Overview
ISO 1531:1973 specifies basic terms and definitions related to the hanging of netting for fishing nets. The standard clarifies the principal concepts used when mounting netting to a supporting rope or frame and establishes a consistent way to express the relationship between the length of the supporting rope and the length of the netting, using the hanging ratio (E). ISO 1531:1973 replaces ISO Recommendation R 1531-1970 and complements related vocabulary in ISO 1107.
Key Topics
- Mounting: Attachment of netting to a supporting rope or frame. The direction of the netting relative to the mounting rope (as per ISO 1107) must be stated precisely.
- Hanging: The particular relationship between the length of the final rope or frame section on which the netting is mounted and the length of the netting itself.
- Length of rope: The length of the section of rope or frame between the extreme points where the netting is mounted. When used in the hanging ratio calculation the numerator must be expressed in the same units as the denominator and can be measured in mesh lengths.
- Length of netting: The dimension of the netting to be mounted that is parallel to the final rope or frame, measured when the netting is fully extended prior to being hung.
- Hanging ratio (E): Defined as the ratio of the length of the final rope (numerator) to the length of the netting (denominator):
E = length of rope / length of netting
The ratio may be expressed as a vulgar fraction, a decimal, or a percentage. Example given in the standard: if 10 m of netting is hung on 7 m of rope, E = 7/10 = 0.7 = 70%.
Notes provided in the standard emphasize that any alternative method for calculating percentage must be documented in detail, and that the numerator and denominator must use the same unit of length.
Applications
ISO 1531:1973 is practical for professionals and organizations involved in fishing-net design, manufacture, inspection and regulation. Typical uses include:
- Ensuring consistent specification and communication between designers, manufacturers and clients.
- Standardizing measurement methods for testing, quality control and acceptance checks.
- Supporting regulatory compliance and procurement documentation where precise mounting and hanging definitions are required.
- Assisting technical training and product documentation for netmakers and fisheries engineers.
Related Standards
- ISO 1107 - Fishing nets: netting basic terms and definitions (referenced in ISO 1531 for netting direction and related vocabulary).
- ISO Recommendation R 1531-1970 - The earlier recommendation replaced by ISO 1531:1973.
By adopting the defined terms and the hanging-ratio convention, stakeholders achieve clearer specifications, reproducible measurements, and improved interoperability across fishing-net design and inspection activities.
