docking vs dockage

docking and dockage both are nouns.

Word	Noun	Adjective	Verb	Adverb
docking	Yes	No	No	No
dockage	Yes	No	No	No

As nouns, docking and dockage are synonyms defined as:

Other synonyms of docking include moorage, tying up.

docking (noun)	dockage (noun)
the act of securing an arriving vessel with ropes	the act of securing an arriving vessel with ropes
	landing in a harbor next to a pier where ships are loaded and unloaded or repaired; may have gates to let water in or out
	a fee charged for a vessel to use a dock