372

NICHOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE

in a watertight casing connected to the sea below the light load line
a 1-inch sea-cock and vented to the deck, so that, in effect, the balanc
chamber is immersed in the sea at a fixed position relative to the keel

DIMENSIONS OF BALANCE CHAMBER
Be CASING GREATLY EXAGGERATED

\

VENT PIPE?

i AIR PIPE
S if"TO GAUGE
f.-**

?Ai

<wr,»rV<*Vx

•rTiT-p-prr

Fig 14 —Pneumercator Draught Indicators.
In the diagram the head of sea water E is operating the indicator.
Figure 14 shows in profile the lay-out of the pneumercator draught
indicators, the gauges for both fore-and-aft draughts being usually
mounted side by side in any convenient position as selected.
MARKING OF A SHIP.
A ship is required to have in addition to her load line and deck
line marks her name marked on each side of her bows, also her name
and port of registry on her stern. The letters shall be not less than 4
inches in length, and of proportionate breadth. They must be light m
colour on a dark ground, or dark in colour on a light ground. Her official
number and registered tonnage must be cut in on her main beam.
, A scale of feet denoting her draught on each side of her stem and
stern post. The scale may be marked in Roman capital letters or in
figures. The figures must be not less than 6 inches in length. They
are generally made exactly 6 inches in length with a space of 6 inches ,
between them.
The letters or figures must be cut in and painted a light colour
on a dark ground or hi such other way as the Board of Trade approve.
The bottom of the figures indicates an even foot of draught, for example,
the bottom of the 17 feet mark indicates 17 ft. 0 ins.
half way up the 20 feet mark „ 20 3
half way between the 21 and 22 feet marks 21 9
the top of the 24 feet mark indicates 24 6