How many letters does the top answer for “a retractable fin keel used on sailboats to prevent drifting to leeward” have?

The most common answer is centerboard (11 letters).

Crossword clue: a retractable fin keel used on sailboats to prevent drifting to leeward

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

centerboard 11 letters wn-def

a retractable fin keel used on sailboats to prevent drifting to leeward

centreboard 11 letters wn-def

a retractable fin keel used on sailboats to prevent drifting to leeward