I've been using the Dinwiddie Ring Method for a couple of weeks now, and I really like it. My confidence level has really shot up, and my dutch oven cooking has become MUCH less stressful. I really wish I would have known about this method sooner. I have 6 or 7 dutch oven cookbooks, and they all use coal counting. I haven't seen one yet that teaches this method. I wonder why that is?
First, let me tell you why I like the ring method over coal counting. With the ring method, I can use any brand of charcoal on the market. (Even Kingsford, which I have also been using with great success for the past few weeks.) I can even mix brands of charcoal with out any problems. I can also use any size of charcoal without having to compensate for the size differences between brands. For instance, I had been using Sam's Choice brand charcoal for most of the year. It is twice as big as Kingsford charcoal and therefore puts out more heat and burns longer than Kingsford. If I'm using 20 Kingsford briquettes, they are putting out less heat than 20 Sam's coals. But with the ring method, I don't have to compensate for any of that.
I know you have all seen the Lodge Temperature Control Chart. It is really complicated and I couldn't cook without consulting the chart to see how many coals I needed. The Dinwiddie Method's chart is much easier to remember and I don't have to check it before I cook every time.
1 ring: If you make a circle of hot charcoal with all of the briquettes lying flat and touching each other, with spaces left out for the legs on the bottom rings, that is "one ring". The outside edge of the ring is lined up with the outside edge of the pot, top or bottom. For the record, I still use the coal counting method for the bottom heat. I take the size of the oven, subtract 2 and that is the number of bottom coals I use. I've found that if I use a full ring on the bottom I tend to burn my food.
1/2 ring: A "half ring" is the same size circle but with every other briquette missing.
2 rings: is simply a second ring just inside the first, with the rings touching.
Full spread: Means to put all the briquettes you can (one layer deep, lying flat) either under or on top of the pot.
The ring method is self correcting for the size of the briquettes used. If your charcoal has been burning a while, the pieces will be smaller and will put out less heat. But it will take more of them to make a ring, so you still get about the same temperature. As the briquettes burn down, you simply add more to fill in the spaces and keep the temperature constant.
Duane Dinwiddie found that he could cook almost everything there is with just four temperatures--slow, medium, hot and very hot. For a 12" dutch oven, slow will have 1 ring on top and one ring on the bottom and be 300* (+/- 25*). Medium is 1 ring under and 1 1/2 rings on top and is 350* (+/-25*). A hot oven is 1 ring under and 2 rings on top and is 400* (+/-25*). A very hot oven is 1 ring under and 2 1/2 rings on top and is 450* to 500*(+/-25*).
The following chart shows this method in detail.