On some cargo ships there are little holes in the deck with hooks inbedded. You take a 3-4" wide strap and secure one end into the hook, throw the strap (ususally about 20' long) over the cargo contanier then hook it to the other side and tighten it. Not unlike a belt. You can do it in various ways, but I dunno if this is done on these ferries.
Anyway, it definitely must've been an experience for the passengers. I researched and found that the ferry (the name escapes me) linped into port with a serious list. I'm sure the crew had alot of...um...you know what... to clean up afterwards. I'm sure alot of meals eaten beforehand came out. The wrong way. If I was on that ship I'd of had my life vest on and my eye on the nearest escape passage.