NavList:

Joe Schultz, you wrote:
"you can think of a wave as a rolling iceberg. The wave rolls and rolls as it travels and, just like an iceberg, at least half of the wave is underwater."

Hmmm. While I don't agree with George's assessment, this comparison doesn't seem to help much. Waves have a rolling component, yes. Waves have "deep roots" compared to the visible size on the surface. That's like an iceberg. Anything else? Am I missing something?

And you added:
"Currents have depth, too, and currents will change the wave's rolling motion. At some point something has to give - the current isn't going give up so the wave has to change it's ways. That's the simple answer."

Well, yeah, but that 'simple answer' is not really an answer at all. What we're trying to figure out here is how it actually works. A proper theoretical model, even if it's very simple, can help us figure out the circumstances under which one can get useful navigational information from the appearance of waves in a current.

And:
"Currents can also change the nature of swells. They're just waves of a different nature."

Yes, very long wavelength but otherwise, no fundamental difference.

And:
"Temperature, color, salinity and critters are also indicators."

Quite so! And for observers who have time to kill (not usually those busy running the boat) apparently these can be very obvious indicators. Ben Franklin's notes about crossing the Gulf Stream from way back in the 18th century mention all of these things. The flora and fauna can change significantly. Along southern New England, it's often possible to tell when a Gulf Stream eddy has travelled north by the presence of large quantities of Sargassum on the beaches. Those often include exotic invertebrates and occasionally small fish not normally seen outside the tropics.

-FER