I own a Newport 33 which has a waterline length of 27 ft. According to
the formula, the theoretical speed for the boat is 6.96 knots.
I have a 16 HP diesel with a 2 bladed impeller, and a maximum engine
RPM of 3300 RPM. Running the engine at 2700 RPM I can readily reach 6.5
knots.
In a good wind I can go to 7 knots. The maximum speed I have ever done
was 11 knots on the GPS surfing down a wave with full sails up on a
very broad reach in about 30 knot wind. Many other boats of the same
design ( relatively light displacemnt, fin keel and spade rudder)
report he same thing.
Racing boats in the around-the world alone race routinely exceeded hull
speed for long periods surfing down waves. The hull speed for a 60 ft
boat is 10.4 knots andthey were achieving more than 20 knots I seem to
remember. So that is the way to go faster than hull speed, find a wave
and then surf down.
Catamarans also go faster than hull speed all the time. So if you put
enough power into the boat in relation to the displacement and wetted
surface, you can exceed the Hull speed.

I think that traditional full keel boat with a high displacement would
have a lot of trouble getting close to Hull speed.
Rolf


Jeff wrote:
However, there are games played with multihulls so that the waves
from
one hull cancel the wave from the other. For one thing, this must be

considered to understand how the chop will slap on the underside.

However, advanced work has been done on more complex configurations
of
three or four hulls with an eye towards high speed and efficiency. I

don't think this has led to any recreational sailboat designs.


Roger Long wrote:
The float would have a hull speed limitation based on it's length.
If
it was shorter than the main hull, it would be a big drag.