I was counting the time between waves recently and it matched up with the dominant swell period the buoys were showing (7-8 seconds). I'm curious what happens when you have two different swells hitting the beach at the same time with two significantly different periods.

Let's say you have swell #1 from the NE at 13 seconds and swell #2 from the SE at 7 seconds. Will some sets have waves spaced 13 seconds apart (those from swell #1) and other sets with waves spaced 7 seconds apart (those from swell #2)? I've never really counted to check but intuitively I don't think I've ever noticed this kind of difference in the wave spacing between different sets on any given day.