Three ocean-going tug/barge systems for push towing have been experimentally evaluated for resistance, propulsion, and seakeeping (loads and motions). One employs a completely faired in rigidly connected tug/barge interface; the other two (one single-screw and one twin-screw) employ a pinned joint connection which allows relative pitching between tug and barge. The systems are designed to carry approximately 47,000 tons of cargo using a 3300 BHP medium speed diesel power plant. Propulsion results show the rigidly connected case to have a sea speed of 19 knots while the pinned cases suffer a 1 to 1 1/2 knot loss at the same power. Seakeeping results show all three systems capable of transoceanic service. The rigid connection case is equivalent to a conventional ship and develops its highest connection forces in the vertical direction. The pinned cases relieve vertical forces but accentuate longitudinal forces (to prevent relative yaw). A new computer program has been developed to handle the pinned case vertical force and motion response; its accuracy of prediction has proved to be good. Decoupling of the pinned case is feasible in a moderate seaway, but is not recommended as a design requirement for all conditions. Useful design guidance is provided for the three cases considered, with full discussion of the critical factors and explanation for certain behavior patterns. Extrapolation to other sizes is discussed. Performance differences are such that analytical techniques are inadequate for quantitative assessments, and testing of specific geometries is necessary. Recommendations include further analysis of existing data as well as additional tests of existing models.

  • Supplemental Notes:
    • Four Volumes Set available from NTIS as PB-263535; PC $12.50.
  • Corporate Authors:

    David Taylor Naval Ship R&D Center

    Bethesda, MD  United States  20084
  • Authors:
    • Robinson, J G
  • Publication Date: 1976-5

Media Info

  • Pagination: 94 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00149331
  • Record Type: Publication
  • Source Agency: Maritime Administration
  • Report/Paper Numbers: MA-RD-940-77053 Final Rpt.
  • Contract Numbers: 400-28003
  • Files: TRIS, USDOT
  • Created Date: Apr 13 1977 12:00AM