As with a few posters here I have experienced the southern ocean swells. For me during a Westcoaster . We had a 40footer coming up behind our 35 footer for what seemed hours and when we were in the trough and the 40 footer on the crest behind it looked as if he was as high as our mast . At one stage I was wishing he would bear away as I was fearful of him landing on top of us

but he eventually passed with a couple of boat lengths between us.