My '75 has 4" cushion depth. Go to sailrite.com and search cushions. They have very good video's explaining that very topic and other stuff as well. I just fabricated a companionway cover and a Bimini using that site for supplies and how to info. I'm getting ready to reupholster the entire boat. I will do the salon area for under $300 using Sunbrella interior marine fabric, reusing the cushions.