In this paper the response of two innovative floater concepts couplet to the IEA 15MW reference rotor to different wind and sea states is presented. The floater concepts are interesting and innovative, and could potentially bring cost reductions to the FOWT industry. The methods used are credible and in line with the current state of the art. However I think the paper can be improved. The research objectives should be stated more clearly, as well as the expected impact of this work. Moreover results should be discussed in a more critical way.

The paper is generally acceptable as-is with minor typographical errors to be corrected. 

Data presentation could be slightly improved by including more information in plots.

The approach taken appears to be generally acceptable and results are well explained.

It would be advantageous to have more information with regards to the specific tuning of the 

controllers and perhaps open access to the controllers for purposes of repeatability.

This paper introduces two floating wind designs to be used within the CoreWind project.  I only have minor comments, which are provided within the attached text.