Reading through Rival Magic p58, the spell “We’ve confidence in the waves, and the winds grant us calm seas” mentions another spell "Break the Stormy Sea". I don't see it listed in the book. Perhaps I'm missing it. I wouldn't doubt it. Is this listed anywhere or is this another case figure out the obvious spell yourself?
I'm guessing it was the original name of "It is best now to calm the raging waves" on page 59. One wards against the wind, one against the sea; so long as the ship is stationary via an anchor or some such.
I would say that manamar nailed it. Spell names and similar things can change quite a lot during the development of an ars supplement. Seems they oversaw this reference when changing it.