I have seen that type of cushion construction, but we do not have it.
For our bunk cushions, all of them have a 6mm closed cell foam pad under the "sleeping foam". This has eliminated mildew under the cushions.
For the saloon
, we have leather (which has held up quite well) covers over the foam, and the underneath is breathable cloth, and no mildew there either.
Why this is of interest to you is that the previous owners took the boat to Alaska
by way of Japan
, having left from Queensland
. For their second season in Canada, they added a Fab-All heater, and insulated underneath the deck
in the head
and forward cabin
. They did not insulate elsewhere, nor install forced air heating
I have a personal prejudice against piping, in spite of the crisp appearance it can lend, because it takes chafe and wears obviously before the rest of the fabric. It is important to use only plastic zips, or velcro can be used.
There's another way of approaching the situation, shown me by a Canadian cruiser about 18 yrs. ago. She liked to buy inexpensive cotton fabric, and make her own saloon
cushion covers about every three years. She enjoyed the projects, and the changing environment
, plus the cushions were mementos of places visited. Some people bought serapes in Mexico
, and used them for that, as well. Generally speaking, cushions are fairly simple shapes, and cushion covers easy to make, mostly all straight seams.
Have fun with your project
. If you go all vinyl, you'll need something over the covers both when it's very hot, and when it's very cold.