New Requirements for Ship Speed/Power Trials from May 2026

Newbuilding Projects
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Hello QueSeanians,

From 1 May 2026, newbuilding speed trials relevant to the Energy Efficiency Design Index (EEDI) must follow the updated international standards for evaluating ship speed and power performance, namely ISO 15016:2025 or ITTC Recommended Procedure 7.5-04-01-01.1 “Preparation, Conduct and Analysis of Speed/Power Trials”, 2024.

From this date onward, ISO 15016:2015 will no longer be accepted as a reference for EEDI-related trials.

The updated ISO 15016:2025 retains the fundamental principles of previous speed trial analyses but introduces several methodological improvements aimed at increasing the accuracy, consistency, and comparability of results. The revision primarily focuses on refining the correction methods used to account for environmental influences during sea trials.

Speed trials are typically conducted under idealised reference conditions, such as calm water, no wind, and deep water. However, these conditions are rarely achieved in practice. Therefore, the measured speed and shaft power must be corrected for environmental effects before determining the vessel’s contractual or regulatory performance.

In practice, this means shipyards, design offices, owners, and verification bodies will need to update their procedures and documentation before the new rules come into effect.

Wind Corrections

The revised standard introduces updated wind-profile assumptions and maximum allowable wind speeds that depend on the ship’s length. In addition, two different wind-limit curves are defined depending on the type of wind measurement system used.

Advanced measurement technologies such as 3-D ultrasonic anemometers or lidar systems are encouraged because they provide more accurate wind measurements and allow higher wind-speed limits during trials.

The wind profile used in calculations has also been revised to better represent offshore wind conditions, improving the accuracy of wind-resistance corrections applied to measured speed data.

Modern sensor systems for wind and waves. Image Source: https://magazine.marin.nl/
Modern sensor systems for wind and waves. Image Source: https://magazine.marin.nl/941×556 99.9 KB

Wave Resistance Corrections

Wave effects represent another important source of uncertainty during speed trials.

The updated standard introduces a clear hierarchy for selecting wave-correction methods, depending on the availability of wave measurements:

  1. When detailed wave measurements are available, transfer functions from seakeeping model tests can be used to estimate the added resistance in waves.
  2. If such transfer functions are not available, the newly introduced SNNM method can be applied.
  3. When wave conditions are not directly measured and only visual observations are available, the simplified STAWAVE-1 method may be used.

To enable more accurate wave measurements, the standard also supports the use of wave buoys, shipborne wave radar, or drones to record wave spectra during trials.

Shallow Water Effects

he revised ISO standard also introduces an updated method for evaluating shallow water effects on ship resistance.

The older Lackenby method, developed in the 1960s, has been replaced by the Raven method, which was developed based on computational fluid dynamics (CFD) studies, model tests, and full-scale trial data.

The Raven method separately accounts for the influence of shallow water on viscous resistance and ship sinkage, resulting in a more realistic estimation of power demand in shallow or intermediate water depths.

Water Temperature and Data Processing

Additional refinements include updates to the correction applied for water temperature and hull roughness. The calculation process for speed and power relationships has also been simplified to improve consistency in data analysis.

What This Means for Speed Trial Results?

Although the changes mainly affect calculation methods rather than the trial procedures, they may influence the final results obtained during performance verification.

For new vessels or sister ships evaluated under the updated methodology, the difference is generally expected to remain relatively small but still important for regulatory verification.

Practical Considerations for Shipowners and Shipyards

The updated framework encourages the adoption of improved measurement technologies and better trial preparation.

Examples include:

  • Using additional wind sensors connected to onboard data systems
  • Deploying wave buoys to measure sea conditions accurately
  • Ensuring high-quality shaft power measurements
  • Carefully planning trials to avoid unsuitable environmental conditions

Accurate environmental measurements are essential because wind, waves, water density, and water depth all influence the calculated speed–power relationship during trials.

Preparing for the 2026 Implementation

For maritime stakeholders involved in vessel design, construction, and verification, preparation for the new standard should begin well before the implementation date.

Key steps include:

  • Updating internal procedures and contractual references
  • Reviewing speed-trial planning practices
  • Ensuring measurement equipment meets the updated requirements
  • Familiarising teams with the revised correction methodologies

As environmental regulations and efficiency standards continue to evolve, accurate and reliable performance verification will remain essential in demonstrating compliance and improving vessel design.

References

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