ISO 13342:1995

Overview

ISO 13342:1995 is an international standard developed by the International Organization for Standardization (ISO) that specifies a standardized method for measuring the static thrust of outboard motors on small craft. This method focuses on accurately evaluating both forward and reverse thrust produced by outboard propulsion systems while stationary. The standard plays a critical role in determining the necessity of start-in-gear protection systems for safety compliance, as outlined in ISO 11547.

By providing a consistent procedure for thrust measurement, ISO 13342:1995 ensures manufacturers and regulatory bodies can rely on robust, reproducible data to validate motor performance and safety features.

Key Topics

• Static Thrust Definition
  Static thrust is defined as the horizontal force an outboard motor can produce while the vessel is stationary, measured in newtons.

• Test Conditions

  • Conducted in still water between sea level and 250 m altitude
  • Minimum water depth must be four times the propeller diameter
  • Clear flow area of 3 meters in front of and behind the propeller, with no obstructions to prevent ventilation or cavitation effects

• Test Equipment and Setup

  • Thrust force measured with a calibrated gauge/transducer accurate to within ±2% of maximum thrust
  • Motor must be representative of manufacturer’s production units and run-in as per manufacturer’s specifications
  • Modifications allowed only when following a manufacturer’s approved modification kit
  • Propeller shaft and measuring device aligned parallel to water surface within ±5 degrees

• Data Declaration

  • Forward and reverse thrust values at various throttle settings declared without correction factors
  • Declaration includes propeller diameter, pitch, part number, and modification kit details if applicable
  • Average values used for reverse thrust due to fluctuations caused by exhaust ventilation

Applications

ISO 13342:1995 serves multiple practical purposes in the maritime industry, particularly for:

• Outboard Motor Manufacturers
  Ensures consistent, verifiable thrust performance data for product declarations and compliance testing. Helps manufacturers determine if start-in-gear protection devices are necessary to meet safety regulations.

• Regulatory Agencies
  Facilitates a standardized measurement approach enabling reliable safety certification and enforcement of propulsion system standards on small craft.

• Boat Builders and Designers
  Assists in selecting appropriate outboard motors based on verified thrust capabilities, influencing vessel handling and propulsion system integration.

• Safety and Compliance Testing Facilities
  Provides a clear, replicable method for testing thrust that supports compliance with related standards such as ISO 11547 for start-in-gear protection.

Related Standards

• ISO 11547:1994 - Small craft - Start-in-gear protection
  Defines requirements for protective systems preventing accidental engine engagement while in gear. ISO 13342 thrust measurements help determine when this protection must be implemented.

• IEC Standards for Electrotechnical Equipment
  Given ISO’s collaboration with the International Electrotechnical Commission (IEC), related electrical safety and performance standards may complement the mechanical thrust testing specified in ISO 13342.

• Propulsion System Performance and Safety Standards
  Other ISO and industry-specific standards for engine emissions, noise, and vibration assessments are relevant in comprehensive outboard motor evaluations.

Keywords: ISO 13342, static thrust measurement, outboard motors, small craft propulsion, start-in-gear protection, marine engine testing, thrust force measurement, propeller testing, maritime safety standards, ISO 11547 compliance.