For those of us who dive regularly in temperate waters, the use of a drysuit is born out of necessity rather than choice. Without that warm and dry insulating layer around us, we’d soon fall victim to the hypothermic effect of the liquid environment that so quickly conducts heat into the waters surrounding us. Drysuits come in many different styles and shapes and are manufactured in a variety of materials. Body shape, the individual diver’s tolerance to temperature extremes and the type of diving undertaken are all factors which must be considered when choosing a suit. A correctly fitting drysuit should give many years of service and, as possibly the single largest investment in equipment a diver will make, it’s important to make the right decision...
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A drysuit is a big investment, and it’s essential you get the right one for you and the diving you do. Don’t be left high and dry – here’s DIVE’s guide to choosing a suit. By Neil Hope
Drysuits are designed to do what they say – to keep you dry. They must also be comfortable in and out of the water and, when combined with a suitable thermal undergarment, warm.
The two main types of suit are those commonly referred to as either neoprene or membrane. Neoprene is a flexible, synthetic rubber containing minute bubbles of nitrogen. This offers good insulating properties through a wide range of temperatures, but with depth and increased pressure these bubbles compress, meaning a 6mm layer of neoprene at the surface offers far less thermal protection at a depth of 30 metres than it does at the surface.
To offset this compression, the majority of neoprene drysuits are now produced as either compressed or crushed versions to reduce the bubble factor. The former are generally considered as offering superior warmth and longevity, although due to higher manufacturing costs this may often be at a premium.
Membrane or trilaminate suits can be made from a variety of different materials, but commonly feature a sandwiched layer of thin and waterproof neoprene or butyl between their inner and outer surfaces. Lightweight and quick to dry, although more bulky, membrane suits in themselves do not offer such good heat-retaining properties as neoprene. However, in conjunction with a suitable undersuit they are equally adept at keeping the diver warm, while also proving easier to put on in normal circumstances.
Always try on a drysuit wearing the undersuit you’ll be diving in. A suit that feels just fine in a T-shirt and shorts may well prove a little more problematic when matched with thicker thermal protection underneath it. Too big a fit and the excess air contained within may require substantially more weight than normally required, while too small a suit will result in compromised movement.
To ensure you have both a full range of movement and the all-important ability to reach your essential equipment, such as tank valves, there are a few exercises you can do which will help you to eliminate an ill-fitting choice relatively easily.
- Raise each arm individually and reach back as if attempting to access your cylinder valve and then repeat with both arms – if you’re unable to complete this manoeuvre, the suit is too small.
- With feet planted flat on the ground, lower yourself to a squat and assume the ‘Cossack’ position – movement should be easy and unrestricted.
- Kneel down with the other leg trailing behind then change over – again, there should be no tightness or restricted movement.
- Finally, stand up straight and push both legs out sideways as if attempting to do the splits – if the suit is undersize the crotch will be too low and will prevent the manoeuvre.
Don’t be afraid to experiment with any combination of the exercises.
Although most drysuits follow the same general layout, it’s good practice to wear your preferred choice of BCD to ensure there are no possible conflicts with straps, webbing etc.
Correctly fitting and functioning cuff and neck seals are of obvious importance. If they aren’t watertight, that slight trickle of water down the back of the neck can easily become a precursor to a cold, uncomfortable and prematurely ending dive.
Neck and cuff seals are available in a choice of either smooth neoprene or flexible latex rubber and should be well fitting without cutting off essential circulation – especially around the neck.
Of the two, latex offers the more effective seal but does have a shorter lifespan and is more prone to accidental damage. Many suits feature a combination of a latex seal with a neoprene collar for added warmth and protection.
Neoprene does have a tendency to allow the occasional dribble of water to seep inside the suit during extreme reaching and stretching movements, therefore neck seals are inverted on themselves to keep the air in and water out. Although some small water ingress is almost inevitable at some stage, due to the nature of the thicker and stiffer material, the twin benefits of hardiness and longevity are a legitimate consideration.
The most common position for pockets are for them to be either front- or side-mounted on the thigh. Pockets can prove a useful aid for the purpose of stowing slates, reels and even compact cameras.
