http://www.realbeer.com/hops/research.htmlIt's more the hops utilization model than BSmith, but BSmith does default to Tinseth's model, and here's a small piece of his numbers. For the same three minute boil-time, utilization in a 1.120 beast would be 50% of a 1.040 bitter (0.015 vs 0.031). I've always been surprised at how little we supposedly get from an additional ten minutes: in a 1.050 wort, going 90 mins from 45 mins only gets an additional 3%.
Decimal Alpha Acid Utilization vs. Boil Time and Wort Original Gravity
Boil OG
Time 1.040 1.050 1.060 1.070 1.090 1.100 1.120
(min)
0 0 0 0 0 0 0 0
3
0.031 0.029 0.026 0.024 0.020 0.018
0.015 6 0.059 0.054 0.049 0.045 0.038 0.035 0.029
9 0.084 0.077 0.070 0.064 0.054 0.049 0.041
12 0.106 0.097 0.088 0.081 0.068 0.062 0.052
15 0.125 0.114 0.105 0.096 0.080 0.073 0.061
30 0.194 0.177 0.162 0.148 0.124 0.113 0.094
36 0.212 0.194 0.177 0.162 0.135 0.124 0.103
45 0.232
0.212 0.194 0.177 0.148 0.135 0.113
54 0.246 0.224 0.205 0.188 0.157 0.143 0.120
60 0.252 0.231 0.211 0.193 0.161 0.147 0.123
70 0.261 0.238 0.218 0.199 0.166 0.152 0.127
80 0.266 0.243 0.222 0.203 0.170 0.155 0.130
90 0.270
0.247 0.226 0.206 0.172 0.157 0.132
120 0.275 0.252 0.230 0.210 0.176 0.161 0.134