....
Hull speed is not an absolute, it's an approximate calculation and is not very
precise. ...

If it is to have any meaning at all 1.34*sqrt(L) is a decimal
approximation of the velocity at which a wave created by a single
point will have a length L. You can make it as precise as you want.
It doesn't take any particular magic for displacement vessels to
exceed hull speed. A good power to weight ratio is all it really
takes. In the sail boat world most modern racing multi-hulls exceed
hull speed under sail and virtually all of them are pure displacement
craft. Of course, low powered heavy boats like a typical auxiliary
sailing yacht may have top speed to length ratios much less than
1.34.

-- Tom.