DICTIONARY OF

Tsunami 366 Turbulence
Tsunami. Wave generated by an under-water upheaval of the earth's crust. Can travel great
distances and cause destruction on arrival at a coast. Improperly called a tidal wave.
Tube Plates. Perforated plates in combustion chamber and front end of marine boiler. They
take front ends of smoke return tubes, which are fitted between them.
Tubinares. Means Tubular nostrils.' Applied to petrels, in which this characteristic is
pronounced.
Tuck. After part of vessel, where bottom planking comes to the counter.
Tuck a Strand. To pass end of one strand under an unlaid strand when splicing.
Colloquially: to gain an advantage, or favourable notice.
Tuck Rail. Lower strake of horizontal timber in counter of a wooden vessel.
Tufa. Light porous stone, rather like sandstone, that sometimes contains vegetable matter.
Tug. Strongly-built and fully-engined vessel especially designed for towing.
Tugboat. A small tug.
Tumble Home. The inward inclination of a vessel's sides due to her breadth at upper deck
being less than her maximum breadth.
Tumbler. Hinged pin on which end link of chain holding an anchor is placed. When shafton
which pin is fixed-rotates, the link I falls off and anchor is released.
Tumbler Bolt. Device used for making good a missing rivet, and other purposes, when
outside of plating is inaccessible. Works on the principle of a toggle. Consists of a circular
rod having a slot in which a piece of steel, of same size as slot, is pivoted off centre. Inboard
end of rod is threaded. When passed through hole the hinged part falls at right angles to bolt;
nut on inboard end is screwed up to clamp leak-stopping unit in place.
Tun. Large cask holding 252 gallons (four hogsheads) of wine. 2. Wine measure of same
quantity.
Tunnage. Duties levied on every tun of wine, and pound of goods, shipped from or to
England. Introduced about 1348. Was the beginning of the present Customs duties.
Tunnel. Arched casing around propeller shafting. Extends upwards in after holds of cargo
vessels with engines amidships. Goes to stern gland and allows access to propeller shaft
bearings.
Turbine. Machine in which rotary motion is produced by high velocity of a fluid acting on
blades appropriately mounted in its path. Can be divided into two types, 'impulse' and
'reaction'. Broadly stated, an impulse turbine is turned in same manner as an undershot water
mill; reaction turbine being turned on same principle as a windmill. Marine turbines are
steam or (petroleum) gas-driven. The latter needing no boilers.
Turbulence. Disturbed, or eddying, movement of any fluid when passing over any
obstruction-solid, liquid, or gaseous-in its path. Is of importance in meteorology.