I am not a sailboat enthusiast but I am interested in how fluid
interacts with the surface
I encountered a brand new 33 ft racer on a trailer in a shop being
readied for water. Looking at the bottom of the hull, I noticed that
the surface in contact with the water had a painted pattern / texture.
(This textured surface may also be protection.
I am sure it can also be smooth and polished if need be.)

It seems that water would be turbulated. Would that not generate more
drag? Is there an other reason why the bottom is textured,
like preventing laminar transition drag?

If the above is true (textured surface), why not have the sides
textured as well, since the boat will be gliding through the water on
its sides for a good part of its racing life? If not true why not have
the bottom as smooth as the sides.
Enquiring mind would like to know.
Udo Rumpf