Drysuits
Drysuits, as the name suggests, are designed to keep you dry! Unlike wetsuits and semi-drysuits, which allow in a layer of water, which your body then warms up, as insulation, a drysuit uses neck and cuff seals, and built-in boots, to trap a layer of air between the suit and the diver’s body.
Depending on the type of material used to make the drysuit, and how cold the water they are diving in is, the diver can then use layers of warm dry clothes to insulate themselves from the outside water.
Drysuits come in two types of material – neoprene and membrane. Neoprene drysuits come in ‘normal’ and then compressed or crushed variants. Normal neoprene drysuits use the thickness of the suit material to insulate the body and are generally used with a thin underlayer.
Compressed or crushed neoprene drysuits can vary from 2mm-5mm thick and, as the name suggests, they are made from ‘normal’ neoprene which is then compressed or crushed to make it far thinner. The benefits are two-fold – they are easier to move about in, and there is virtually no compression at depth – but they do tend to be quite expensive, heavy and can take ages to dry.
Membrane drysuits are thinner than neoprene suits and have no inherent buoyancy, so an undersuit is required for insulation. They are typically made out of a thin skin of nylon-butyl-trilaminate, or rubber, hence why they are also sometimes called ‘trilaminate drysuits’ instead of membrane.
By the very nature of the material they are made of, membrane suits generally fit looser, to allow full movement. Being lightweight, they are ideal for travelling with, and they dry quickly. There are two types of material used for the neck and cuff seals – neoprene and latex.
Neoprene tends to be more comfortable and warmer, but it can be harder to take on and off; latex is easy to put on and take off, but it doesn’t have any thermal properties. Both kinds of seals can be fitted to both kinds of drysuit.
Obviously, a drysuit that allows air to be added as you dive forms another buoyancy chamber, which then needs venting as you ascend. To this end, drysuits have inflators attached on the chest that allow the diver to inject air as their depth increases.
To allow this air to escape on ascent, drysuits either have a one-way valve on the left cuff or an auto-dump on the left shoulder. A cuff dump requires the diver to raise their arm, thus making it the highest point and allowing air to escape. An auto-dump can be set so that it automatically vents the air as the diver ascends. Again, both kinds of dump can be fitted to all.
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