The Ghillie Kettle is a double walled boiler with a chimney running up through the centre. Once filled with water, put the whistle cap on and build a small fire in the base. Add fuel by dropping it down the chimney. The heat transfer from the large surface area of the chimney quickly heats the water and with a bit of practice, you’ll have a nice rolling boil in about 4-5 minutes, in nearly all weather conditions.