376 TSTICHOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE
between F.W. and the dock water (5) is to the difference between F.W.
and S.W, (25)
x ins 5 35
7lS"s=26/'X===26 '
The F.W mark should be 14 inches clear of the waterline, or, the
same result is to submerge the S.W. mark 5*6 inches.
The denominator in inches of the equation is a constant for each
particular ship and the denominator 25 is constant for all ships.
The foregoing methods are near enough for the practical purposes of
loading a ship but it is not strictly accurate for all types of ships, so
the Board of Trade apply the following formula:—
Dxd - ^ u
Immersion = —--------- inches, where
JL X1UUU
D =displacement in salt water up to the centre of the disc
T =tons per inch immersion in salt water at the centre of the disc,
and
d =difference between densities of salt water and the water at the
place of loading
Example.—Caledonian Monarch is loading in dock water (1005), ho^
much may her S W. mark be immersed?
Eeferring to her deadweight scale and supplementary notes at
the end of the book we find total load displacement 13,007 tons; pei
inch immersion 47-1 tons; and by introducing these facts into the
above formula we get
13007X20 . J . ,
Immersion = A7.lxlOQr> - 54 inches
so there is close agreement between the results of the three methods
viz., 5'8, 5'6 and 54 inches respectively.
LOAD LINES.
The Eules of the International Load Line Conference of 1930 have
now been ratified, and are to be effective for a period of five years
when they will be subject to revision and amendment if necessary.
They apply to all countries of maritime importance. Specific rules
regarding the positions of the various load lines are given for a standard
ship of certain dimensions and superstructures with further modifi-
cations for vessels which depart from the standard ship in certain
particulars. '