Acoustic emission intensity of an unmotored sailboat will equal that of a motored boat at ~12 Knots. At ~15 Knots, the sailboat will be ~2x ‘louder’. The intensity increases exponentially with speed
Caveat: I am not a marine biologist and have no qualification, authority, or credibility on this topic. This is a hypothesis for contemplation / discussion.
The Noise Imperative: Why Orcas Are Sinking Sailboats