[en] Within the next ten years, three significant events will affect the structure of tankering costs for the Alaska North Slope (ANS) oil fields. These are: the double hulling requirement of the Oil Spill Pollution Act of 1990 (OPA90); the ageing of the tanker fleet; and the decline in ANS and West Coast oil production, which will eliminate more costly shipments to the Gulf Coast. The purpose of this paper is to estimate how these will affect tankering costs over the next twenty years. As baseline, the existing fleet is described, followed by a detailed discussion of the above factors. Company specific shipping requirements are calculated as compared to ship-by-ship tonnage availability (based on the current fleet) pursuant to these events, and the resultant tonnage deficit. A model is presented that derives a hypothetical reconstruction scheme to eliminate the deficits on a company specific ship-by-ship basis. The resulting costs are then translated into a weighted average per barrel ANS cost. The specific double hull costs are segregated. (author)