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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.
Contents
- Usage
- Designed to be worn all the time
- Only worn in emergency vessel abandonment
- Construction
- Open neck vs closed neck sealing
- Safety features
- Inflatable survival suits
- Immersion suit maintenance
- References
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 boilersuit.
The ancestor of these suits was already invented in 1872 by Clark S Merriman to rescue steamship passengers. It was made from rubber sheeting and became famous by the swim records of Paul Boyton. It was essentially a pair of rubber pants and shirt cinched tight at the waist with a steel band and strap. Within the suit were five air pockets the wearer could inflate by mouth through hoses. Similar to modern-day drysuits, the suit also kept its wearer dry. This essentially allowed him to float on his back, using a double-sided paddle to propel himself, feet-forward. Additionally he could attach a small sail to save stamina while slowly drifting to shore (because neither emergency radio transmitters nor rescue helicopters were invented yet).
The first immersion suit to gain USCG approval was invented by Gunnar Guddal. Eventually the suit became accepted as essential safety gear.
Usage
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 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.
Only worn in emergency / vessel abandonment
The first survival suits in Europe were invented by Daniel Rigolet, captain of a French oil tanker. Others had experimented on similar suits abroad.
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 liferaft when the sailor reaches the surface.
Construction
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.
Safety features
Survival suits can also be equipped with extra safety options such as:
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.
Immersion suit maintenance
Each immersion suit needs to be regularly checked and maintained properly in order to be ready for use all the time. The maintenance of the immersion suits kept on board of the vessels must be done according to the rules of the International Maritime Organization (IMO). There are two Guidelines issued by IMO - MSC/Circ.1047 and MSC/Circ.1114 in relation to immersion suits’ maintenance.
The first one gives instruction for monthly inspection and maintenance which must be done by the ship’s crew. The second one is concerning pressure testing which can be done only with special equipment. Usually it is done ashore by specialized companies but can be done also onboard of the vessels if practical. It must be performed every three years for immersion suits less than 12 years old and every second year on older ones. The years are counted from the suit’s date of manufacture.