Gordon wrote:
What causes some sailboats to hobby horse? Long overhangs? Bow design?
Stern design?
G

I'll start ...

Its a complicated question. For instance, long overhangs reduce
hobby-horsing because they add reserve buoyancy, but they increase it
because of added mass in the extremities.

One design feature that hurts is too much symmetry fore and aft. In
this case there is little change in buoyancy as the boat pitches.

If you have a boat that pitches too much, you can try reducing the
weight in the bow. This is why catamaran owners will avoid heavy
ground tackle, etc.