Writing The Rules
As wind assist projects proliferate Lloyd’s Register brings in new wind propulsion rules
Lloyd’s Register (LR) has updated its Rules and Regulations for the Classification of Ships by introducing new technical notations that formalise standards for wind propulsion systems.
The new rules come into effect on 1 January 2026 and introduce two new notations for wind-assisted propulsion systems, WAPS and WAPS* and the EASE notation for ergonomic access and human-centric design. The existing RIGGING notation definition is also modified.
The new WAPS and WAPS* notations have been established for systems such as wingsails, Flettner rotors, suction wings and kites and will be issued at owners’ request. They enable shipowners to classify retrofitted or hybrid installations, including those not originally classed by LR. By providing a structured framework for assessing the safety and integrity of these systems, WAPS and WAPS* support investment decisions and operational assurance across a wide range of vessel types.
Meanwhile, wind-assisted propulsion technology firm, Anemoi Marine Technologies and LR have published a paper to advance standardisation of wind propulsion performance methodology.
Anemoi says it has developed an in-service performance verification process that reduces cost and complexity for operators while improving accuracy compared to existing practices. The new methodology aims to enable greater uptake of the climate-neutral, energy-saving advantages of wind-assisted propulsion.
The methodology published in the new paper, Performance Verification Of Wind-Assisted Ship Propulsion Systems By On-Off Testing, can be used for all wind-assisted propulsion solutions, not just Anemoi’s Rotor Sails. Anemoi claims it overcomes the challenges of applying traditional methodologies, such as ISO 19030, to WAPS assessment and eliminates costly operational changes, such as taking vessels off-hire to perform dedicated WAPS sea trials, which are proposed by some standards. Lloyd’s Register Advisory confirmed that these benefits are accrued while improving the accuracy of overall fuel saving predictions.
The process involves measuring vessel data when the wind-assisted propulsion system is turned on and off while encountering various conditions during regular operation. The data is used to calibrate predictions on forces generated by the rotor sail system and their impact on the vessel, which can be used to predict voyage fuel savings with high levels of confidence.
In a similar but separate development, LR has validated wind assist company bound4blue’s “wind propulsion system force matrix” methodology for calculating Pwind in line with IMO guidance. bound4blue says the validation gives shipowners a “robust, credible and compliant means to calculate the Pwind value of installations, ensuring they unlock full regulatory (and cost) benefits under frameworks such as FuelEU Maritime, and EEDI/EEXI”.
The LR-validated approach utilises advanced CFD-based (Computational Fluid Dynamics) calculations, validated with wind tunnel test results. The installation earlier this year of four bound4blue eSAILs® onboard juice carrier Atlantic Orchard, chartered by Louis Dreyfus Company (LDC) and owned by Wisby Tankers, was the first to benefit from this methodology validation.
In another development, LR has awarded approval in principle (AiP) to HD Hyundai Heavy Industries (HHI) for a new very large gas carrier (VLGC) design that features a forward accommodation block and integration of wind assisted propulsion systems (WAPS).
By relocating the bridge and accommodation block to the bow, the vessel’s aerodynamic profile is dramatically improved, reducing headwind resistance and improving overall propulsion efficiency.
The fore-deckhouse configuration also provides clear, unobstructed space from midship to the stern, allowing for optimised sail spacing and placement of WAPS technologies. This flexibility also supports integration of other sustainable technologies such as onboard carbon capture systems (OCCS), alternative fuel modules for ammonia or hydrogen, and battery energy
11/12/25
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