Originally Posted by TAK
i) Hop utilization is positively correlated with the vigor of the boil.
ii) Hop utilization is positively correlated with the volume of the boil.
iii) Boil-off is positively correlated with the vigor of the boil.
i) is correct, but not at a 1:1 ratio
ii) is not necessarily correct. "Positively correlated" means that one variable increases then the other variable increases. I think what you mean is that for any given mass of solute, hop utilization will increase as you dilute the solute. ie increase your water. Having more volume in your boil wont effect hop utilization, utilization is a function of SG not necessarily volume.
iii)Boil-off volume will decrease your utilization more and more through the boil as your volume decreases but only because your gravity increases; and it is not a linear relationship.
Utilization is calculated by 3 functions.
3. Vigor- this one doesnt effect the utilization as much as the other two but it does have an effect. Some people calculate their IBUs without accounting for the vigor of the boil and thats fine; and some people do.