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TONNAGE

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Originally appearing in Volume V27, Page 11 of the 1911 Encyclopedia Britannica.

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TONNAGE . The mode of ascertaining the tonnage of See also:

MERCHANT (O. Fr. marcheant, modern marchand; from Lat. mercari, to trade, merx, goods, merchandise)

merchant See also:

SHIPS

ships is settled by the Merchant See also:

SHIPPING

Shipping Acts. But before explaining the method by which this is computed, it is well to remark that there are several tonnages employed in different connexions. Displacement tonnage is that which is invariably used in respect of warships, and is the actual See also:

WEIGHT

weight of See also:

WATER

water displaced by the See also:

VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel whose tonnage is being dealt 1 See also:

JOWETT, BENJAMIN (1817-1893)

Jowett's See also:

TRANSLATION

translation.with. Men-of-See also:

War are designed to carry all their weights, including See also:

COAL

coal, guns, See also:

AMMUNITION

ammunition, stores and water in tanks and in boilers, at a certain See also:

DRAUGHT (from the common Teutonic word " to draw "; cf. Ger. 7'racht, load; the pronunciation led to the variant form " draft," now confined to certain specific meanings)

draught, and the tonnage attributed to them is the weight of water which at that designed draught they actually displace. This displacement tonnage is therefore a See also:

TOTAL

total made up of the actual weight of the See also:

SHIP

ship's fabric and that of everything that is on See also:

BOARD (O. Eng. bord)

board of her. It can be found by ascertaining the exact cubic space occupied by the See also:

PART

part of her See also:

BODY

body which is immersed (including her See also:

RUDDER (O.E. Rather, i.e. rower)

rudder, propellers and See also:

EXTERNAL

external shafting) at the draught under See also:

CONSIDERATION (from Lat. considerare, to look at closely, examine, generally taken to be from con-, and the base seen in sidus, sideris, a star, the word being supposed to be originally an astrological or astronomical term)

consideration in cubic feet, and dividing this by 35, since 35 cubic feet of See also:

sea-water weigh one ton. Of course there is nothing to prevent displacement tonnage from being used in describing the See also:

SIZE

size of merchant ships, and indeed in regard to the performances of fast See also:

steam-ships on trial it is usual to give their draught on the occasion when they are tested, and to See also:

state what was their actual displacement under these trial conditions. But it is obvious, from what has been said as to the components which go to make up the displacement at load draught, that this tonnage must, in respect of any individual ship, be the greatest figure which can be quoted in regard to her size. It is usual for dues to be assessed against merchant vessels in respect of their registered tonnage. This must therefore be fixed by authority, and at See also:

PRESENT

present vessels are measured by the officer of customs according to the rules laid down in the second See also:

SCHEDULE

schedule to the Merchant Shipping See also:

ACT (Lat. actus, actum)

Act 1894. As will be seen from the explanation of the method adopted, this is a somewhat arbitrary See also:

PROCESS

process, and even the See also:

GROSS

gross registered tonnage affords little indication of the actual size of the ship, whilst the under-See also:

DECK

deck and See also:

net tonnages are still less in See also:

ACCORD (from Fr. accorder, to agree)

accord with the extreme dimensions.

As to length for tonnage, the measurements start with the tonnage deck, which in vessels with less than three decks is the upper, and in vessels of three or more decks is the second from below. The length for tonnage is measured in a straight See also:

LINE

line along this deck from the inside of the inner See also:

PLANK

plank at the See also:

BOW (pronounced " bo ")

bow to the inside of the inner plank at the stern, making See also:

ALLOWANCE (from "allow,' derived through 0. Fr. alouer from the two Lat. origins adlaudare, to praise, and allocare, to assign a place; so that the English word combined the general idea of "assigning with approval")

allowance for the See also:

RAKE (O.E. rata, cognate with Du. raak, Ger. Rechen, from a root meaning to scrape together, heap up)

rake, if any, which the midship bow and See also:

