scienceillustrated.com.au | 55Huge Hull Glides
Through the Water
Modern technology and ideal weight distribution make huge
ships move through the water with the least possible resistance.
According to Archimedes’ principle,
an object, immersed in water,
has buoyancy related to the water it
displaces. As long as a ship weighs less
than this displaced water, it will float.
The key is density. An iron ball with the
same weight as the ship would displace
less water and so it would sink.Archimedes’ principle
helps titans fl oatThe iron ball sinks, as it
displaces little water
relative to its weight.The ship floats, as it
displaces lots of water
relative to its weight.BUBBLES REDUCE
RESISTANCE
Compressors make air
escape through small holes
in the hull, producing a
layer of bubbles, which
reduce friction between
the hull and the water.BULB PRODUCES
MORE SPEED
Large ships typically
have a bulb right under
their waterlines. The bulb
reduces water resistance,
causing higher speed and
lower fuel consumption.SUPERSTRUCTURE
IS LIGHT
Cruise ships often have
very tall superstructures.
This is possible, because the
upper levels are made of
light materials, whereas
engine and tanks are at the
bottom of the ship.
WATER PUSHES
The water displaced
by the ship produces a
push and so buoyancy,
which counteracts the
downward pressure of the
weight of the vessel.
U SHAPE HULL =
MORE SPACE
As ships have grown,
their hulls have gone
from V to U shape,
providing more space and
making the ship stable
even with less draught.FINS STABILISE
Passenger ship hulls often
have fins, which can be moved
up and down to prevent the ship
from rolling from side to side.Modern cruise ships have
U-shaped hulls, making them more
spacious than V-shaped vessels.STX FRANCE/ROYAL CARIBBEAN INT.SEAWORTHINESSGRAVITYBUOYANCY