A Survey and Comparison of Criteria for Naval Missions
Final rept. Jan-Sep 1989
DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP HYDROMECHANICS DEPT
Pagination or Media Count:
This report lists which motions and events are commonly thought to limit ship operations. Criteria sets for various Naval missions are given along with their derivation. An annotated list of related literature is also included. The motions of a ship in a seaway can be easily determined using modern strip- theory motion programs, such as the Standard Ship Motion Program SMP84. Subsequent work by McCreight and Stahl incorporate environmental data with strip theory motion predictions to calculate Percent Time of Operability PTO. Calculated PTO values depend very heavily upon the motion criteria used to specify thresholds of unacceptable motion. A significant problem may exist when PTO computations are required because it is difficult to determine the types and magnitudes of acceptable motions for a given ship mission. Furthermore, motion limiting criteria, when specified in open literature, are not always uniformly defined. Degradations in operability can range from mild cases of motion sickness among crew members to serve restrictions on equipment capability. Ship performance degradations arise from habitability, equipment operability, and ship survivability considerations. Habitability refers to crew comfort and personnel requirements. Equipment operability refers to the specific motion limits which affect the operational capability of an individual piece of equipment or machinery system. Survivability is the ability of a ship to survive intact under severe sea conditions. Typically, the motion limits for ship survivability are high enough not to become a limiting factor in day to day operations.
- Marine Engineering