Glossary of SCUBA Diving - T

T

taravana

A form of decompression sickness found among Polynesian island natives who habitually do multiple repetitive deep breath-hold dives.

task loading

A multiplicity of responsibilities leading to an increased risk of failure on the part of the diver to undertake some key basic function which would normally be routine for safety

taut wire system

A constant tension wire from a vessel to a weight on the seabed used as a reference to detect movement of a dynamically positioned vessel from the reference point.

technical diving

An extension of the scope of recreational scuba diving to applications with greater technical complexity and higher inherent risk. Definitions vary, but diving with multiple breathing gases, helium based gases, closed circuit rebreathers, or under extensive overheads are generally considered as technical diving. There is no sharp distinction from other forms of recreational diving.

tension leg rig

A vertically moored floating structure normally used for the offshore production of oil or gas, particularly suited for water depths between 300 and 1500 meters. The platform is permanently moored by means of tethers at each of the structure's corners and virtually all vertical motion of the platform is eliminated.

test pressure

Pressure at which the cylinder will be hydrostatically tested for revalidation. Usually 1.5 or 1.67 x working pressure.

therapeutic recompression

Further information: Hyperbaric medicine, Decompression (diving)#Therapeutic decompression, and Decompression sickness#Treatment

A procedure for treating decompression sickness by recompressing the diver, thus reducing bubble size, and allowing the gas bubbles to re-dissolve, then decompressing slowly enough to avoid further formation or growth of bubbles, or eliminating the inert gases by breathing oxygen under pressure

thermocline

A thin but distinct layer in a large body of fluid, in which temperature changes more rapidly with depth than it does in the layers above or below

thermodynamic decompression model

Further information: Decompression (diving)#The no-supersaturation approach

Hypothesis that bubble formation during decompression will not occur provided absolute ambient pressure exceeds the total of the partial gas tensions in the tissue for each gas.

through-water communications

Wireless voice communications transmitted through the water

time to fly

The surface interval necessary after diving to reduce tissue gas concentrations to a level where the risk of decompression sickness due to the pressure reduction experienced in normal commercial airliners is acceptable.

tinnitus

The perception of sound within the human ear in the absence of corresponding external sound

tissue compartments

Further information: Decompression (diving)#Tissue compartments

Imaginary tissues which are designated as fast and slow to describe the rate of saturation.

tissue half times

Further information: Decompression (diving)#Tissue half times

The time it takes for the tissue to take up or release 50% of the difference in dissolved gas capacity at a changed partial pressure.

TNT

1. Total Nitrogen Time: Equivalent time of hyperbaric exposure for a repetitive dive used with some decompression tables.

2. Trinitrotoluene, a high explosive

top up

To reconnect a partially filled cylinder and add gas until the pressure is within tolerance of the required charging pressure when corrected for temperature.

Toynbee manouevre

Method of equalising the middle ears by pinching the nose and swallowing.

trait anxiety

Further information: Anxiety#Trait anxiety

A tendency to respond with anxiety in the anticipation of threatening situations.

trauma shears

also bandage scissors or paramedic shears

Blunt tipped slightly serrated shears with angled blades sometimes used by divers as a safety cutting implement in place of a knife or line cutter.

tremie

A pipe, through which concrete is placed below water level. The top of the tremie is above water and open, and the bottom end is kept below the surface of the poured concrete.

trimix

Mixture of three gases for breathing. Oxygen, nitrogen and helium are the gases used. The gas fractions will usually be specified.

tube

A seamless transportable compressed gas container, with a water capacity exceeding 150 litres (5.3 cu ft) but not more than 3,000 litres (110 cu ft); Often mounted horizontally in manifolded groups on a trailer or intermodal container frame.

TUP

Transfer Under Pressure: Transfer of personnel between hyperbaric environments, usually between a closed bell and a saturation system, or between a portable recompression chamber and a multi-occupant chamber

turbidity

The cloudiness or haziness of a fluid caused by individual particles (suspended solids) that may be invisible to the naked eye, similar to smoke in air