In the case I experienced, the tide was slack, there was little to no wind and the ship was not negotiating a turn. I also didn't think the ship was moving particularly fast. I would say that I remember scanning the wake from the stern of the ship to quite a distance behind the ship and the waves seemed to gain energy long after the ship had passed. I remember wondering if this ship might have had a particularly large prop that had imparted some unusual energy into the wake.
You know, I just happened to realize that after the wave incident, I paddled around a bit and then headed for an island that earlier had several fishing boats anchored off. I noticed that all but one boat were gone. I didn't think much about it, but I went to shore to check out some flotsam. I picked up two lifevests and a rubber fender and after a bit of a break, I headed back out in the direction of the one remining boat. The people in the boat were friendly, so we talked for awhile.
One of the reasons I went to the boat was to see if they had experienced the ship wake. They said that they hadn't seen any ships, but they had actually just gotten there a little while before I came along. Now I'm wondering if one of those boats that had been anchored near that island might have had some kind of upset. There have been no reports of a sinking that I know of.