With recent and continuing major increase in size of bulk-carrying vessels, the depth of the rivers has become generally inadequate. This is a problem also felt by the coastal ports, but the rivers are typically shallower than the harbors through which they pass into the sea. Cost-of-transportation calculations are made for the shipment of a hypothetical bulk import, in such a way that the cost penalties inflicted by draft limitations are shown. Often, the distance from the sea to a point of receipt may seemingly be a factor, since it obviously increases the length of voyage from the foreign loading point. The same calculations are used to show the effect of river distance, it being assumed that river passage can be accomplished at 10 knots. It is shown that a length handicap is likely to be minor compared to a draft handicap taken independently, when typical instances of each are noted. However, if both are taken together, a draft handicap imposes a multiplying effect on a length handicap. Dredging as a cure for draft handicaps will be more costly for an up-river destination than for a coastal one, simply because of the added distance. An alternative to dredging is the offshore deepwater transfer port, such as proposed for lower Delaware Bay. Calculations are made to show that this would benefit a coastal harbor and a river point in about equal measure. On the other hand, if one looks at a particular site on a river that is too shallow by modern standards, it is seen that the draft handicap is greatly reduced by the availability of a deep-transfer port. This is shown by example of a river, the James of Virginia, where increase in channel depth from 25 feet to 35 feet has recently been denied on the grounds of low benefit/cost ratio.

Media Info

  • Features: Appendices; References;
  • Pagination: p. 67-83

Subject/Index Terms

Filing Info

  • Accession Number: 00054201
  • Record Type: Publication
  • Source Agency: Marine Technology Society
  • Files: TRIS
  • Created Date: May 7 1974 12:00AM