I've been mulling for a couple years how to get the guest cabin to cool/heat better when guests have both cabin doors closed (43 has a door to the head and a door to the galley). Finally got around to doing something and it works well. I had considered a vent through the door but never liked how it would look. I also considered venting the cabin into the return for the salon that runs above it but never felt comfortable with my skills at installing a vent through the cabin vinyl ceiling. Instead I cut an opening throug the wall and installed a couple of wood vent panels (actually made for 4x10 floor HVAC ducts) on each side. Finished it up today and tested in the 90 degree heat (100+ heat index). Closed both cabin doors and let the GenSet and AC run for about 20 minutes and when went inside it was as cool as the rest of the boat. Looks pretty much like it was made that way.
Nice work.. I replaced all the ducting in mine and bumped up the size of the registers too. Every bit helps