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60 years of design development in tankers and dry bulkers

from 1940 to 2000

Dimitri G. Capaitzis

Piraeus Marine Club, Piraeus, September 2003

During the past 60 years, there has been a spectacular increase in the sizes and efficiency of tankers and dry bulkers.  Improved design has been a key to both developments. A VLCC today carries 300,000 tons cargo at 15 knots on a daily consumption of about 100 tons of fuel oil, while a Word War 2 Liberty carried 10,000 tons at 10 knots on about 25 tons of fuel oil.  This marks a tenfold increase in efficiency.

Welding replaced rivets, while shipyard prefabrication and assembly grew in size, weight and content, with the aid of huge building drydocks, large land and floating cranes, bulldozers, cherry pickers, and other modern machinery.

Progress in metallurgy and steel-making resulted in the replacement of mild steel with  high-tensile steel and the chemical industry contributed with the development of special and longer-lasting paints.

Computers brought great advances in every way imaginable to produce greater strength, stability, safety and efficiency at less cost.  Oil fuel replaced coal; turbines replaced the reciprocating steam engine; water-tube boilers the cylindrical ‘Scotch’ until finally the Diesel engine prevailed.   

The petroleum industry played an important role in establishing the Diesel engine by developing better fuels and lubricants, while advances in engineering made their contributions with bearings, turbochargers, purifiers, etc., and electronics ushered in the age of automation.

With propeller design, large diameters, thin blades, controllable pitch and azipods together with model tests, engine trials and sea trials produced great improvements and greater efficiency.

Loading and discharging were expedited by the introduction of greater cranes, modern hatchcovers, immersion pumps and other innovations, while navigation and telecommunications were greatly assisted by modern equipment, backed up by computers.