Overview
ISO 484-2:2015 - "Shipbuilding - Ship screw propellers - Manufacturing tolerances - Part 2" - specifies manufacturing tolerances for ship screw propellers with a diameter between 0.80 m and 2.50 m inclusive. The standard defines measurement methods, accuracy classes, and numerical tolerance limits for pitch, blade thickness, extreme radius, form and contour, surface finish and static balancing. It also notes that some deviations may be permitted by agreement between the customer and designer.
Keywords: ISO 484-2:2015, ship screw propellers, manufacturing tolerances, propeller pitch, blade thickness, propeller radius.
Key topics and technical requirements
- Scope and applicability: Applies to monobloc, built-up and controllable pitch propellers within the 0.80–2.50 m diameter range.
- Accuracy classes: Four classes - S (very high), I (high), II (medium), III (wide tolerances). The customer selects the class.
- Pitch measurement methods:
- Marking gauges
- Graduated ring method
- Coordinate measuring machine (CMM) using Cartesian or polar coordinates
- Pitch tolerances: Specified as percentages of design pitch and minimum absolute values for:
- Local pitch, mean pitch per radius, mean pitch per blade, and mean pitch for the entire propeller (Table values depend on accuracy class).
- Radius & thickness tolerances:
- Extreme radius tolerances given as % of radius with minimum mm values.
- Blade thickness tolerances (plus/minus) expressed as % of local thickness with minimum absolute values; measurements taken at the same radii used for pitch checks.
- Form, contour and edges:
- Templates or equivalent checks for leading/trailing edges and cylindrical sections (stricter limits for classes S and I).
- Rules to limit cumulative deviations (e.g., algebraic sum constraints on consecutive local pitch deviations).
- Other requirements:
- Surface finish indication (referenced ISO 1302)
- Static balancing (referenced ISO 1940-1)
- Measurement equipment and verification procedures
Applications and users
Who uses ISO 484-2:2015:
- Propeller manufacturers and CNC machining shops
- Shipyards and marine equipment suppliers
- Naval architects, marine engineers and propeller designers
- Classification societies and surveyors
- Procurement teams specifying acceptance tolerances
Practical uses:
- Define acceptance criteria for manufactured propellers
- Guide inspection and measurement procedures (CMM, templates, ring gauges)
- Support contractual agreements on accuracy class and permissible deviations
- Ensure compliance with classification society requirements for thickness and balance
Related standards
- ISO 484-1 (Part 1 - propellers > 2.50 m)
- Normative references: ISO 1302 (surface texture) and ISO 1940-1 (balance quality requirements)
For specification and inspection workflows, reference ISO 484-2:2015 when defining manufacturing tolerances and measurement protocols for small to medium-sized ship screw propellers.