Another good equation for performance prediction is:

Vb/Vt = 0.4 ((As*L)/W)^0.5

where Vb = velocity of the boat
where Vt = velocity of the wind
Where As = sail area
where L = waterline length
where W = boat weight

just solve for boat velocity...

here is an equation that estimates Vb max....

Vb max = 6.86 ((W*L*y)/(h(0.16*As*L+W)))^0.5

where y = lateral distance from ClaR to CG

Where ClaR = center of lateral resistance

where CG = center of gravity