It would be one of the few times,,, I am posting my STCW certificate so you can take a look,, maybe I read the certificate wrong but it does say MASTER,, but also says aux. sail so maybe I am wrong.
Capt A you are 100 percent right again,,, a little internet digging brought this up
An "endorsement" is a provision added to
a license that alters its scope or application. A license to
operate motor vessels must be specifically "endorsed" to
permit service aboard sailing vessels or auxiliary sailing
vessels. The difference between a sailing vessel and an
auxiliary sailing vessel is that the latter has an auxiliary
means of propulsion (i.e., an engine).
Refer to the individual license requirements under "Sea
Service Requirements Regulations" for license en-
dorsements for service on vessels of 200 gross tons or less;
but for licenses greater than 200 gross tons refer to 46
Now I wish I had not told them about the 15hp on the back of the sailboat,,, not that it was any use but in the icw