STEM (O. Eng. staefn, stemn, cf. Du. stain, Ger. Stamm, &c., probably related to " staff ")

stem timbers may have in the actual deck. When this is measured it is apparent into which of five classes the ship's tonnage-length places her. If she be under 5o ft. in length she falls into the first class, while if she be over 225 ft. in length she falls into the fifth class, the remaining three classes being intermediate to these. Vessels of the first class are measured as in four equal sections, and vessels of the larger class as in twelve equal sections, according to their length. Then at each of the points of See also:

DIVISION (from Lat. dividere, to break up into parts, separate)

division so marked off transverse areas are taken. This is done by measuring the See also:

DEPTH

depth in feet from a point at a distance of one-third of the See also:

ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round of the See also:

beam below the tonnage deck to the upper See also:

side of the See also:

FLOOR (from O. Eng. flor, a word common to many Teutonic languages, cf. Dutch vloer, and Ger. Flur, a field, in the feminine, and a floor, masculine)

floor timbers. Where the vessel has a See also:

CEILING (from a verb " to ceil," i.e. to line or cover; of disputed etymology, but apparently connected with Fr. ciel, Lat. caelum, sky)

ceiling and no water-See also:

BALLAST (O. Swed. barlast, perhaps from bar, bare or mere, and last, load)

ballast tanks at the point of measurement, 21 in. is allowed for ceiling. But where there are such tanks the measurement is taken from the See also:

TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top of the tank and no allowance is made for ceiling, whether there in fact be any or not. If the midship depth so found exceeds 16 ft., each depth is divided into six equal parts, and the See also:

HORIZONTAL

horizontal breadths are measured at each point of division and also at the upper and See also:

LOWER

lower points of the depth, extending each measurement to the See also:

AVERAGE

average thickness of that part of the ceiling which is between the points of measurement. They are then numbered from above, and the second, See also:

FOURTH

fourth and See also:

SIXTH

sixth multiplied by four, whilst the third and fifth are multiplied by two. The products are then added together.

To the sum are added the first and the seventh breadths. This total having been multiplied by one-third the See also:

COMMON

common See also:

INTERVAL

interval between the breadths, the resultant is the transverse See also:

AREA

area. The transverse areas so obtained at each point of the vessel's length are numbered from the bow aft. Omitting the first and last, the second and every even area so obtained are multiplied by four, whilst the third and every See also:

ODD (in middle English odde, from old Norwegian oddi, an angle of a triangle; the old Norwegian oddamann is used of the third man who gives a casting vote in a dispute)

odd area are multiplied by two. These products are added together, as are also those of the first and last areas if they yield anything, and the figure thus reached is multiplied by one-third of the common interval between the areas. This product is reckoned as the cubical capacity of the ship in feet. When divided by See also:

LOO (formerly called " Lanterloo," Fr. lanturlu, the refrain of a popular 17th-century song)

loo the result is the registered under-deck tonnage of the ship—subject to the additions and deductions ordered by the act. Directions of a See also:

KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind similar to those already set out are given whereby the tonnage in the space enclosed between the tonnage and upper decks may be ascertained, and also for the measuring of any break, See also:

POOP (Lat. puppis, stern)

poop or other permanent closed-in space on the upper deck available for stores, and the sum of the capacity of these must be added to the under-deck tonnage to arrive at the gross registered tonnage. But an See also:

EXPRESS (through the French from the past participle of the Lat. exprimere, to press out, by transference used of representing objects in painting or sculpture, or of thoughts, &c. in words)

express proviso is enacted that no addition shall be made in respect of any See also:

BUILDING

building erected for the shelter of deck passengers and approved by the board of See also:

trade. In the process of arriving at the net tonnage the See also:

main See also:

DEDUCTION (from Lat. deducere, to take or lead from or out of, derive)

deduction allowed from the gross tonnage is that of machinery space in steamships. The method of measurement here is similar to that by which the under-deck tonnage is reached. Where the engines and boilers are fitted in See also:

SEPARATE

separate compartments, each compartment is measured separately, as is the See also:

SCREW (O.E. scrue, from O. Fr. escroue, mod. ecrou; ultimate origin uncertain; the word, or a similar one, appears in Teutonic languages, cf. Ger. Schraube, Dan. skrue, but Skeat, following Diaz, finds the origin in Lat. scrobs, a ditch, hole, particularl

screw See also:

shaft See also:

TUNNEL (Fr. tonne!, later tonneau, a diminutive from Low Lat. tonna, tunna, a tun, cask)

tunnel in the See also:

case of steamships propelled by screws.

