Convergent Evolution of Boats with Sails

This article unveils the geometric characteristics of boats with sails of many sizes, covering the range 10 2 –10 5 kg. Data from one hundred boat models are collected and tabulated. The data show distinct trends of convergent evolution across the entire range of sizes, namely: (i) the proportionality between beam and draft, (ii) the proportionality between overall boat length and beam, and (iii) the proportionality between mast height and overall boat length. The review shows that the geometric aspect ratios (i)–(iii) are predictable from the physics of evolution toward architectures that offer greater flow access through the medium.