sliding keel vs drop keel

sliding keel and drop keel both are nouns.

Word	Noun	Adjective	Verb	Adverb
sliding keel	Yes	No	No	No
drop keel	Yes	No	No	No

As nouns, sliding keel and drop keel are synonyms defined as:

sliding keel and drop keel: a retractable fin keel used on sailboats to prevent drifting to leeward

Other synonyms of sliding keel include centerboard, centreboard.

sliding keel (noun)	drop keel (noun)
a retractable fin keel used on sailboats to prevent drifting to leeward	a retractable fin keel used on sailboats to prevent drifting to leeward