Jeff,

You're not telling the full truth with "Hell's Gate" are you? You are
leaving out the River flow. That is a constant and mentioned as a
variation to Tidal flow. There are many variations on Tidal flows,
including the Moon, which causes abnormal high and low tides. When
coupled to large bodies of water constricted thru small inlets the sine
wave will be knocked for a loop. Much like a clogged drain on a sink.
LIS has its share of them. The Narrows, Plum Gut, Fisher Island to name
a few. Every place in the World has its' variations, the higher the
Latitudes, the greater the number. Fundy, Solvent, Gibraltar, Georgia
Straits, Cape Horn, etc. The list is endless but local knowledge has
learned to handle it. That's why we sail. It is still more of an Art
than a Science!

Ole Thom