Small craft - Determination of maximum propulsion power rating using manoeuvring speed - Part 1: Craft with a length of hull less than 8 m (ISO 11592-1:2016); German version EN ISO 11592-1:2016
1Key Takeaways
This part of ISO 11592 specifies requirements for determining the maximum rated propulsion power and maneuvering speed for small motor-driven watercraft with a hull length (H) of less than 8 m (H according to ISO 8666). This part of ISO 11592 does not apply to: personal watercraft according to ISO 13590; canoes and kay…
2Expert Interpretation
This article provides an in-depth interpretation of the ISO 11592-1:2016 standard, detailing the technical requirements for determining maximum propulsion power based on maneuvering speed for small vessels under 8 meters. This includes test procedures, safety standards, marking specifications, and EU directive compliance, offering professional guidance to ship manufacturers and inspection agencies.
Standard Overview and Development Background
ISO 11592-1:2016 is a key technical specification developed by the International Organization for Standardization's Technical Committee for Ships (ISO/TC 188). It replaces the 2001 edition of ISO 11592. This standard specifically targets small motor-driven vessels with a hull length of less than 8 meters. It uses a scientific maneuvering speed test method to determine the maximum propulsion power rating, ensuring the safety and stability of the vessel during high-speed maneuvering.
The technical background for the standard's development stems from the safety risks posed by the increasing power of small, high-speed vessels. With advances in outboard and inboard engine technology, shipbuilders tend to install higher-power propulsion systems, but this can lead to stability issues when turning at high speeds. This standard provides shipbuilders with a scientific method for determining power through a systematic testing procedure.
Scope and important definitions
This standard applies to motorized craft with a hull length (LH) of less than 8 metres, excluding the following types: jet-skis as defined in ISO 13590; canoes and kayaks; inflatable boats as defined in the ISO 6185 series (except rigid inflatable boats reaching speeds of 30 knots or more); racing boats specially designed and built for racing purposes.
Important technical definitions in the standard include:
- Engine manufacturer’s nominal power: the rated power declared by the engine manufacturer in accordance with ISO 8665
- Vessel’s speed: the speed of the vessel relative to the water
- Maximum manoeuvring speed: the maximum speed at which the vessel can safely complete a collision avoidance manoeuvre without losing directional control
Methods for determining maximum propulsion power
The standard specifies two different methods for determining power, which differ depending on the vessel type and propulsion system configuration:
Outboard engine vessels
For vessels equipped with outboard engines, the manufacturer must determine the engine power in accordance with the procedures specified in sections 6 and 7. When the maximum speed vmax ≥ √LH knots (where LH is the hull length), or when vmax > 7√LH knots, the power suitability must be verified by a maneuvering test.
Other types of vessels
For vessels equipped with inboard engines, Z-drives and inboard waterjets, the maximum propulsion power needs to be determined by the tests in sections 5 and 6 and verified by a maneuvering test in section 7 when vmax > 7√LH knots.
| Vessel type | Power determination method | Test requirements | Special provisions |
|---|---|---|---|
| Outboard engine vessel | To be determined by the manufacturer in accordance with the procedures in Sections 6 and 7 | Test is required when vmax ≥ √LH knots | Optional steering wheel or tiller control requires separate testing |
| Inboard engine vessel | To be determined by testing in Sections 5 and 6 | Maneuvering test is required when vmax > 7√LH knots | Multihulls have special stability requirements |
| Z-type drive ships | Tests to be determined in sections 5 and 6 | Maneuvering test is required when vmax > 7√LH knots | Power regulation system requires special attention |
| Water jet propulsion ships | Tests to be determined in sections 5 and 6 | Maneuvering test is required when vmax > 7√LH knots | Maneuvering characteristics require additional verification |
Test conditions and procedure requirements
Ship preparation requirements
The test vessel must be prepared in accordance with the standard requirements: using the maximum engine power installed or planned by the manufacturer; installing a propeller that meets the manufacturer's recommendations; maintaining the specified fuel tank condition (half-full fixed tank, half-full to full portable tank); equipped with the specified steering control system; the engine installed in the lowest vertical position or the recommended position; and the hull, engine, and propeller must be clean.
Test Environmental Conditions
The test must be conducted in calm waters with wind speeds below 5 m/s (10 knots) and maximum wave heights below 0.2 meters. The vessel must be free of any load other than standard equipment, specified fuel, and the operator, who must weigh between 70 and 90 kg.
Speed Determination Method
The maximum speed at full throttle, vmax, must be determined by measuring distances in at least two directions, or by any other suitable and accepted measurement method, with an accuracy within 2% of the true vessel speed or 1 knot, whichever is greater.
