The manuscript presents wind tunnel experiments on a dynamically yawing scaled wind turbine platform, designed to emulate the motion of a floating offshore turbine subjected to helix-type control inputs. The authors show that wake recovery is enhanced when the helix actuation is in phase with the yaw motion, and they provide an explanation based on vortex interaction mechanisms.

Overall, the paper is clearly written, the figures are of high quality, and the topic is timely and relevant to ongoing research in floating wind turbines and wake control. The results are novel and potentially valuable. However, before publication, several aspects—particularly regarding the physical modeling, scaling assumptions, and the description of the QBlade simulations—need clarification or expansion.

Below, I provide major points of discussion followed by specific comments where I refer to the lines of text in the preprint pdf.

I hope they can be useful to improve this work, and I look forward to see a new iteration.

Major Comments

1. Description of the QBlade Simulations and Motion Scaling
   
   The paper’s methodology relies heavily on simulated platform motions obtained with QBlade, which are then prescribed to the moving platform in the wind tunnel. Currently, this description is in the Appendix and lacks clarity. I strongly suggest moving this material into the main text and expanding it. In particular: the simulations use multi-megawatt rotors and realistic floating platforms. How are these motions scaled to the MoWiTo model? Please discuss the scaling laws (Reynolds, Froude) and justify whether dynamic similarity is preserved.
   
   It appears that only yaw motion is modeled, while wave-induced and tilt motions are neglected. Please clarify whether this simplification is justified, and discuss its implications for the generality of the results.
2. Impact of the low tip speed ratio
   
   The scaled turbine operates at an optimal TSR of 5, which is substantially lower than that of modern large turbines (typically 7–9). The paper should discuss how this affects the wake development and vortex dynamics.
   
   In Fig. 7, the near-wake differences between in-phase and anti-phase cases are significant; however, with a higher TSR the near wake would likely contract and recover differently.
   
   Similarly, the characterization of tip and root vortices (Fig. 8) should note that vortex strength and persistence depend on TSR.
3. Possible Complementary CFD Analysis
   
   The results could be strengthened by comparison with or validation against CFD simulations (e.g., LES ALM). Even a qualitative comparison would enhance the credibility of the wake structure analysis.

More specific comments:

• Title: From the title, it is not clear that the helix is being applied or that dynamic yaw is being investigated.
• Introduction: a discussion on the state-of-the-art research for dynamic yaw is missing. In fact, dynamic yaw has also been studied as a mixing technique. As such, it features its optimal actuation frequency and amplitude. It would be interesting to include an assessment of this with regard to your experiments.
• Line 18: Why can a wind farm experience an efficiency drop? I guess it is because of the wake effects. Please clarify in the text.
• Line 19: sentence could be a bit more formal/technical
• Line 23: There are articles around where wake steering through floating platform motion was investigated, but from this sentence, it seems like something like this has never been done.
• Figure 1: Please add in the caption what is being shown (i.e., Q-criterion), and how this was obtained (i.e., LES ALM, CFD, ...)
• Line 45: f_e is introduced as the actuation frequency. With the Helix method, however, there is an ambiguity because the actuation frequency of the pitch motors is different from the rotation frequency of the thrust vector. Please clarify what f_e is.
• Figure 2: What turbine was used in these simulations? What ambient conditions? Is this a scaled result? Perhaps the x-axis could be normalized?
• Line 52: As I mentioned earlier, the dynamics of the floating platform must be well modeled, since it is the foundation of your work. I would move the appendix section to a dedicated, expanded section where Figure 2 could be inserted.
• Line 59: The energy amount needed to actuate the blades with the helix is important. Can you quantify how much energy is "some energy", as a fraction of rated power, for instance?
• Line 60: can you provide a number for how much the power generation is increased?
• Line 67: "The wind tunnel experiments are carried out that combine a hardware...": this sentence is not clear.
• Line 70: the yaw motion is prescribed, but what about the effects of waves, other DOF other than yaw, and other higher frequency motion? Please discuss why they were omitted, and the limitations associated.
• Line 94: Please report the blockage ratio: Is blockage biasing your experiments in any way? Especially if the rotor is placed in proximity to the jet outlet, I expect that there could be some blockage.
• Line 96: Are 2 kHz enough to capture the floating platform dynamics, considering time scaling?
• Line 107: discuss the implications of a rather low tip speed ratio.
• Section 2.4: How was the helix amplitude chosen?
• Section 2.4: The phase offset between yaw and helix is not defined very clearly to me. Perhaps you could add some equations that clarify what $\Delta Phi$ is.
• Line 166: could this be explained by a study of the instantaneous deflection of the thrust vector due to yaw and due to the helix?
• Figure 5: it would be nice to see errorbars here.
• Figure 7 and 8 and relative analysis: I wonder how these results would change with a higher operational tip speed ratio.
• Line 177: How is the instantaneous energy advection defined? Please add a formula.
• Line 180: The reason why the lower part of the wake is neglected is understood. However, there is no discussion on how big is the sector that is left out (aperture angle), and why it was made this way. This is not a good practice, since it seems an arbitrary choice. Perhaps by comparing with older measurements, the impact of the hexapod could actually be quantified and accounted for. Or LES simulations could be used to clarify this point.
• Line 190: How general are these results if the effectiveness of the in-phase actuation is limited to the near wake?
• Line 200: How was the tip vortex tracked in Figure 8b? The procedure for the root vortex is specified, but not the one for the tip vortex.
• Line 205: "encroachment" is a bit difficult word. Consider replacing with a more common synonym.
• Appendix: 
  
