THE HISTORY OF THE SUBMARINE
Normally a submarine is a military vehicle and
a submersible is a civil machine. The first seagoing submarine was
built in 1879 by the Reverend Garett and was called the Resurgent.
The first true submersible was probably the Turtle which was built
in 1776 by a David Bushnalls. It was used by the Americans to attack
the British Fleet in New York harbour. There were probably previous
attempts before 1776 by people trying to make submersibles, but
most of the activities prior to this date involved using upturned
wooden or leather buckets, with compressed air being forced down
to the divers by various mechanisms.
FIRST ROYAL NAVY SUBMARINE
The first Royal Navy submarine was the Holland
built in 1901 which carried 8 people. Today the present Trident
submarines are 150M long, 3 times the height of Nelsons Column,
and are powered by nuclear energy and have a displacement of 15000
tonnes. The Polaris submarines of the Royal Navy are somewhat smaller,
but still displace 8500 tonnes and are capable of speeds of up to
30 knots. To propel a vehicle through the water at this speed takes
tremendous energy. The typical electrical output of a Polaris submarine
is sufficient to power a town.
Modern day submersibles are very special pieces
of machinery, and those that go to extreme depths to explore the
seabed where the Titanic lies are few in number. There are probably
only 3 vehicles today that could reach such depths. ‘Alvin’ from
Woods Hole Institute in the USA is one of them. There is also a
French vehicle ‘Nautile’ and a Russian vehicle ‘Mir’ capable of
descending the 2.5 miles to the Titanic.
A large portion of underwater exploration and inspection
today is carried out by ROVs (Remote Operation Vehicle). These devices
help overcome many of the problems which restrict human activity
below the sea. Although these vehicles are very expensive and do
get lost occasionally, their use is a safer approach than sending
divers in to do the same jobs, by avoiding the increased human vulnerability
and minimizing risk. Submarines and Submersibles often combine the
ability to perform tasks underwater as ROVs and shelter humans from
many of the conditions faced by divers, allowing humans to explore
their underwater subjects in proximity and in safety.
Gemini is a recreational vehicle and has a depth
range of 50M. Even at this depth the pressure on the hatches is
about 14 tonnes, and the total pressure on the pressure vessel itself
is about 125 tonnes. It has all the components of a large submersible,
namely – surface buoyancy tanks, trim tanks, lead trim, lead acid
batteries, life support systems, front and rear hydroplanes, a rudder
and a very sophisticated control system consisting of a PLC (Programmable
Logic Controller) and many electrically operated solenoid valves,
pneumatic actuators, stepper motors, encoders and several electrical
power systems. Its forward speed is 4-6 knots and when the surface
buoyancy tanks are fully blown, it has a freeboard of 300-400mm.
The design and control of the submersible combines just about every
engineering discipline i.e. structural, electrical, mechanical,
life support, physics, hydrodynamics and naval architecture.
Aquarius is Subeo’s production submersible,
details and specification can be viewed on this site.