Aristotle Onassis of his fleet, while having trouble managing their own fleets, which operated under US flags and thus at high cost. The high profitability of the Onassis fleet has been attributed in large part to his disregard for standards that normally govern international shipping. For example, after his Liberian registered tanker SS Arrow ran aground and spilled oil into Chedabucto Bay in 1970, still the most significant oil spill off Canada’s East Coast (about 25% of the amount spilled by the Exxon Valdez in Alaska in 1989), there was a Commission of Inquiry. Led by Dr Patrick McTaggart-Cowan, executive director of
Oil tanker instrument, Shell consulted the "London Tanker Brokers’ Panel (LTBP)". At first, they divided the groups as "General Purpose" for tankers under ; "Medium Range" for ships between 25,000 and and "Large Range" for the then-enormous ships that were larger than . The ships became larger during the 1970s, which prompted rescaling. The system was developed for tax reasons as the tax authorities wanted evidence that the internal billing records were correct. Before the New York Mercantile Exchange started trading crude oil futures in 1983, it was difficult to determine the exact price of oil, which could change with every contract.