Thwart

Don't snip yet. I don't know what kind of sanitation arrangements there may have been in former times on ships; I imagine there were none. So if you didn't have a nice flushing head like we have today, what did you do when you had a load to dump? My guess is that your bum went over the thwart. So, if "thwart" was pronounced in a New England accent, or some English accent and came out "twaht", is that a connection (connexion)? Hmmm.