Because I do actually find this discussion interesting (to a point), since you have this interest in ship design, I see two worlds in the modern profession.
Mega/super sized, where you're transporting X for the cheapest 0.00000Y-cent (before taking into account foreign currency exchange markets....) from A to B or C. This falls into the niche of specialty designs, much like oil drilling barges/platforms, you don't build many of them in the world, but you build a few of these very specialized (often behemoth-sized) vessels (even the mega oil tankers have a lot more to them than just an oversized bathtub).
Or trying to get X+1 into given maximum dimensions for the canals/channels/gates you have to fit your vessel to get through.
Now, maybe, perhaps this will light up a bulb in your head as to why our (-capitalist consuming Americans) ports (as well as the exporting markets of asia, the philippines, and the west-half of south america are dependent on our nation's West Coast ports - which in turn have developed into some of the largest (size, cargo volume and individual ship sizes) in the nation and world. Hypotheticly, lets say Honda can send a ship with 5,000 cars to Port Hueneme or Los Angeles here in CA (or even Washington State or Frisco or... well you get the idea) in one fell swoop, hire a bunch of American truckers (and Honda PR lights another cigar) and maybe a contract with a couple large railway companies (American companies/union work) and still save more money than shipping 10x500-car shipments through panama on the way to the eastern-half of our nation.
Same example can be made with the mega tankers and the oil industry, the wells in the mid-east, refineries located along the coast from Texas to Maine, the Suez Canal (which given recent history, they've been really interested in leaning away from depending on - enter the boon of mega-tankers in the last decade or two as the demand is still strong), etc.. Cheaper to avoid that whole mess, take the scenic route around Africa, and deliver a mega-tanker full once every few weeks or so "straight" from Dubai to Galveston. It's all dollars and cents.
