DICTIONARY OF

Toleration 356 Topgallant Mast
Toleration. Amount of inaccuracy that can be accepted in any item that is made to specified
dimensions.
Tom, Tomm. To shore up. 2. A shore, or support.
Tomahawk. Small pole axe used for fire-fighting, and other purposes.
Tom Bowling. The ideal seaman. Immortalised in Dibden's song, and in Smollett's
'Roderick Random'.
Tom Cox's Traverse. Work done by a man who bustles about doing nothing. Usually
amplified by adding 'pinning twice round the scuttle butt and once round the longboat'.
Tompion. Plug put in muzzle of gun to keep bore clean and watertight.
Tongue. Upper main piece of a built mast. 2. Rope spliced into upper part of a standing
backstay. 3. Clapper of a bell.
Tonnage. Expression of a ship measurement that is not necessarily based on weight. In some
cases it is derived from cubic capacity - this usage being ascribed to the number of 'tuns' that
would stow in the space. The principal ship tonnages are Gross, Net, Displacement,
Deadweight, and Under Deck tonnages.
Tonnage Deck. That deck that forms the upper boundary of the space measured when
assessing tonnage. In vessels having less than three complete decks it is the upper deck. In
all other cases it is the second deck from below.
Tonne. Metric unit of weight. Equals 0.9842 avoirdupois ton and 1000 kilo.
Tons Burden. Carrying capacity of a vessel expressed in tons. In Section 3 of Merchant
Shipping Act it means 'net registered tonnage'.
Tons per Inch. Number of tons required to increase a vessel's draught by one inch at a given
draught.
Top. Platform at head of lower mast. Rests on trestle trees and thwartship bearers. Gives a
good spread to upper rigging. 2. Division of the watch in Royal Navy.
Top Block. Iron-bound block, connected to eyebolt under lower cap, to take the top rope
when sending topmast up or down.
Top Brim. Top rim.
Top Button. Truck at a mast head.
Top Chains. Preventers, in sailing warships, that took weight of the lower yard if slings
were shot away.
Top End. Rectangular block at lower end of piston of a marine reciprocating engine. Upper
end of connecting rod is hinged into it.
Topgallant Bulwarks. 'Quarter boards.'
Topgallant Forecastle. Short deck right forward, and raised above the upper deck, to carry
machinery for working cable.
Topgallant Mast. Mast above topmast. When royal yards are crossed the mast is longer: the
upper part being the royal mast, the lower part being the topgallant mast.