Wreck Diving - Equipment
In addition to the diving equipment used for normal diving, there are several items that can be very useful in wreck diving. The first of these is a very sharp knife for cutting fishing line, nets and entanglements. A powerful torch allows detailed examination of all those intriguing nooks and crannie which most wrecks have in abundance.
A powerful torch is also good for locating your buddy in low visibility. In good visibility a high-power lamp will allow you to work slightly apart and still know where your buddy is.
Protective gloves are worthwhile even in warm waters - sharp metal plays havoc with hands or neoprene mittens. Many keen wreck divers wear a nylon overall over their suit to protect it. This is a canny item but failing to ensure it fits properly can result in snags and pockets of air becoming trapped inside it.
Some maverick divers carry tools clipped onto their harnesses and set off to undertake a bit of pioneering 'recovery work'. This usually results in detaching and recover souvenirs, such as portholes, from wrecks. However this practice is considered illegal by many as only the owner and those given expressed permission are allowed to do this.
If the wreck lies in an area subject to tidal streams, it is generally best to dive at slack water. In strong tidal streams or in poor visibility this is usually essential. The exception is when a number of divers are diving on a small wreck; the presence of a slight tidal stream can help by sweeping away the suspended matter stirred up by the previous divers.
Securing to the Wreck
If the wreck is not buoyed on your arrival, whatever method you use to locate it, you will be strongly advised to drop a buoyline in onto the wreck location area. For a small wreck this method may not be 100% on target (due to minor GPS fluctuations)and some prefer to drag a grapnel or anchor onto the wreck itself for precision. The first divers down to the wreck secure the line onto the wreck to prevent line drift and the last pair of divers should free the line. Some wrecks location and GPS coordinates are a closely guarded secret and may not have a buoyline (due to it being cut off!) or it may have a covert buoyline secured to the wreck. This is usually no different to a normal buoyline except that it is permanently submerged at 2-3 meters and serves as a final 'beacon' for divers 'in-the-know' who will be looking it as they approach the wreck site.
Descend an anchorline or shotline hand over hand. Divers have been swept away by letting go in a strong current. Some lines have a coloured marking to mark the end of the shotline, in low visibility this can be helpful.
It is useful to know the layout of the wreck, both to report on to other divers and to plan your route and dive profile. A compass can be helpful but a mass of metal may interfere with it. Direction of tidal stream and natural features can assist you in finding your bearings.
Movement on Wrecks
Most wrecks contain silt and mud, so you should fin just above the bottom to avoid stirring up too much sediment. When there is a tidal stream running, it is excellent practice to move to the lee of the wreck (the side shielding you from the current) or into its holds, out of the tidal flow. The water movement is then only a probem when you briefly move from one sheltered area to another or when you round the extremities of the wreck.
Do not forget to explore the seabed around a large wreck, becasue many unusual items may have fallen off. Masts lying on the seabed are usually worth a look, with interesting fittings to examine, often with lots of encrustations growing on them.
You must be cautious in your movements becasue wrecks contain a number of hazards. There are almost always sharp edges and projections - these can easily cut into hands and suits. In addition, large sections of wreckage, which appear quite solid and substantial, can be delicately poised and could damage and trap a diver if disturbed, Many wrecks are fished heavily by sport fishermen and consequently there is much lost fishing tackle with numerous sharp hooks just waiting snag the diver. Monofilament nylon fishing line is virtually invisible underwater and can easily entangle the diver. Wrecks often also snag the nets of commercial fishermen and these can pose quite a danger to the incautious, especially in low visibility. Obviously, a sharp knife that is easily accessible is essential for all wreck diving.
It is important in all ascents that you leave yourself enough time near the end of the dive to return to the shotline. This needs careful thought if the wreck you are on is a deep one. In good visibility this is usually not a problem, but in low visibility relocating it without a reel can become difficult and almost impossible if you are separated from the wreck. A flashing strobe or beacon light that emits light pulses can recify this potential hazard.
Allowing a minute or two for returning to the line in good conditions is good practice and a spare cylinder hanging at the 6 - 9 meter mark is handy for emergency decompression situations.
Divers will inevitably want to delve into a wreck that appeals to them, the enticing gloom and lure of the unknown is ever present. It can be complex to put into words the magnetism that can take a hold on you for wanting to explore within a wreck, it goes to the core of what it is to be a diver and push back another frontier within oneself.
Wrecks come in different shapes and sizes, some wrecks are so open and dispersed that a rookie diver would be safe drifting around it, others are so enclosed, dark and dangerous that even professional wreck divers may of perished exploring them. The marine encrusted tight hatches and doorways tend to be designed for sealing compartments off and can be quite small, a challenging obstacle for a fully equipped diver.
It is wise to try and remind the adventurous divers spirit to temper the need to go forth and roam freely with common sense and a realistic outlook when it comes to this aspect of wreck diving. If the surface is not directly accessible from a penetration point on a wreck then the necessary precautions should be taken and be aware that now you are entering a serious level of responsibility. Its a level of responsibility that can mean your very life is at stake if you don't proceed wisely. A diver roped to a buddy on stand-by at the wreck entry point is a lifeline in every sense of the word and should be considered a minimum. Within some wrecks collapsing structures, dead-end corridors that divers can only exit backwards and an almost sinister way that loss of direction occurs can be many hazards and challenges they entail.
The wreck-diving mavericks who learnt from experience may scoff at such things, afterall they may often pioneer into the unknown and self-rescue themselves sufficiently with no problems. It must be argued in their favour that a cool head and slick dive skill is a key factor in escaping from underwater dangers.