However, if over large, they can also cause excessive drag during swimming. It’s worth giving careful consideration to the pros and cons of large or small pockets and which would be most advantageous to your personal style of diving and how you configure your kit when selecting your suit. A good time to question just how much you lug around.
There are various ways of bonding the sections of material that make up a drysuit. These include stitching, taping, gluing and welding or any combination of these methods. Regardless of the particular process involved, the successful operation of any drysuit relies directly on the integrity of its seams and close attention should be paid to these areas both inside and out.
On descent, air within the drysuit compresses and needs additional gas to stay at a constant volume. A chest-mounted direct feed valve is the solution and also doubles as a form of buoyancy control. Preferably rotating, the valve can then be accessed from either side to allow hose routing as required.The air must also be allowed to escape during ascent, and the simplest solution is via a cuff-mounted dump, which works by extending the arm to vent through a one-way valve. Not ideal for underwater photographers for obvious reasons, an automatic shoulder version allows user- adjustment by way of a spring-operatedvalve to keep the constant volume of gas inside the suit as required.
Made from hardwearing moulded rubber, boots are normally attached directly to the suit and often lined for warmth. Size is dependent on the preferred thermal protection – wearing Thinsulate-type socks, for instance, would require at least a size above the norm. They should also be a close fit to avoid migration of air to the feet and avoid an unwanted inverted ascent.
Some drysuits have dispensed with fitted boots, instead ending the suit with a closed sock arrangement at the feet and employing separate, hard-soled lightweight hiking-boot-style footwear.
As the main entry to any drysuit, the zip must be capable of sustained and heavy use. Traditional drysuits feature a rear waterproof shoulder-to-shoulder zip that may feature an outer flap as protection.
Self-donning drysuits can offer either a front-mounted diagonal shoulder to hip version or a ‘u’-shaped chest entry as an alternative. Regular maintenance and lubrication are essential to keep the zip in working order.
As with any garment, diving or otherwise, certain areas will always see more wear than others, and extra reinforcement in these high-use regions is essential. Whether kitting up, kneeling on a rocky shore or exploring a wreck, it’s often the knee area that suffers most, and a double-thickness of material or bonded knee-pads guard against premature wear or possible damage.
Alternatively, divers can purchase adjustable slip-on knee pads offered by some dive gear manufacturers. Materials used are double-layered neoprene or Kevlar, a synthetic fibre which, under water, is 20 times stronger than steel. They guarantee extra protection and better grip and are particularly useful for underwater photographers and wreck divers.
A neoprene drysuit’s heat-retaining qualities offer considerably more protection than that of the membrane design, but even the best-fitting suit needs an effective method of thermal insulation to prevent heat loss. Undersuits can be divided roughly into the two main types of fleece-style or Thinsulate.
A blend of synthetic fibres, Thinsulate offers improved insulation over other materials such as polyester. It allows excellent heat retention but also the ability for moisture to pass though to its surface away from the skin. This type of undersuit is typically one-piece and best suited to use in tandem with a membrane drysuit.
Fleece undersuits are manufactured using fast-wicking, high-insulation fabrics. By selecting different layers according to the prevailing conditions they prove a very effective solution for closer fitting neoprene drysuits.
Drysuit care & maintenance
With a little care and attention there’s every reason to expect a drysuit to give many years of sterling service, and following a regular, simple maintenance regime after diving will make all the difference
• Post-dive, thoroughly rinse your drysuit both inside and out, paying particular attention to the valves and zip ensuring they are free from dirt, sand and grit.
• Latex seals are particularly susceptible to damage caused by contact with oil, petrol or similar contaminants – any chemical solvents should be cleaned off immediately with soapy water then rinsed in clean fresh water.
• Suspend the suit upside down in a well-ventilated area, away from direct heat or sunlight and when fully dry, lightly brush with talc or French chalk to prevent latex seals perishing. Avoid scented talcum powder as it can often contain harmful petroleum.
• The zip should be checked for integrity and movement to avoid any snagging that may cause damage to the teeth. Finally it should be lubricated with a beeswax stick or a similar specifically designed product.
• Store your drysuit hanging up to avoid creasing of the material and any strain on the zipper. If you’re unable to store it hanging up make sure that you pack it carefully and the zip is flat, not folded or kinked.