[LonePalm]

So for a big tanker or cargo ship, what is the difference of those ratios, in feet?

It is not a question of dimension so much as mass.

A floating object will displace a volume of water equal to the weight of the object.

Colder, saltier water is more dense so less volume will be displaced and the ship will ride higher in the water.

The reverse is true. A ship with the same mass will ride deeper the Gulf of Mexico in summer than it will in the North Atlantic in winter.

The shape of the floating object for a given mass determines its stability and fitness for a given purpose. This is the basis for Naval Architecture.

WWG1WGA

Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)

[ichabod1]

That is really interesting. It had never occurred to me that a vessel rides significantly higher in the winter than in the summer. Would it follow they can also carry more cargo in winter?