According to Toronto police, the man was aboard a seven-metre-long sailboat on Sunday that was equipped with a small outboard engine.
Police say he was travelling north on Blockhouse Bay, when he ended up striking another boat that was docked in the harbour.
The man fell into the water.
The marine unit found the 60-year-old man swimming to shore.
He was subsequently charged with two impaired-driving counts. Police have seized his sailboat.