The following paper reviews both the developmental history and functional concepts underlying the present Sperry Collision Avoidance System (CAS). This system, although invented for very high speed surface effects ships, has been adapted for slower speed ships, thus permitting a degree of safety, maneuvering economy, and ease and speed of decision making which is not possible through other approaches. As the paper notes, two years of sea trials have indicated the success of the system. The paper then reviews the basic concepts of the point-of-possible-collision (PPC) and the predicted-area-of-danger (PAD), both of which are functional concepts in the Sperry CAS. CAS displays of PPC's and PAD's for typical encounter situations are presented. It is shown that the legal constraints (Rules-of-the-Road) are immediately apparent from the display in all situations for which the Rules are defined. It is also noted that the system displays enough information to assure a safe maneuver for situations that are not clearly defined by the Rules, such as the multiple encounter, "nearly end-on," and "in extremis." Based upon these considerations, it is indicated that a computer program that defines the burdened and privileged vessels may be inadvisable. The paper finally discussed the effects of ship dynamics upon the PPC and PAD. Three cases are dealt with: speed changes, turns, and combined turns and speed changes. It is shown that all three cases can be accommodated by simple changes in the position and/or dimensions of the PAD. A discussion of the implications of the limited maneuverability of supertankers upon the maneuvering space as exhibited by the system is included.

  • Supplemental Notes:
    • Presented at Philadelphia Section of the Society of Naval Architects and Marine Engineers
  • Corporate Authors:

    Society of Naval Architects and Marine Engineers

    601 Pavonia Avenue
    Jersey City, NJ  United States  07306-2907
  • Authors:
    • Riggs, R F
  • Publication Date: 1973-2

Subject/Index Terms

Filing Info

  • Accession Number: 00044457
  • Record Type: Publication
  • Source Agency: Society of Naval Architects and Marine Engineers
  • Files: TRIS
  • Created Date: May 23 1973 12:00AM