Like this or thicker . https://www.homedepot.com/p/Everbilt-3-32-in-x-200-ft-Stainless-Steel-Uncoated-Wire-Rope-810060/204471269
Here are the brass pulleys. The U shaped clips were screwed into solid thick wood under the gunnel cap with 1-1/4’’ wood screws .
The hull of my boat is probably 3/8’ cold molded veneer plywood . I hate the thought of a through bolt through the side of that but definitely want to be safe .