Overview
ISO 13929:2001 specifies minimum requirements for geared link steering systems used on small craft (hull length up to 24 m). It sets construction, installation and test criteria for steering gear that converts steering‑wheel rotation via gearboxes into push/pull motion on the rudder operating lever (the draglink arrangement). The standard excludes remote steering systems already covered by ISO 8848 and ISO 9775.
Key topics and technical requirements
- Scope and definitions - Defines terms such as geared link system, draglink, rudder/rack operating levers and maximum output force.
- Steering rating - Systems must be rated by maximum permissible output torque and corresponding rudder torques at midships and full lock; manufacturer’s rating is used for torque testing.
- Materials and fasteners - Materials must minimize corrosion and galvanic action. All threaded fasteners that affect safe operation require a means of locking (visual/feel verification or integral locking).
- Draglink adjustment and alignment - Draglink shall allow ≥ 20 mm length adjustment and ≥ 15° angular misalignment; securing means must be provided after adjustment. Clevis fittings are permitted only when no angular misalignment exists.
- Lever travel and strength - Rack operating lever must travel no more than 65° from neutral to achieve full rudder travel. Rudder operating lever attachment must withstand 150% of the torque.
- Rudder stops - Stops must prevent exceeding the manufacturer’s maximum rudder angle and resist 150% of the specified maximum output force at full lock.
- Installation - Secure fastening to reinforced structure as needed; remote installations require gearboxes connected by universal joints and solid linkages.
- Tests:
- Axial force test: 670 N applied over any 100 mm span for 10 cycles (≥5 s each) on wheel rim or handgrip.
- Tangential torque test: with rudder shaft fixed and at maximum operating angle, apply 150% of rated maximum output torque for 10 cycles (≥5 s each).
- Marking and documentation - Systems must be marked with the ISO number, manufacturer name and model type. An owner’s manual and an installer’s manual with specified content (ratings, installation and maintenance instructions, exploded parts diagrams, tests, etc.) are required.
Applications and users
ISO 13929 is used by:
- Small craft manufacturers and component suppliers to design and certify geared link steering.
- Naval architects and boatbuilders specifying steering gear for vessels ≤ 24 m.
- Installers and marine technicians performing installation, adjustment and verification.
- Surveyors and regulators assessing steering system safety and compliance.
- Boat owners referencing owner’s and installer’s manuals for safe operation and maintenance.
Relevant keywords: ISO 13929, geared link systems, small craft steering, steering gear standards, draglink, rudder stops, torque test, installation manual.
Related standards
- ISO 8848 - Small craft: remote steering systems.
- ISO 9775 - Remote steering systems for single outboard motors (15–40 kW).