Formula (ex: HP X Prop, etc =MPH)
 

Is there some sort of formula thats out there that will tell me what kind of horsepower one would need to reach a certain speed? Im sure theres too many variables, such as prop slip, boat size, weight, stepped hull, tunnel, x-dimension, etc.. but is there a general rule?

Im looking at a new boat this week and it runs 70ish no problem but curious as to what it would take to get to 90ish

Cale