Does Size Matter? Why the crude oil tanker sizes did not increase in last 5 decades?

Recently someone asked me this question as to why there are very few new ULCCs? Why most of the ULCCs were built in 70s ? I considered the question to be a topic of one of my blog. This blog is the answer to that question. Well generally speaking the decision of ordering a particular size of a ship depends upon 1) Technological advancement or feasibility and 2) Economical viability. There are no problems technologically to build largest crude oil tanker of the world never built but the question is “would it be economically viable?” and the answer is NO. The economical viability is again dependent on 1) Costs related to transporting a cargo on a route 2) The demand of the cargo A model of estimated costs to transport per tonne cargo developed from the Evans & Marlow’s model of maritime economics revealed, “ As the route length increases, the larger ships will have lower costs in transporting a unit cargo and there is optimum ship size for a route length”. So for to and fro route length of say 2000 mile, a VLCC would not be an economically viable option but for to and fro route length of 20000 miles, 180000 DWT tanker would be an ideal option. Another factor that affects the ship size is the demand of the cargo and the ships to carry that cargo (Shipping is a derived demand). The unit costs I talked about earlier is bas...