An early game craft that cannot carry armor, but does not require fuel. It requires wool as sails to be able to move. It will sink after losing 50% of its total tonnage. In general, it travels slower than powered craft types. It can be as small as 10 blocks or as large as 8000.
A naval vessel that can be armored. They can only travel in water. This craft will sink when 50% of its tonnage is destroyed. They can direct fireballs and TNT. Classifications include:
Smallships which can be as small as 10 blocks or as big as 3000.
Ships (3000-8000 blocks)
For every block of hull above water, a watercraft must have one block below water; this applies to all water ships. Superstructure, rigging, turrets, sails do not count as hull. This rule will eventually be replaced in favor of a buoyancy-based system.
A small unarmored craft that is very fast and burns a lot of fuel for its engine size. 100 blocks max size. These can direct fireballs, have a 50% lift requirement, and will sink when more than 40% of its tonnage is destroyed.
A small strike skiff out on patrol, courtesy of Yguy9
A mid-sized airship seen navigating a treacherous thunderstorm, courtesy of ShowingCards
A large flying vehicle that can be armored and direct TNT and fireballs. It must be 45% wool in order to fly, losing more than 40% of its tonnage will cause it to sink. It can be as small as 100 and as large as 40000 blocks across all subtypes.
Classifications:
Airship: Between 100 and 5000 blocks in size.
MediumAirship: Between 5000 and 1000 blocks in size.
BigAirship: Between 10000 and 20000 blocks in size.
MegaAirship: Between 20000 and 40000 blocks in size.
Submarine: A craft that moves primarily underwater, and can be armored. They can direct fireballs and TNT. They require prismarine to be able to dissipate heat underwater. They can be as large or as small as their airship counterparts. They will sink when 40% of their tonnage is destroyed.
SubAirships: All airships have submersible variants.
A submersible airship waiting for prey to carelessly enter weapons range, courtesy of DukeOfAveline
Vehicles are ground-based craft that can be armored, in addition to directing fireballs and TNT. It can be as small as 10 blocks or as large as 1000. They require little fuel relative to other craft types. They require 5% black wool as tires connected to the ground in order to move. This craft will sink when 50% of its tonnage is destroyed.
You can put diamond blocks as drills on Vehicles and Submarines. Diamond blocks are very heavy and require large engines to move, so take that into account for your designs. These can mine through most ores and stones you find naturally.