Deep-Set Hulls Resist Wind; Water Boiling at a Drop
Against Alberti's rule for wind on ships, and a note on turbulent water at a sudden deepening
Leonardo argues that a body sitting deeper in the water is less pushed by the wind, since the wind only strikes the part standing above the surface, and he sets this observation explicitly against Battista Alberti's general rule for how far the wind drives a ship in an hour. A second note, keyed to a pen sketch of churning water, marks a place a b c d e as a sudden deepening where the water falls and boils up. The drawing at the right shows the swirling, foaming water at this drop.
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A deeper-set body is less driven by the wind (against Alberti)
The more a thing is sunk into the water, the less the wind moves it, because the wind acts only on the portion that rises above the surface. Leonardo names Battista Alberti directly as the target, rejecting Alberti's single general rule for how much the wind drives a ship in an hour.
Fall and boiling of water at a sudden deepening a b c d e
A short caption keyed to the sketch marks points b, e, a, d (?) and c, and states that a b c d e is a sudden deepening. It labels the place where the falling water plunges and boils up, matching the churning water in the drawing.