ISO 22834:2022

Overview

ISO 22834:2022 - "Large yachts - Quality assessment of life onboard - Stabilization and sea keeping" establishes an objective, comparative scale for motion-related comfort on large yachts. The standard defines a 5‑star rating (no judgement) tied to measured motion metrics, enabling technical and commercial comparison of yachts, evaluation of stabilization systems, design comparison and identification of the most comfortable positions onboard.

Key technical topics and requirements

• Primary metrics: Incidence of Motion Sickness (MSI) and Effective Gravity Angle (EGA). MSI predicts percentage of people likely to suffer motion sickness (1‑hour exposure); EGA quantifies combined transversal and vertical acceleration effects (static + dynamic roll).
• Calculation basis: MSI and EGA are calculated in accordance with ISO 2631‑1:1997 (Annex D). The standard requires reporting the methodology used (empirical methods, computer programs or model tests).
• Sea states and spectra: Long‑crested irregular waves with a JONSWAP spectrum. Equivalent scatter diagrams combine western Mediterranean (GWS area 26) and Caribbean (GWS area 47) conditions (Hs 1–2 m specified ranges).
• Operational conditions: Two speeds assessed separately - 0 knots (stationary/DP/anchor) and 12 knots (transit). Standard uses a 135° heading (bow quartering) in a right‑handed coordinate system.
• Areas on board: Minimum five assessment locations: Owners cabin (OC), Dining area (DA), Wheel house (WH), Crew area (CA), Beach club (BC). Coordinates use geometric centers and a +1.2 m Z offset for deck height.
• Star rating and workability: Results map MSI/EGA outcomes to 0–5 stars; fulfilment criteria (EGA RMS < 2°, MSI < 10%) are measured as an up‑time/workability percentage weighted by peak period relevance (see Table B.2 and A.3 for weighting factors).
• Stabilization assessment: Calculations are run with and without an active stabilization system to quantify improvement. Passive external devices contributing damping are excluded from the “without” case per the standard.
• Exclusions: Jerk, roll damping derivation methods, stern-quartering seas, parametric roll risk, steering device influence, green water/wave impacts, yacht size compensation, gender/age dependency and habituation are explicitly not covered.

Practical applications

• Benchmarking and marketing: Brokers and owners can compare comfort levels across yachts using a standard 5‑star scale.
• Design and engineering: Naval architects and yacht designers use the methodology to evaluate hull/form/stabilizer effects on motions and to optimize interior placement.
• Stabilizer manufacturers: Quantify performance gains from active stabilization systems.
• Pre‑purchase surveys and owner decision‑making: Inform selection of vessels for intended use (cruising, charter, passenger comfort).

Who should use this standard

• Yacht designers, naval architects, shipyards
• Stabilization system manufacturers and integrators
• Yacht brokers, owners and managers
• Marine surveyors and technical consultants

Related standards

• ISO 2631‑1:1997 (Mechanical vibration - evaluation of human exposure to whole‑body vibration) - referenced for MSI/EGA calculation methods.

Keywords: ISO 22834:2022, large yachts, stabilization, sea keeping, MSI, EGA, motion sickness, JONSWAP, star rating, yacht comfort, ship motions.