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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.
These suits are in two types:
Designed to be worn all the time
This type is chosen to fit each wearer. They are often worn by deep-sea fishermen who work in cold-water fishing grounds.
- Some aircraft pilot survival suits are constructed of a breathable material that allows water vapor to escape but prevents liquid from entering. Some examples include Gore-Tex as well as a special cotton material containing very long fibers, which swell up when wet and close air pores in the suit.
- Some aircraft pilot survival suits use a solid impregnable material such as rubber-backed cotton, which is connected to a forced-air cooling system. Ventilation air is supplied via air hoses inside the vehicle cabin. In an emergency the hoses can be rapidly disconnected and the ventilation access ports close on the suit.
Only worn in emergency / Ship or Vessel Abandonment (Evacuation)
Unlike work suits, "quick don" survival suits are not normally worn, but are stowed in an accessible location on board the craft. The operator may be required to have one survival suit of the appropriate size on board 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.
Open neck vs closed neck sealing
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:
- A whistle on a lanyard to permit the wearer to signal for help
- An emergency strobe light beacon with a water-activated battery
- An inflatable air bladder to lift the wearer's head up out of the water
- Tethered mittens to better insulate the hands
- An emergency radio locator beacon
- A "Buddy line" to attach to others' suits to keep the group together for rescue
- Sea dye markers to increase visibility in water
Inflatable survival suits
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.
Naval air pilot's immersion suit, with NBC mask with full rubber hood so it can be used as a hazmat suit
- Image of an immersion suit with accessories labeled
- https://www.machovec.com/ice_rescue/images/Survival%20-%20Front.JPG (big image, 1682 x 2190 pixels)