The standard yacht is often a hydrodynamic disaster because it hasn't received the time, care, and attention it deserves:
1) The Munk Moment hasn't been calculated or is much larger than estimated
Munk-(Y) (due to yaw/leeway)
Munk-(R) (roll/heel + yaw/leeway)
Munk-(P) (pitch + roll + yaw)
must be considered
2) the hydrodynamic center of a modern keel is located forward (!) of the yacht's center of gravity
3) sailing Downwind crossing an Ocean with Big Waves the bow dips -1°/-2° ... because heel/roll (with "heavy quarters") causes the bow to dip, and because it's carrying tons of lead forward (!) of the pitch axis of rotation ...
and Munk-(P) => 2 x Munk-(R)
If we add to all this ...
4) the orbital current and counter-current of the wave ...
And
5) the slowness of a yacht that only hoist 7-10 square meters per Ton ...
we have an unbearable feedback loop of the three bandits: Roll, Yaw, Pitch