Identification of studies Needed to Determine The Feasibility of an Offshore Port
Authors: Bragg Dan M. 
Published: October 2008

If the United States is to remain competitive in world trade, it will be necessary to provide a number of offshore ports along our coasts to accommodate the rising number of VLCCTs (very large crude carriers) and other large ships now in service and under construction in shipyards around the world.

The heavy emphasis on petroleum and petrochemicals in the economy of Texas and the Western Gulf of Mexico makes this area especially sensitive to the need to accommodate the large ships. This paper is a report of a study made concerning the specific requirements for establishing the feasibility and economics of an offshore port in the Texas Gulf region.

Introduction

There has been a considerable amount of discussion and, lately, a lot of publicity, regarding the pros and cons of establishing deep-water berths in United States ports to accommodate vessels whose draft requirements exceed the capabilities of existing channels and harbors. The interest in this subject has resulted from the proliferation in recent years of ocean-going ships built to gigantic proportions, and from the greatly increased water depths required for the safe passage of such vessels. Where the T-2, the standard tanker of World War II, drew slightly over 30 feet of water at full load, some of the larger vessels now in service require as much as 89 feet of water depth. After adding approximately 10 percent more depth to compensate for squat, swells and normal ship motions, required water depths for the largest VLCCTs now approach 100 feet.

The history of water transportation shows that ships have traditionally been designed in accord with existing limitations to free passage throughout the geographical extent of their anticipated voyages. For example, most ocean-going vessels are built with foreknowledge of the restrictions of the Panama Canal. If a vessel is knowingly built with disregard for these restrictions, it is usually because the projected service of the vessel precludes transit through the Panama Canal, such as for instance Great Lakes ore carriers. Sometimes certain desired features of the vessel take precedence over the ability to transit Panama and compensating provisions, such as increased fuel capacity for longer voyages) are designed into the vessel.

Starting with the 1967 closing of the Suez Canal a radical upward trend in ship sizes emerged. Brought on by the combined pressures of excessive voyage lengths between the Persian Gulf and Europe) and demanding schedules resulting from huge volumes of movements and high levels of need) shippers responded by building larger vessels to overcome these problems. Unfortunately) the new vessels were designed with little heed for port capabilities. This difficulty was resolved in the Middle East-Europe service with temporary expediencies quickly developed for the loading or unloading at each end of a voyage. These usually consisted of buoys) anchored in water of adequate depth, connected to storage facilities on shore by pipelines or small feeder vessels. Such installations were compatible at that time with the crisis conditions under which they were installed and with the almost unlimited freedom from pollution-controls existing at the loading and unloading locations.