shen shows just how miserable is his understanding of tidal flows thusly:

okay squathead, you call 'em the way you see 'em and I will call them the
way
both the CG and Corps of Engineers see them.

but what do they know?


Exactly. What "DO" they know?
BTW, let's assume that the canal/lock in question runs N-S. Now, if the tidal
current is flowing at a good rate through the canal/lock from N-S, could we
assume that the water to the South is at a lower level than the water to the
North?
If you should answer this in the affirmative, then we can say that the lock
is
used to raise or lower (even if only inches) vessels, though the main reason
may have more to do with overcoming the dangers of a strong current, and get
vessels, safely through the area........ just a thought.

Shen