I understand, from "How to Brew", that many adjuncts (I'm especially thinking oatmeal here, for a porter) require mashing with an enzymatic base malt to become fermentable. My question is, what's an appropriate ratio of base malt to oatmeal, given that I'm only doing a partial mash rather than an all-grain batch? I don't recall seeing this info anywhere; if there's an online calculator or guide somewhere, link away...