This is one of the easiest & least expensive of boat projects in the last 1 1/2 years of remodeling work on 1979 382, which makes a big visual difference.
We used closed cell insulation from Home Depot for insulation next to cabin top (really can feel the difference with AC). Fitted 3/4 inch insulation pieces next to existing wood supports for liner ceiling trim.
Used contact cement (spray easiest) to glue new liner material (West Marine beige liner material) to 1/4 inch marine plywood. The only piece which had to be cut to get out of hatchway, was entry way by gallery, two pieces now. When liner was down, we cut opening for new bowmar hatch for gallery (12 X12), which gets air down into pervious HOT gallery area.
We then used the same beige liner material to replace hull liner in quarterberth. Used wood paneling in v-berth (i.e. 384). Again a easy project. The liner & ceiling replacments also made a difference in "boat smell", as all new now.
Would suggest taking pieces home to use table saw for cutting new plywood & used dining room table to get no-winkles in new liner, while gluing material. Put back up with existing wood trim pieces for ceiling.
We have learned more about which "boat pieces" were first, after hull, replacing the liner, ports, hatches, upper wood paneling by portlights, etc. Each piece of plywood & liner has the boat make 382 & with hull number. Amazing interior construction, by hand, piece by piece.