Where is the appropriate guidance for substituting synthetic-fiber line for Manila line found?

The appropriate guidance for substituting synthetic-fiber line for Manila line is found in NSTM, chapter 613. This chapter provides specific instructions and standards related to the use and handling of line and rigging, including the characteristics and applications of various types of line, such as synthetic fibers versus traditional natural fibers like Manila. NSTM (Naval Ships' Technical Manual) is a comprehensive source that covers technical information essential for safely and effectively maintaining naval equipment and systems, making it the most relevant reference for this question.

The other sources do not specifically address the technical details or substitutions for line types. US Navy Regulations outline broader rules governing conduct and operations but do not delve into specific technical specifications. Military Handbook 117 provides general information about materials and their uses but may not focus specifically on line substitution. Naval Safety Center Guidelines typically address safety practices and considerations rather than providing detailed material specifications.