Wikipedia eh? So if it's not there, it must be slang or "lack or nautical knowledge"?
It's the standard usage in racing
circles in this part of the world, and we do have a bit of "nautical knowledge" in the southern hemisphere, believe it or not.
First reference I looked at:
October 2012 eNews AUS News
- Tack on the knocks, sail on the shifts - upwind - lifted is the tack that, all things being equal, should take you closest to the mark.
- Gybe on the lifts, stay on the knocks - downwind - double-handed boats. Knock is the tack that, all things being equal, should take you closest to the mark.
- Don’t fall off too quick in a velocity knock - when the wind dies, the apparent wind will go forward and will feel like a knock, it is not, it is no wind. Some suggest aiming at the next mark till the boat speed and apparent wind speeds are compatible.