Okay, that’s awfully vague, I know. See, the thing is that I have very little clue how sizes compare between things like oil tankers, cruise ships, aircraft carriers, submarines, and I suppose other cargo ships as well. What are typical sizes? What’s the biggest ship there is? How do they compare to buildings on land?
They can be pretty damned big.
Nimitz-class aircraft carriers, the largest warships in the world, are 1,092 feet long and displace 97,000 tons of water.
Very Large Crude Carriers (VLCCs), also known as supertankers, can carry up to 250,000 tons of oil.
Bulk cargo carriers can carry up to 200,000 tons of cargo.
The largest ship in the world is still the Knock Nevis, launched in 1981. It’s 1,504 feet long and weighs 647,955 tons when fully laden.
Googling, or browsing on Wikipedia.org, will give you a lot more info.
Above the VLCC, are the ULCC - Ultra Large Cruise Carriers. These have a length of approximately 415 meters, a width of 63 meters, and a draft of 35 meters. To place this in scale to a Michigan landmark, the central span of the Ambassador Bridge connecting Detroit and Windsor is 564 meters long and rises 46 meters above the Detroit River.
There’s also a set of dimensions called panamax - the largest that can pass through the Panama Canal.
If someone wants to build a larger ship, they’re certainly free to do so, (and will be considered “post-panamax” but they’ll have to find another way to get between the Atlantic and Pacific. Not a problem for tankers or cargo ships whose only intended route is say, China to Long Beach.
Modern ship size definitions courtesy of Lloyds Register.
For comparison, typical displacements for modern U.S. submarines range from 6,900 tons (submerged) for a Los Angeles-class fast attack submarine to around 18,000 tons for an Ohio-class “Trident” ballistic missile submarine.
Here is a site that is mostly about starship dimensions, but they have the Yamato, the Knock Navis/Jahre Viking and a Typhoon class submarine compared to many other objects (on the bottom of the “1X” page.)
Passenger cruise ships seem to run between 700 and 1000 feet. The largest liners of the old days were well over 1000’ in length; the contemporary QEII might also be.
Ultra Large Crude Carriers