Scott,
I watch a show on TLC a few years back. Couple of scientists were doing
some research on waves in general. I remember they set up a demo that
showed that small waves can synchronize and in effect become the occassional
bigger wave. Perhaps you are seeing this?
Scout

"Scott Vernon" wrote
Every now and then, a group of 3 or 4 big waves (4'?)would roll by.
I've noticed this for some time, they always seem to be
in a group of 3 or 4. Not power boat wakes.