The tonnage of these spaces is reckoned, not from the tonnage deck, but from the See also:

CROWN

crown of the space; whilst, if it has previously been reckoned in the gross tonnage, there may be an allowance for the space above the crown, if enclosed for the machinery or for the See also:

ADMISSION

admission of See also:

LIGHT

light and See also:

air. Allowances are only made in respect of any machinery space if it be devoted solely to machinery or to light and air. It must not be used for See also:

CARGO (Span. for " loading," from Lat. carries, car)

cargo purposes or for cabins. Further, by the act itself in the case of See also:

PADDLE

paddle steamships, where the machinery space is above 20% and under 30% of the gross tonnage, it is allowed to be reckoned as 37% of such gross tonnage; whilst similarly, in the case of screw steamships, where such machinery space is over 13 % and under 20% of the gross tonnage, it is allowed to be reckoned as 32%. Further deductions are also made in respect of space used solely for the See also:

ACCOMMODATION (Lat. accommodare, to make fit, from ad, to, cum, with, and modus, measure)

accommodation of the See also:

MASTER (Lat. magister, related to tnagis, more, as the corresponding minister is to minus, less; the English form is due partly to the O. Eng. maegister, and partly to O. Fr. maistre, mod. maitre; cf. Du. meester, Ger. Meister, Ital. maestro)

master and the See also:

crew, and for the See also:

CHART (from Lat. carta, charta, a map)

chart-See also:

ROOM

room and See also:

SIGNAL

signal-room, as well as for the See also:

wheel-See also:

house and See also:

CHAIN (through the O. Fr. citable, chcene, &c., from Lat. catena)

chain See also:

cable locker and for the donkey-See also:

engine and See also:

BOILER

boiler, if connected with the main pumps of the ship, and in sailing vessels for the See also:

SAIL

sail locker. The space in the See also:

double bottom and in the water-ballast tanks, if these be not available for the See also:

CARRIAGE

carriage of See also:

FUEL (O. Fr. feuaile, popular Lat. focalia, from focus, hearth, fire)

fuel stores or cargo, is also deducted if it has been reckoned in the gross tonnage in the first instance. From the rules above laid down it follows that it is possible for vessels, if built with a full midship See also:

section, to have a gross registered tonnage considerably below what the actual cubical capacity of the ship would give, whilst in the case of steam tugs of high See also:

POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power it is not unprecedented, owing to the large allowances for machinery and crew spaces, for a vessel to have a registered net tonnage of nil. See also:

SUEZ

Suez See also:

Canal dues being charged on what is practically the registered tonnage (though all deductions permitted by the See also:

BRITISH

British board of trade are not accepted), it is usual, at all events in the British See also:

NAVY

navy, for warships to be measured for what would be their registered tonnage if they were merchant ships, so that in case they may wish to pass through the canal a See also:

scale of See also:

PAYMENT (Fr. paiement, from payer, to pay; Lat. pacare, to appease, pax, peace)

payment may be easily reached. But such tonnage is never spoken of in considering their size relative to other vessels. Two other tonnages are also made use of in connexion with merchant ships, especially when specifications for vessels are being made. The first of these is measurement capacity. This is found by measuring out the true cubic capacity of the holds, whereby it is found what amount of light measurement goods can be carried.

The second is deadweight capacity. This is generally given as excluding what is carried in the coal bunkers, and it is therefore the amount of deadweight which can be carried in the holds at load draught when the vessel is fully charged with coals and stores. (B. W.

End of Article: TONNAGE

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