NavList:

A few comments.   

All the discussion by analogies is difficult, of course.   I haven't actually solved the Navier-Stokes equation and I imagine doing it in cases where funky things like gradients in current velocity are present would be fairly tricky.

Having said that - a few observations that I *think* are correct.

First on the Fisher's Island waves:   I've actually paddled in the Race off of Fisher's, it's quite a thrill.    In this case, the current itself will create a wind-stress.   If you have absolutely still wind, and some current flowing, the current itself will create waves due to the wind stress on the surface.    These will be "standing" waves - meaning that if you have a fixed reference in the distance, it will seem like the waves are not moving.     A few places where I've seen this include the southern tip of Monomoy Island (well, it used to be an island) off of Cape Cod, Woods Hole, and Sullivan Falls in Maine.

In terms of the iceberg analogy, I think he meant us to understand that a lot of action is happening beneath the surface - at least that was how I took it.

On the swells - now the issue of a gradient comes into play - it may very well be that the gradients are spread over a very long distance.  I thought about swells traveling thousands of miles and then encountering a current, and tried to figure this out - I would imagine that the period would be unchanged, but the wavelength would shorten or lengthen, depending on whether it was with or against the current. It might alter the shape, too.

On the focusing of waves - if plane waves encounter a velocity gradient, it will definitely be focused.   I believe that this is cited as being responsible for freak waves - e.g. the Argulas (sp?) current is notorious for this.

So, plenty of gradient generated effects - this may be what these folks are reporting in the quotations.