The industry position is that a large number of ships are now in service or on firm order between 200,000 to 250,000 t.dw. There is a small number of even larger ships in service or on order, but the large tanker in the immediate future will probably have a length of 1100 ft, beam 160 ft, and draught between 62 and 67 ft. Close co-operation between Port Authorities and interests concerned with the operation of very large tankers is absolutely vital to ensure adequate but economically optimum development of ports. Techniques using single point moorings, entrepot arrangements, lightening at sea, etc. must be expected, however, to have a considerable impact on development of ships' size in the future. To provide a sheltered harbour of adequate depth for large crude carriers, very expensive civil engineering works are generally required, so that offshore tanker terminals are coming more into the limelight. With the mono-mooring type berth the vessel can swing freely around its mooring point, thus taking up the most advantageous position under combined influences of wind, current and sea. The Royal Dutch/Shell Group have made extensive use of their single buoy mooring system. During its eight years of service it has proved to be a workable and reliable berth for tankers up to 100,000 t.dw., even in unsheltered locations. The technical and operational aspects of this system are covered, emphasizing those areas that are of interest to the civil engineer, such as site selection, design of buoy and anchoring system, operational limitations, hose requirements and throughputs. The suitability of the fixed structure for various types of site is considered in relation to the vessel dimensions, types of cargo and the rate of cargo handling required. The design of these structures is considered in relation to vessel size, berthing impacts, mooring forces and service requirements. Some observations are made on the constructional methods and the necessary equipment for building these structures at the speed dictated by modern developments in shipbuilding for the tanker trade. A short historical review of the development of facilities for loading and unloading vessels carrying iron ore is followed by a discussion of the modern trends which influence the choice and design of such facilities, in particular the increase in ship size, the specialization in ship design, and the increase in output of both mines and steelworks. The equipment suitable for loading and discharge at the required rates is described and illustrated by reference to the most recent installations at a number of the more important ore ports. The integration of port facilities and land transport and the relation between these and the stocking policy is also discussed. The categories of the materials and cargoes, other than petroleum and iron ore, moved in bulk are defined and their economic significance in world trade is outlined in respect of the values of the products, and freight, and the vessels and terminals utilized. A forecast is made of the developments to be anticipated and to be sought in the future. The distinctions to be drawn between import and export facilities and between protected (e.g., inside existing harbours) and open-sea situations are emphasized. The advantages and disadvantages of continuous and intermittent bulk-handling methods are considered showing the trend in favour of continuous processes, and the development of self-unloading ships is discussed. Particular facilities for the individual trades described cover grain, coal bauxite, alumina, sugar, phosphate rock, fertilizers, sulphur, timber, copra, etc. The differences arising from 'fluidized' conveying techniques, utilizing pressure differences, and mechanical conveying techniques utilizing gravity are illustrated.

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 10 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00019335
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 8 1974 12:00AM