I’ve received an enquiry from Vaiko C-6 who has been producing hulls for decades with headrest as shown on the drawing asking to confirm that this design fulfills A.13.
Vaiko is confused with various opinions presented in this topic, however his interpretation of A.13 is that top crown has to be 2” radius minimum. Area outside is not limited by the rule.
I agree with Vaiko. In his drawing corners are rounded to 10mm radius but this is just individual preference.
Drawing here: http://serwer1376810.home.pl/P55_Images/img_1665.jpg