Maneuvering Test Procedure and Qualification Standard
The maneuvering test shall be conducted using the collision line test course specified in Appendix A. The vessel shall sail in a straight line at full speed vmax, with the course parallel to and within 5 meters of the lines indicated by Markers A and B.
Test Distance Requirements
For vessels with vmax ≤ 30 knots, the distance from the collision line when commencing turning is d = 6LH; for vessels with vmax > 30 knots, d = 6LH + 2(vmax - 30) meters.
Steering Execution Requirements
When the bow reaches a specific point relative to Marker B, the turning shall be initiated without reducing the fuel supply and without crossing the collision line, and the vessel shall ultimately achieve a course parallel to the collision line. Six complete test runs are required (3 left turns and 3 right turns).
Qualification Standards
A vessel must pass the test if: the operator does not notice any loss of direct maneuverability or stability; the operator has no difficulty maintaining the rudder position; and the vessel does not cross the collision avoidance line.
| Maximum speed (vmax) | Test requirements | Distance from collision line (d) | Handling of test failure |
|---|---|---|---|
| vmax ≤ 7√LH | No | - | - |
| 7√LH < vmax ≤ 30 knots | Yes | 6LH | Reduce rated power and retest |
| vmax > 30 knots | Yes | 6LH + 2(vmax - 30) | Derate power and retest |
Marking and Documentation Requirements
Power Placard
All powered vessels, or vessels intended for power, must have a permanently mounted power placard. The placard must be visible to the operator on outboard-powered vessels and in the cockpit or engine room on inboard-powered, Z-drive, and waterjet-powered vessels. The placard must indicate the maximum propulsion power rating determined in accordance with this standard.
Owner's Manual Requirements
An owner's manual complying with ISO 10240 must be provided on board the vessel, containing at least the following information: a description of the propulsion system and a warning of maneuvering performance limitations; maximum propulsion power rating; prohibition against using engines exceeding the power indicated on the sign; precautions when sailing at high speeds; advice on sailing in congested waters and inclement weather; and reminders of compliance with collision avoidance regulations.
Maneuvering Speed Sign
When a vessel meets the test requirements by reducing speed, a permanent sign indicating the maximum maneuvering speed must be installed within the driver's field of view. The lettering must be at least 5 mm high and the content must be in the language of the country in which the vessel operates.
EU Directive Conformity Analysis
This standard complies with the essential requirements of EU Recreational Craft Directive 2013/53/EU. According to the informative notes in Annex ZA, compliance with Articles 4, 5, 6, and 7 of this standard and Annex A provides a presumption of conformity with the maneuvering performance requirements of Section 4 of Annex I to the Directive.
The requirements for the owner's manual in Article 4.3 and Appendix B of the standard correspond to Section 2.5 of Annex I to the Directive. Although the Directive does not require a power plate, the maximum engine rated power must be stated in the owner's manual.
Manufacturers should note that compliance with this standard does not imply compliance with all applicable EU requirements and directives. In particular, for products that fall within the scope of this standard, there may be other applicable requirements and EU directives.
Technical evolution and standard updates
The main technical evolutions of ISO 11592-1:2016 compared to the 2001 version of the standard include: an update to the standard title to clearly distinguish between different parts; a more precise scope of application; updated normative references; improved terminology and definitions; and more detailed and operational test procedures.
Important technical updates include: a clear definition of the applicability of inflatable boats; the addition of special requirements for multihull vessels; improved eligibility criteria for maneuvering tests; detailed marking and documentation requirements; and enhanced coordination with EU directives.
Implementation Recommendations and Application Guidelines
Implementation Recommendations for Ship Manufacturers
Manufacturers should fully consider the requirements of this standard during the design and production stages: perform power matching calculations during the ship design stage; use the guidelines in Appendix C to determine the initial power of outboard engine vessels; establish a comprehensive test procedure and record system; and ensure that all model variants are properly tested.
Application Guidelines for Testing Agencies
Testing agencies should: establish a test environment and waters that meet the requirements of the standard; use calibrated measuring equipment; train qualified test operators; record test data and results in detail; and provide clear test reports and declarations of conformity.
Regulatory agencies should: pay attention to the compliance of ship power labeling; check the completeness and accuracy of shipowner manuals; supervise the qualifications and capabilities of testing agencies; and refer to the requirements of this standard when handling consumer complaints and safety incidents.
Through the full implementation of this standard, the safety level of small vessels can be effectively improved, operational accidents caused by excessive power can be reduced, and the safety of crew members and other water users can be protected.