Encyclopaedia Britannica > Volume 21, ROT-Siam

h.w'lomettinj t” ?pla“' wScifSouiablwitltompSt,!?1*0? ,ho“M
all her weights properly secured nud *1,,, e sar.1?f seasi but one having
traversing the deckPevery time the shi^roUs^ If^he t Jo6’81^ ?apable of
ro 1 to exactly tlje same extent we should have the let I f Venssels„were to
slnp with the loose weight to the same £
SHIPBUILDING
815
Dynami
cal
Fig. 7.
IlISlIiigsissHSs
ssssssi-sMliSs
ho^nati!Cal^tarlllty Is the “.work ” done or energy expended in
stability n, fr0I,rl tke. uPright to any inclined position. The
^ ton* AVhen^bl™1’0^'- m ra(fSn''in" dynamical stability is a foot-
ton. When the vessel is gradually inclined the forces inclining
StahiUtw+L W°rk <?epen< lng uPon tlle amount of the statical
aS IS a he SUCCeS'lV'° tantaneous inclinations passed through,
and these are given by the curve of stabilitv already described
Dynamical stability is of value as a means of comparing X
InnliVrTf °f ShlpS i° upsettlng under the action of suddenly
Mfwhite s^ys:- “ SqUalIS °f Illustrating this
“ Roughly speaking it may be said that a force of wind which
ef^-d continuously applied, will heel a ship of ordinary form
to a certain angle will, if it strikes her suddenly when she is
caPsresgfurthrerVest ]ir T t0 if twi?e tPat inclination, or in some
cases turther still A parallel case is that of a spiral spring • if a
weight be suddenly brought to bear upon it, theextensTon will be
lwntW1CeiiaSrgrfl althat t0 whicl1 the same weight hanging
»hWlllhS retch !he- Spring- The explanation is simple8
When the whole weight is suddenly brought to bear upon the
u^tlf’thf6!^818^06 vhich the sl,ring can offer at each Instant,
wmVbf*^ time W 1611 AtS pension supplies a force equal to the
storlsVn wlVrlyS “ the We1ight ’ and this unbalanced force
doubles TheWhich carries the weight onwards, and about
when at rest.,?t °f he Spnng corresP°nding to that weight
Structure.
The changes which have come about in materials and modes of
ThXret10sntelX\th-l+laSt 50 };earS llaVe been most remarkable.
U rnnp f I *? - built exPressI7 for regular voyages between
' at about thisX^^^W u0t 'built UIltil 1837‘ I)r Ladner stated
at about this date : We have as an extreme limit of a steamer’s
reat 2000* mlhs without receiving a relay of coals, a run of about
• , ^000 miles. The Great Western, built bv Patterson of Hristef
s era. and engined by Maudslay of London under the superintendence of
19 1JW Brqpe1’ WaSo?oe frSt ?Uch Sbip’ and sbe was launched July
feeVlD. L S^e was 212. ^et long between the perpendiculars, 35
nrn*utl WlhLS bl’0 u i and fad a displacement of 2300 tons. She was
?entn! f Jy paddles-. ^mi vessc]s were built early in the present
sm vW7 for.failal seiwice, then for river service, and later for packet
dimX™ the coa1sts; In about the year 1838 iron vessels of small
p -i, ,s wemhudt for ocean service. The largest iron vessel
built up to 1841 was less than 200 feet long. In 1843 we get for
tne nrst time the ocean-going steamship in its present form, built
of non,” and propelled by the screw. This was the “ Great
i in tain, 486 feet long, projected and designed by Brunei. Time
has abundantly justified these bold enterprises on the part of
lune , wiucli he had to carry through in the face of great opposi-
,1 *i.n' . 6 entered with equal boldness on another innovation in
ooO, viz., the use of very large dimensions on the ground of
economy of power. It was not until 1852 that he had the oppor-
Grett
No. Lenoth ...... 1 “ ~ Eastern.
w: 680
indicated horse-power 4 000 and ™L-25i fft ’ SCrew enSme>
paddle, indicated horse-power 2 600 and l horse-power, 1600;
1,000; to work with steam 15 R to *25 ft nomipal horse-power,
55 revolutions ; paddle 10 to 12 5 ^ ’ Speed °f SCreW’ 45 to
r ~
oir Se£ large ship
which would be hu d t', receive ptll0Ht inconvenience a wound
obtaining high speSt^e Z T^wted
thl^uto'fVeihi ?rea‘ Ea,S‘r-” “ migl“ aWfte
building Uself h y’ and d'aDged aIso historI »f sbip-
The question of bulkheads, on which Brunei insisted so much in u u
I^nSberoTlSf rderli!? “11 oT'liZZ ithe"!'
tne number of bulkheads m ships were increased as thev ouuht to
^moXeflnd^X0* oAKi^tX
oe moained, and the system of construction general] v would be
changed, and become more like that of the “ Great Eastern’’ The
so thaUtmivbeT °T Thich justifies some further consideration,
so mat it may be popularly understood.
outTwater8 CO“mon1/ m!ld\ with less than half their bulk
out of water. If water enters such a ship, and the amount which
which ?s°outnof lU buVbat Portion of the bulk of the ship
Sc i/cr +Ln A"6 water’.«?l^ when immersed, exclude
the water, then the ship, if she does not turn over, will still float
soon slnks^ ^ infl°W Cannot be stoPPed> but continues, the ship
fOL^Sd^Pr0-?16! Casr °l a sbiP 50 feet long. 10 feet wide, and
10 feet deep divided into five equal parts by four watertight par¬
titions, and floating m water with half its bulk immersed (fig18)
Suppose now that a v 6 '
hole is made in the
middle of this ship
under the water, so
that water can flow
freely in, then the
part of _ the ship
which is shaded Fig. 8.
eat
itain
ceases to have floating power. The water in this shaded place is no
th pS!wldlSplaCe+d’ Imi18 ad“ltted’ and if the ship is to continue afloat,
Which BG Ph l df nhlp mUS,t disPlace water to the amount by
w hich this shaded part has ceased to do so. As it is one-fifth of the
whole immersed bulk which is lost, the remaining four compart-
wAYT S11£iS° as1each to suPPort one-fourth of the whole,
instead of one-fifth as before ; i.e., the draught of water, or im¬
mersion of the whole ship, will be increased, and the ship will if
she has stability enough to keep upright, finally float at rest again
at this deeper immersion. The water will rise in the centre com¬
partment to the level of the water outside, and will then cease to
How in _ The additional immersion will be only one and a quarter
feet, but m an ordinary ship, divided into compartments of equal
length, there would be a greater increase of immersion by the iniurv
of a centre compartment, because the end compartments are narrow
and must sink deeper in order to bear their share of the burden
imposed by the loss of the buoyancy of the centre division.
Or it may be other than a central compartment which is
damaged, and in that case the ship tips, and finds a new floating
line, with the end towards which the damaged division lies
depressed more than the other end.
If it should happen that the divisional partitions, or bulkheads
aS, t !ey are ,called’ nse onl}7 a few inches above the water level
which the ship floats at when undamaged, then, on the occur¬
rence of a bad leak filling one compartment, the tops of the bulk¬
heads are brought, by the increased immersion of the ship beneath
the water-level the water will rise through the hatches,’or open¬
ings in the deck, in the damaged compartment, will flow over the
entire deck, and the ship will be lost, either by the filling of other
compartments by the water passing down into them, or by the
capsmng of the ship. This latter event will generally happen
although only one compartment is full, if the sea has free access to