These are the the plans I drew to make removeable doors for my 1985 Catalina 30. Two strips fill in the slot of the opening and are attached by screws through the hinges. The other part of the half hinges are let into the sides of the doors. The top rail is actually two 0.25" pieces, and the stiles and bottom rail have a 0.25" grove on the inside for removeable panels to slide in and out. (0.1875" works best for the panels.)
The stiles and rails are attached via mortise and tendon joints, but you could get by with half-laps. My first attempt was with white oak, but they warped badly after a few years in the Atlanta area sun. Second attempt was Cumaru (Brazilian Teak) but it is checking after 5 years in the weather. Teak or Ipe may be a better choice. The wood is 0.75" thick, except the bottom rail which was a full inch so I could carve the dolphins. Remember wood width and thickness is actually smaller than what the label says, 1x4 is actually 0.75"x3.5".
Under each removeable panel you need to drill a few (at least 3) weep holes at an angle so rain water can drain otherwise it will fill the groove in the bottom rail and spill into the interior.
On my new 1995 Catalina 36, I used PVC lumber glued up into sheets to make my prototype doors. For these I routed a ledge along the opening and glued the acrylic panels permanently into place. (In this version the top rail is one solid piece, not two.) This keeps them from getting scratched inserting/removing/storing them and removes the need for the weep holes. Removeable privacy panels were made to insert into the openings from the inside.