Neil, a flat bottomed boat will demonstrate more initial stability than a vee or semi-rounded bottom. It feels more stable and resists leaning. BUT, when the lean reaches its limit, the boat suddenly breaks and flips.
A semi-rounded bottom shows less initial stability, but more secondary stability, especially if the sides are flared. Another characteristic of a semi-rounded bottom is how they ride while in waves.
As waves flow along under a boat, they effect the boat. A flat bottomed boat will, by necessity, roll as the flat bottom matches the angles of the passing wave. The flat bottom rolls to match the approaching angle of the leading edge, roll back to level as the crest passes under, and continue to roll to the opposite side as the trailing edge of the wave pases along. With a semi-rounded bottom boat will simply bob up and tnen back down as the a wave rolls along underneath. The difference is that, the rounded bottom always has an angle to match any angle presented by the front, crest, and trailing edges..
All boats react to waves somehow, The dock will remain stable.