The category "<type_of_ship>" can be expressed as follows:

<type_of_ship>

aircraft carrier

aircraft carriers

amphib

amphibious assault ship

amphibious assault ships

amphibious transport dock

amphibious transport docks

amphibs

arsenal ship

arsenal ships

carrier

carriers

cg

cgs

cruiser

cruisers

dd

dds

destroyer

destroyers

dock landing ship

dock landing ships

g-ship

g-ships

guided missile cruiser

guided missile cruisers

landing craft

landing crafts

lhd

lhds

lpd

lpds

lsd

lsds

ship

ships

ssn

ssns

sub

submarine

submarines

subs

supply ship

supply ships