Suits, Boots & Gloves

ROALD Amundsen wanted to go to the South Pole so he looked at the sort of clothes worn by Eskimos and copied them. Captain Scott went out and bought himself some thick sweaters. The rest is history.
It is important to wear the right gear for the job in hand. Because we never dive in water warmer than our own body temperature, heat is always conducted away from the body underwater - and water conducts heat more than 25 times more efficiently than air. If you do get cold, it could interfere with your concentration and lead you to make mistakes.
Divers in hot countries must balance the warmth needed underwater with the air temperature at the surface. In cooler places, you must consider the effect of water evaporating from a suit during chilly boat rides.
As we lose most of our heat from our heads, it makes sense to wear a hood. However, this restricts head movement and impairs hearing at the surface, so in practice the head is the last part of the body a diver tends to cover.
A suit also offers some protection from the unkind abrasions that divers might encounter underwater. Stinging hydroids, jellyfish, man-eating plankton, surfaces of metal encrusted with marine growth, and even the chafing of straps from the diver's own equipment can spoil an unprotected diver's day. Even in tropical countries, only the most casual diver enters the water without a suit, as loss of heat leads to increased air consumption and shortened dive times.
In their most minimalist guise, suits are dive skins made from Lycra. Some dive skins are reinforced with high-tech materials to give them greater insulation. They all tend to reveal every defect of a diver's body, so if your body resembles a bag full of bolts and blancmange, a dive skin may not be the wisest choice.
The next level of insulation is provided by the lightweight neoprene wetsuit. These come in 2mm or 3mm thickness and can either cover the whole body or leave the arms and legs exposed, "shortie-style". Shorties are not ideal in the sea but are often used for pool training. The 5mm one-piece suit, usually with a zip up the back, is popular with divers in warmer climes.
A wetsuit gets its insulation from the tiny integral bubbles of gas that form within the material. An additional film of water between the material and the diver's skin adds to this insulation, but for this to work it is essential that the suit is well-fitting. Any water flushing in and out of a poorly fitting suit will carry heat with it.
One way to stop this flushing effect is to add smooth skin seals at the ankles, cuffs and along the inner edges of zips. Suits with these features are known as "semi-dry suits" because they tend to get damp rather than wet.
For more effective thermal insulation, as needed in British waters in mid-summer or the Red Sea in winter, semi-dry suits come in a heavier-weight 7mm material. You can choose between a one-piece with an additional layer for the torso, or a long-john and jacket, which gives a total thickness of 14mm over the torso and usually has a hood attached. Keep in mind that the effect of pressure at depth makes neoprene more compressed and its insulation less effective.
Some suits have a titanium fleck in the material for added insulation. Others have a thermo-metal lining that takes heat from the body and releases it back during the latter stages of the dive. Some suits have both.
Semi-dry suit seals tend to be made of neoprene, which can make the suit a little awkward to put on. Some manufacturers like Mares and Cressi-Sub have recently adopted more flexible double latex seals with nylon covering flaps to help solve the problem.
Whatever wet- or semi-dry suit you use, you will normally need to wear boots. It is best to avoid any which have seams along the top of the foot, as these will cause sores from the action of finning.
Drysuits keep the water away from the diver's body entirely, so give the most efficient thermal insulation. They are made in a variety of materials, all with fixed watertight boots and tight seals of latex or neoprene at the neck and cuffs. Neoprene is more hard-wearing but latex makes for a better seal and can be easily replaced when the time comes.
The first drysuits were made from rubber and had as much style as a dustbin liner. Then came made-to-measure drysuits in extra-thick neoprene. These, if punctured, retain most of their insulating properties. They are quite restricting and suffer dramatic buoyancy changes as the diver goes deeper, because there is so much neoprene to compress. Divers in traditional neoprene suits are often seen wearing inordinate amounts of lead to overcome the extra buoyancy at the surface.
With the advent of trilaminates, which have a layer of butyl rubber sandwiched between two hard wearing synthetics, drysuit design took another step forward. Trilaminate membrane suits come in a full spectrum of colours, and can be made from a large number of sections which give them an attractive tailored look. The joins can be stitched or glued, then taped - in the case of the Gates suit, this tape can be vulcanised to stop leaks.
Membrane suits provide no thermal insulation if worn alone. It is best to use a proper undersuit but some divers prefer to wear the clothes they arrive at the dive site in. Undersuits bearing the "Thinsulate" label have a high degree of insulation and are wind-proof if worn between dives. Other suits have a Teflon-derived outer layer which makes it easier to slip into the drysuit. Be careful to select one that will not impede the exodus of air from the dump valve during the ascent.
DUI, a Californian company, makes its top-of-the-range suit from neoprene and then crushes the gas out of it to make a particularly hard- wearing suit.
Northern Diver, a company that captured a large part of the traditional neoprene drysuit market, makes membrane suits from pre-compressed neoprene in a choice of thicknesses.
Typhoon used to make a suit with a lightweight rubberised cloth, but it tended to leak. The company, under new management, has now replaced the material with a more suitable, heavier grade.
Drysuits are fed with air via a direct-feed hose to prevent painful squeeze at depth. Either constant volume valves are fitted at the shoulder or a diver can opt for a simple cuff dump, which releases air as soon as the diver raises his arm above his body. The cuff dump is no good for photographers because it will release air every time the camera is raised to the eye.
You must be happy with the positioning of the valves and make sure they can be operated in conjunction with the rest of your equipment.
Most drysuit manufacturers supply wet-style hoods with their suits. This avoids any problem with reversed-ear, a painful yet avoidable condition, during ascent. Most divers opt for wet gloves too, although there are a couple of makes of dry glove available.