Joe,

Disabled the machinery of a sailing vessel? Now that would be an interesting trick indeed...

You place too much faith in Lloyd's War Losses. I've spent seven years working through it. It's a very important work. It's also not 100% accurate. And it's also a secondary source.

In this case, U 46's KTB says "durch Signal angehalten" and does not indicate the sailing vessel was damaged. There's no listing of damage in the Danish lost list for 1916 or 1917. I don't see how U 46 can be credited with damaging LADAS unless there's something besides LWL to confirm that she was in fact, well, damaged.

And the case of U 57 and the trawler is clearly distinguishable, as U 57's KTB clearly states that the machinery was damaged but the vessel wasn't sunk.

Best wishes,
Michael