      - line 232: "a simulation suite capable of simulating", remove repetition 
  
      - line 234: what are OC4, TripleSpar, and VoltrunUS-S?
  
      - line 261: Why is the future tense used here and later?
  
      - lines 264, 265: lack of citations for "... these motions are significantly smaller than those excited by the Helix method itself.", and "the frequency of wave excitation is typically an order of magnitude higher than the application frequency of the Helix". These are rather important statements that require a citation or a discussion, in my opinion.
• Side note: if the MoWiTo is equipped for it, it would be useful to quantify the fatigue and actuator duty cycles for the different scenarios investigated.

The paper presents a wind tunnel experiment investigating how the yaw motion of the floater of a floating offshore wind turbine affects wake recovery when combined (or not combined) with HELIX wake control.

The paper is well written, and the study is highly relevant to the wind energy community, as it addresses the important topic of wind turbine wake control.

Therefore in the reviewer’s opinion it deserves publication to WES after the following listed points are addressed.

1) An important consideration in wind-tunnel wake measurements is the influence of ambient turbulence. In the present experiment, the ambient turbulence level is relatively low (0.5%–2%), considerably lower than what is typically observed in the field. As a result, although the qualitative trends remain consistent, the quantitative conclusions may differ under real conditions, where higher ambient turbulence enhances and accelerates wake mixing. It is recommended to the authors to address this point in the introduction and perhaps in the conclusion section and discuss the limitations. Please indicate the lessons learned by the experiments you cite in the introduction section with regard to the above point.

2) Figure 2, which presents the frequency-response analysis of the realistic dynamic system of a floating offshore turbine, indicates that the phase difference between the pitch motion and the platform’s yaw motion is closer to 180 deg than to 0 deg. In contrast, the experimental results suggest that mixing is enhanced when the two motions are in phase. The frequency plots in Figure 2 represent the response of a dynamic system that cannot be subject (at least not easily) to modulation. Therefore, while it is interesting that in-phase motion appears to enhance mixing, it may be unrealistic to assume that such perfectly in-phase motion can occur in practice. Please comment on this issue.

3) A detailed wake measurement campaign was carried out, and it is unfortunate that the paper presents only the averaged cross-sectional wake velocities. It would be helpful if the authors included a plot showing the spatial variation of velocity within the wake, illustrating how the enhanced recovery observed in certain cases is distributed across the wake region. Such data could serve as benchmark results for validating numerical models. The pattern plots of figure 4 do not provide that necessary quantitative detail.

4) Please provide the formulas used to calculate the energy advection, along with details on how this quantity is computed.

5) For the sake of completeness and clarity, please indicate whether the picture in Fugure 1 is a schematic representation of the wake or a result of simulations and of what kind of simulations.

6) Please rephase the following sentence which is unclear (in Section 2, second sentence)

“The wind tunnel experiments are carried out that combine a hardware-in-the-loop setup and tomographic particle image velocimetry (PIV) to represent and measure the turbine dynamics, the coupled hydrodynamics, and the resulting aerodynamics.”