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There are more yachts than sailing boats in the bay.
Literal
Bay [locative-には] sailing-boat [than-より] yacht [subject-が] many exist.
A comparison sentence. The ~より comparative: 'more than X' is X より [more]. Note that both セーリングボート and ヨット are loanwords, and the distinction the sentence draws (seemingly 'sailing boats vs yachts') doesn't quite make sense in English — in Japanese, ヨット often specifically means a sail boat (any size) rather than a motor yacht, creating an odd contrast with セーリングボート which is more explicitly 'sailing boat'.