CHAPTER 6 Operational Planning
Change A 6-17
operations using MK 16 UBA, MK 25 UBA, Viper VSW UBA, SCUBA, and
surface supplied UBA in water temperatures up to 99°F. Diving in water tempera-
tures above 99°F should not be attempted without first contacting NAVSEA 00C.
Operational Guidelines and Safety Precautions. These guidelines are based on
data collected from heat acclimated divers dressed in UDT swim trunks and t-
shirts who were well rested, calorically replete, well hydrated, and had no imme-
diate heat exposure prior to starting exercise. Exercise rate for the divers
replicated a moderate swimming effort. Conditions that contribute to thermal
loading such as heavy work rates, significant pre/post dive activities, and various
diver dress (dive skins/wetsuits/dry suits) can reduce exposure limits appreciably.
Define guidelines for exposure limits based on diver dress are currently being
developed by NEDU. Until further guidance is provided regarding the measurable
effects of these factors, the limits provided shall serve as maximum levels of
The following precautions apply to all warm water diving operations above 88°F:
Weight losses up to 15 lbs (or 6-8% of body weight) due to fluid loss may
occur and mental and physical performance can be affected. Divers should
hydrate fully (approximately 500 ml or 17 oz) two hours before diving. Fluid
loading in excess of the recommended 500 ml may cause life-threatening pul-
monary edema and should not be attempted.
Hydrating with water or a glucose/electrolyte beverage should occur as soon
as possible after diving. Approximately 500 ml should be replaced for each
hour of diving.
Exposure limits represent maximum cumulative exposure over a 12 hour
period. Divers should be hydrated and calorically replete to baseline weight,
rested, and kept in a cool environment for at least 12 hours before a repeat
exposure to warm water is deemed safe.
This guidance does not change NAVSEA-approved canister duration
limits for the MK 16, MK 25, and Viper VSW UBAs. Maximum warm water
dive time exposure limits for these UBAs shall always be the lesser of
the approved UBA canister duration limits or diver physiological
The following guidance is broken down into specific UBAs:
MK 25 UBA A diver working at a moderate rate, swimming at 0.8 kts or less
88°-94°F - limited to canister/O2 bottle duration
94°-97°F - limited to three hours based on physiological limits.
97°-99°F - limited to one hour based on physiological limits.