You can use your primary second stage to inflate the bag but you wont be breathing, which just adds to your general task-loading and stress levels.
Using your alternative second stage makes the job far less stressful. Purge the device slowly, as this reduces the chances of a free-flow and allows more control of the SMB. Inflate too fast and the SMB will be snatched out of your hand and you could lose it and the reel.
When using a second stage, keep it well away from the lines and fittings of the DSMB to prevent entanglement. But always avoid excess line hanging from the reel or drop-line, as it will inevitably get wrapped around you, your buddy or your equipment. Accidents with DSMBs usually occur because of entanglement.
Another good tool is a purpose-made inflator hose with a narrow nozzle for easy insertion into the SMB. Inflate by pressing a button or bending a rubber hose. I have also seen divers use the exhaust valve on their regulator, and this works too. Place the SMB above the valve and the gas enters the bag as you exhale.
I prefer to use the type of DSMB which has a small air cylinder attached. I dont have to mess around with regulators or inflator hoses, but simply attach my reel to the SMB, and with one hand flick open the cylinder valve. Its slightly bulkier than the standard DSMB but far easier to use.
Remember to charge the cylinder before the dive, though you can always revert to another air source if necessary. AP Valves makes a very good version. Others work with a small CO2 cylinder, but these cannot be recharged.