46 CFR 160.171-11: Immersion suit performance requirements
Last reviewed: October 14, 2026
This section sets the performance requirements each immersion suit must meet. It covers buoyancy, righting, thermal protection, donning time, vision, water penetration, splash protection, storage temperature, flame exposure and oil resistance.
Applies toImmersion suits, including adult, oversize adult and child size suits.
What it says
The adjusted buoyancy of each adult and each oversize adult size suit must be at least 100 N (22 lb.).
46 CFR 160.171-11(a)(1)“The adjusted buoyancy of each adult and each oversize adult size suit must be at least 100 N (22 lb.).”
The adjusted buoyancy of each child size suit must be at least 50 N (11 lb.).
46 CFR 160.171-11(a)(1)“The adjusted buoyancy of each child size suit must be at least 50 N (11 lb.)”
Each suit must have a stable floating position in which the wearer's head is tilted to a position between 30° and 80° above the horizontal.
46 CFR 160.171-11(a)(2)“Each suit must have a stable floating position in which the wearer's head must be tilted to a position between 30° and 80° above the horizontal”
The buoyancy of any auxiliary means of buoyancy must not be counted when determining the buoyancy of the suit.
46 CFR 160.171-11(a)(4)“The buoyancy of any auxiliary means of buoyancy must not be counted when determining the buoyancy of the suit.”
The suit must give the wearer enough thermal insulation, after one jump into the water from a height of 4.5 m, that the wearer's body core temperature does not fall more than 2 °C (3.6 °F) after 6 hours of immersion in calm circulating water.
46 CFR 160.171-11(c)(2)“to ensure that the wearer's body core temperature does not fall more than 2 °C (3.6 °F) after a period of 6 hours immersion”
Each suit must be designed so that a person can don it correctly within two minutes after reading the donning and use instructions described in § 160.171-15(a).
46 CFR 160.171-11(d)“Each suit must be designed so that a person can don the suit correctly within two minutes after reading the donning and use instructions described in § 160.171-15(a).”
Each suit must have a means to prevent water spray from directly entering the wearer's mouth.
46 CFR 160.171-11(g)“Each suit must have a means to prevent water spray from directly entering the wearer's mouth.”
Each suit must be designed to prevent sustained burning or continued melting after it is totally enveloped in a fire for a period of 2 seconds.
46 CFR 160.171-11(i)“Each suit must be designed to prevent sustained burning or continued melting after it is totally enveloped in a fire for a period of 2 seconds.”
Common questions
How much buoyancy must an adult immersion suit have?
The adjusted buoyancy of each adult and each oversize adult size suit must be at least 100 N (22 lb.). The measured buoyancy must not be reduced by more than 5% after 24 hours submersion in fresh water.
“The measured buoyancy must not be reduced by more than 5% after 24 hours submersion in fresh water.”
How fast must a person be able to put on an immersion suit?
Each suit must be designed so that a person can don it correctly within two minutes after reading the donning and use instructions described in § 160.171-15(a).
“Each suit must be designed so that a person can don the suit correctly within two minutes after reading the donning and use instructions described in § 160.171-15(a).”
What storage temperatures must an immersion suit withstand?
Each suit must be designed so that it will not be damaged by storage in its storage case at any temperature between −30 °C (−22 °F) and + 65 °C (149 °F).
“Each suit must be designed so that it will not be damaged by storage in its storage case at any temperature between −30 °C (−22 °F) and + 65 °C (149 °F).”
Can auxiliary buoyancy interfere with righting an immersion suit wearer?
No. Auxiliary buoyancy, if fitted or inflated, must not interfere with righting.
“Auxiliary buoyancy, if fitted and/or inflated, must not interfere with righting.”
The text of 46 CFR 160.171-11
Electronic Code of Federal Regulations (eCFR), current as of March 31, 2026 · Read it on eCFR
Performance
(a) Buoyancy. Each suit must meet the following buoyancy requirements as measured in the test conducted under § 160.171-17(h):
(1) The adjusted buoyancy of each adult and each oversize adult size suit must be at least 100 N (22 lb.). The adjusted buoyancy of each child size suit must be at least 50 N (11 lb.) The measured buoyancy must not be reduced by more than 5% after 24 hours submersion in fresh water.
(2) Each suit must have a stable floating position in which the wearer's head must be tilted to a position between 30° and 80° above the horizontal, with the mouth and nose at least 120 mm (4 3/4 in.) above the surface of the water. If necessary, this position may be obtained through the use of an auxiliary means of buoyancy such as an inflatable bladder behind the wearer's head.
(3) If an auxiliary means of buoyancy is necessary to meet paragraph (a)(2) of this section, the suit must have a stable floating position without the auxiliary means of buoyancy in which the mouth and nose of the wearer are at least 50 mm (2 in.) above the surface of the water.
(4) The buoyancy of any auxiliary means of buoyancy must not be counted when determining the buoyancy of the suit.
(b) Righting. The suit must be designed to turn the body of an unconscious person in the water from any position to one where the mouth is clear of the water in not more than five seconds, without assistance or the use of any means of auxiliary buoyancy which must be inflated by the wearer; or to allow the wearer to turn from a face down to a face up position in not more than 5 seconds, without assistance or the use of any means of auxiliary buoyancy. If an automatically inflated means of auxiliary buoyancy is used to meet this paragraph, the inflation mechanism must meet the requirements for commercial hybrid PFDs in § 160.077-15(c) of this chapter, and the tests required under § 160.077-21(c)(3) of this chapter. Auxiliary buoyancy, if fitted and/or inflated, must not interfere with righting.
(c) Thermal protection. The suit must be designed to protect against loss of body heat as follows:
(1) The thermal conductivity of the suit material when submerged 1 m (39 in.) in water must be less than or equal to that of a control sample of 4.75 mm ( 3/16 in.) thick, closed-cell neoprene foam. The control sample of foam must have a thermal conductivity of not more than 0.055 watt/meter−° K (0.38 Btu−in./hr.−sq.ft.− °F).
(2) The suit must provide the wearer with sufficient thermal insulation, following one jump into the water from a height of 4.5 m, to ensure that the wearer's body core temperature does not fall more than 2 °C (3.6 °F) after a period of 6 hours immersion in calm circulating water at a temperature of between 0 °C (32 °F) and 2 °C (35.6 °F).
(d) Donning time. Each suit must be designed so that a person can don the suit correctly within two minutes after reading the donning and use instructions described in § 160.171-15(a).
(e) Vision. Each suit must be designed to allow unrestricted vision throughout an arc of 60° to either side of the wearer's straight-ahead line of sight when the wearer's head is turned to any angle between 30° to the right and 30° to the left. Each suit must be designed to allow a standing wearer to move head and eyes up and down far enough to see both feet and a spot directly overhead.
(f) Water penetration. An immersion suit must be designed to prevent undue ingress of water into the suit following a period of flotation in calm water of one hour.
(g) Splash protection. Each suit must have a means to prevent water spray from directly entering the wearer's mouth.
(h) Storage temperature. Each suit must be designed so that it will not be damaged by storage in its storage case at any temperature between −30 °C (−22 °F) and + 65 °C (149 °F).
(i) Flame exposure. Each suit must be designed to prevent sustained burning or continued melting after it is totally enveloped in a fire for a period of 2 seconds.
(j) Oil resistance. Each immersion suit must be designed to be useable after a 24 hour exposure to diesel oil.
Sections it refers to
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of March 31, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.