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An immersion suit, or survival suit (or more specifically an immersion survival suit), is a special type of waterproof dry suit that protects the wearer from hypothermia from immersion in cold water, after abandoning a sinking or capsized vessel, especially in the open ocean. They usually have built-on feet (boots), and a hood, and either built-on gloves or watertight wrist seals.
The first record of a survival suit was in 1930 when a New York firm American Life Suit Corporation offered merchant and fishing firms what it called a safety suit for crews of ocean vessels. The suit came packed in a small box and was put on like a pair of coveralls. [1]
These suits are in two types:
This type is chosen to fit each wearer. They are often worn by deep-sea fishermen who work in cold-water fishing grounds.
Some of these garments overlap into scubadiver-type drysuits. Others may have many of the features of a survival suit.
Since humans are warm blooded and sweat to cool themselves, suits that are worn all the time usually have some method for sweat to evaporate and the wearer to remain dry while working.
Unlike work suits, "quick don" survival suits are not normally worn, but are stowed in an accessible location onboard the craft. The operator may be required to have one survival suit of the appropriate size onboard for each crew member, and other passengers. If a survival suit is not accessible both from a crew member's work station and berth, then two accessible suits must be provided.
This type of survival suit's flotation and thermal protection is usually better than an immersion protection work suit, and typically extends a person's survival by several hours while waiting for rescue.
An adult survival suit is often a large bulky one-size-fits-all design meant to fit a wide range of sizes. It typically has large oversize booties and gloves built into the suit, which let the user quickly don it on while fully clothed, and without having to remove shoes. It typically has a waterproof zipper up the front, and a face flap to seal water out around the neck and protect the wearer from ocean spray. Because of the oversized booties and large mittens, quick don survival suits are often known as "Gumby suits," after the 1960s-era children's toy.
The integral gloves may be a thin waterproof non-insulated type to give the user greater dexterity during donning and evacuation, with a second insulating outer glove tethered to the sleeves to be worn while immersed.
A ship's captain (or master) may be required to hold drills periodically to ensure that everyone can get to the survival suit storage quickly, and don the suit in the allotted amount of time. In the event of an emergency, it should be possible to put on a survival suit and abandon ship in about one minute.
The Submarine Escape Immersion Equipment is a type of survival suit that can be used by sailors when escaping from a sunken submarine. The suit is donned before escaping from the submarine and then inflated to act as a life raft when the sailor reaches the surface.
Survival suits are normally made out of red or bright fluorescent orange or yellow fire-retardant neoprene, for high visibility on the open sea. The Neoprene material used is a synthetic rubber closed-cell foam, containing a multitude of tiny air bubbles making the suit sufficiently buoyant to also be a personal flotation device.
The seams of the neoprene suit are sewn and taped to seal out the cold ocean water, and the suit also has strips of SOLAS specified retroreflective tape on the arms, legs, and head to permit the wearer to be located at night from a rescue aircraft or ship.
The method of water sealing around the face can affect wearer comfort. Low-cost quick-donning suits typically have an open neck from chest to chin, closed by a waterproof zipper. However the zipper is stiff and tightly compresses around the face resulting in an uncomfortable fit intended for short-duration use until the wearer can be rescued. The suit material is typically very rigid and the wearer is unable to look to the sides easily.
Suits intended for long-term worksuit use, or donned by rescue personnel, typically have a form-fitting neck-encircling seal, with a hood that conforms to the shape of the chin. This design is both more comfortable and allows the wearer to easily turn their head and look up or down. The suit material is designed to be either loose or elastic enough to allow the wearer to pull the top of the suit up over their head and then down around their neck.
Survival suits can also be equipped with extra safety options such as:
The inflatable survival suit is a special type of survival suit, recently developed, which is similar in construction to an inflatable boat, but shaped to wrap around the arms and legs of the wearer. This type of suit is much more compact than a neoprene survival suit, and very easy to put on when deflated since it is just welded from plastic sheeting to form an air bladder.
Once the inflatable survival suit has been put on and zipped shut, the wearer activates firing handles on compressed carbon dioxide cartridges, which punctures the cartridges and rapidly inflates the suit. This results in a highly buoyant, rigid shape that also offers very high thermal retention properties.
However, like an inflatable boat, the inflatable survival suit loses all protection properties if it is punctured and the gas leaks out. For this reason, the suit may consist of two or more bladders, so that if one fails, a backup air bladder is available.
