Don, Searched the archives but couldn't find your post to reply to. Here are the deminsions on my cabin cushions. Port: I have two seat cushions the main seat is 73 inches long running from the bulkhead under the mast towards the quaterberth. ALL are 2 and 1/2 inch thick. This one is about 21 inches deep at the bulkhead and 26 inches aft. Fitting the curve of the hull. THe back cushions are divided into two, one is 34 and the other 33 long, twelve inches high and also 2 and 1/2 thick. I did not measure the seat cushion running from the aft end of the first into the quarterbirth as it was covered with gear. Starboard: The same. Attachment: There is a rib running horizontally along the hull. Attached to that is a piece of 1 by 4. To do this one you'll have to scribe the curve of the hull. once you do so that you have a curved edge and a flat edge with the flat edge facing into the cabin you lay the board on top of the rib and screw down into it. Then mine has 1/4 inch plywood screwed into that board with the plywood going about three inches above the board and rib. The plywood would be 73 inches long (it doesn't run into the quarterbirth)and 14 to 15 inches high depending on how deep you want the ledge behind the seat to be. The plywood and the seat back each have velcro attachments. The seat cushions just sit there. There is a 2 by strip of "teak" attached to the fron edge of the fiberglass bench which keeps the cushion from sliding into the cabin sole. If you'd like a photo semd me your email and I'll attach them to a rely. Later, Mike