Overview
ISO 14509-3:2009 - Small craft - Airborne sound emitted by powered recreational craft - Part 3 - defines a hybrid calculation + measurement procedure for assessing airborne noise from powered monohull recreational craft (length up to 24 m) with a Froude number > 1.1. It is not applicable to personal watercraft (PWC). The method combines a hull‑form sound prediction with on‑board exhaust measurements to estimate the A‑weighted sound pressure level (25 m pass‑by equivalent) and was developed from the EU‑funded SoundBoat project.
Key topics and technical requirements
- Scope: Monohull recreational craft up to 24 m, Fn > 1.1; excludes PWC.
- Measurement target: Maximum A‑weighted sound pressure level (LpAmax) at 25 m (pass‑by equivalent).
- Hybrid method:
- Hull‑form sound (Annex A) - calculated from hull length and vessel speed using the standard formulae.
- On‑board exhaust sound (Annex B) - measured at seven prescribed microphone positions; derive a logarithmic average (on‑board level LOB).
- Combined using an energy sum (logarithmic addition), e.g.:
LpAmax = 10·log10(10^(LHF/10) + 10^((LOB − T)/10))
where T is a propagation attenuation (16 dB for underwater exhaust; 22 dB for above‑water exhaust).
- Accuracy: Predictive result is stated to be within ±2 dB of the ISO 14509‑1 pass‑by measurement (accounting for measurement uncertainties).
- Instrumentation and procedures:
- Sound level meter to IEC 61672‑1 Class 2; calibrator to IEC 60942 Class 1.
- On‑board spectra: measure A‑weighted equivalent up to the 500 Hz third‑octave band over 10 s at each position; spectra should show clear exhaust harmonic orders.
- Operating conditions: two‑person load (or one‑person craft), full throttle (limited to 70 km/h where applicable), level trim, correct propeller selection per ISO 8665.
Applications and who uses it
- Boat manufacturers and designers for early noise assessment and design validation.
- Acoustic test laboratories and accredited assessors who certify compliance with noise regulations.
- Regulatory compliance: supports conformity assessment for the EU Directive 2003/44/EC (noise limits for recreational craft).
- R&D and product development: provides a reproducible method when full pass‑by testing (ISO 14509‑1) is impractical due to location or weather constraints.
Related standards
ISO 14509‑3:2009 is practical for manufacturers and test labs seeking a validated, reproducible predictive method to estimate airborne sound emissions from powered recreational monohulls.
Open preview (PDF)Small craft — Airborne sound emitted by powered recreational craft — Part 3: Sound assessment using calculation and measurement procedures
