You should better let us know a bit more.Mainly boat´s size (small may vary from one person to another, from 6 to 12 m ?)
Max speed, as it give pressure on the hull when striking the waves and so the stresses criterion for calculations..
Type of construction, sandwich, solid, exotics, glass.
Long time ago there was a thumb rule for solid hulls: 1 mm thickness per hull´s meter long. (10 m => 10 mm)
Now everything is better known and understood, allowing
A general use is to alternate woven roving and CSM as CSM ir resin rich and assurees a good interface between w roving
Cutting a sample or drill to builld same thickness is a good starting point.
Also depending on hull´s area, stresses vary a lot, from low on the sides to very high on the slamming area (where it hits the waves)
Same for local stresses, specially on sandwich construction, as core may collapse and may be substitued by high density, wood or even solid.....
If high spped, the hull can also hit truncks or any other floating object, and kevlar is often choosed for outer layers.....
A 30 Knots 12 m boat solid laminate had about 8 mm skin with a panel size of about 1,0 x 0,5 m
Panel size is vital ...........
Is a wide field .......