Originally Posted by ajdelange
The Arrhenius formula would be the one to use but probably the rule of thumb will get you as good a result as the actual equation given that you don't know activation energies etc. The rule of thumb says that the rate of a reaction doubles for each 10 °C increase in temperature. As you are just about 10 °C shy of 100 °C it would thus seem that doubling the boiling time would get you about the same isomerization.
OTOH you could just use more hops which I guess is what you are doing now. Don't expect any 'clone' to come out dead on. Process and equipment have a lot to do with the nature of the finished product.
Another suggestion would be to wander into a brewpub (of which there are a few in CO per my observation) and ask them how they work around this. I'm just realizing that it never occurred to me to ask that obvious question.
Most of my beers are ones that I just put a recipe together and go with it. With most of the German styles I do, there isn't a super hoppy profile anyway. My issue is with west-coast style IPA's and such. If my options are double the boil or add more hops, does that mean I should double my hops? I usually add a little more than I'm supposed to in clones, just because I like to use whole ounces instead of keeping.28oz for another day. Great idea to just ask a prefessional brewer. I never thought of that. Most of them are down the hill, so their water boils at a higher temperature than at my house, but what a resource I have yet to tap into. I brewed yesterday and the wort only got up to 197F at a vigorous boil. I wonder if atmospheric pressure affects this as well. I hear you on not expecting my "clones" to be spot on. I am a stay at home dad with a lot of time to think about what I can do to make things better and figured that since y'all have been brewing longer than I have, it can't hurt to ask. Thanks to all for responding. I appreciate all your help.