Church bells could realistically be heard 100 miles away on quiet water.

Evidence

Even without these atmospheric focusing effects, the bells might have been just barely audible at the focal point of the sail aboard a very quiet ship. Given more favorable atmospheric conditions, and favorable position and shape of the sail, there seems to be absolutely no doubt that the ringing of the church bells could have been heard 100 miles away. — Eric J. Heller, Why You Hear What You Hear- An…, 236

Categorization

• CANDY: A vivid, surprising claim about sound traveling a hundred miles across water — easy dinner-party fact.
• QUESTION: This is the payoff of the chapter’s opening scene (the church bells at sea); whether real history supports the 100-mile claim is worth verifying.