mmmmmmmm the English language is a tricky & complicated
.....thing .....& I am sure the nautical definitions provided are totally correct...however
The literal term of....."auxiliary" .......refers to ..."backup" or "support" ...therefore it could be contested that the term "auxiliary ketch" is simply a "back up" or "support vessel"
Following on from this after referring to my trusty
"butterworth" guide......such comments of a ketch being sail.......
or sail with or without an auxiliary engine
are questionably meaningless
The ketch itself is the auxiliary element
...............Derek
PS1....the co-author [GT] is a relo & a professor of English language @ Flinders university in Adelaide in the land of OZ
PS2....I have just spoken with [GT]...& he concurs with my view..........