In calculating the energetics for various conformers of the A, B, and C series of hopanoid hydrocarbons present in mature oil reservoirs, we find that the B series prefers the boat conformation (by 1.3-2.5 kcal/mol) for the D cyclohexane ring (see Figures 1 and 2). We analyze the structural elements responsible for stabilizing this boat conformation, identify the key features, and illustrate how one might stabilize boat conformations of other systems.