This question came up at the shanty sing last Saturday. Sinsull sang the Eddystone Light and then mentioned the version John Roberts does where the mermaid is sitting on a buoy and then goes on to explain that is a channel marker not a juvenile male.

There is a wide range of accents and pronunciations here in the States as elsewhere. I grew up saying boo-ee but lately the word has evolved to something similar to boy-ee.