In your guide (https://www.tekhelet.net/guide.htm) it says "The Yemenites have a tradition (even with white tsitsit) of tying a special knot that is the chulya" - in the diagram that is given there, it looks to me to be the same as what you have in your video for the Rambam tying the middle chuliot (https://www.tekhelet.net/diagrams/video/Rambam2.MPG). So I am trying to understand if the Yemenite chuliot are different from the Rambam or not.
The Rambam describes his method in his Mishnah Torah (Hilchot Tzitzit 1:7-8), wherein there is room for interpretation, and that is what the Yeminites have done – preserved an interpretation of the Rambam’s method. In Hil. Tzitzit 1:9 the Rambam explains that his custom is to tie according the method described for tekhelet even when no tekhelet is available – and the Yemenites have indeed followed this custom throughout the ages. Thus, we are of the opinion that they have preserved the authentic interpretation of the Rambam’s method.
Regarding the video illustrations of the Rambam’s method according to the Yemenites: Videos 1 and 3 shows how to tie the first and last chulyot (respectively), both of which incorporate a white wrap with two blue wraps. Being that the Yemenites were only tying with white all these years that tekhelet wasn’t available, they were unable to preserve a tradition for these “special case” chulyot. As such, one of the people who used to tie tzitzit for Ptil Tekhelet, Noam Kaplan, developed a method for these chulyot (shown in Video Clips 1 & 3). Video 2, which shows the method of tying a complete blue chulya, is the method transmitted by the Yemenites for tying a complete white chulya.
– Mois Navon.