What has a lower drag coefficient ... a flat bottom Jon boat or a Zodiak type inflatable?

If your main goal is to find a boat with the lowest drag coefficient I would go with the Kodiak if it has a rigid bottom. If it doesn't then go with the Jon boat. My answer for the Zodiak is based on the rigidity of the hull. If it is rigid hull it will have some what of a vee style design. In the business that's what's known as the "dead rise of the hull". If the boat has a soft bottom, the drag on the motor would be considerably more.