How to Construct Boat Cushions

Cut out shapes in the foam sheet to fit your boat deck or interior spaces. Your foam should be as thick as you want your cushions, but should be at least 2 inches thick to provide some padding. For very thick foam or certain types of foam you may need utility scissors, but thin foam is easy to cut with standard scissors.

Cut the shapes to exactly fit the spaces you intend to cover. Measure the spaces or make a paper template, if necessary. Depending on your storage situation in the boat, you may also want to cut large pieces of foam into interlocking sections that will be easier to store when not in use.

Select a plastic foam variety that is somewhat resistant to water and will not absorb too much moisture or grow mold. Boating supply stores sell several varieties of foam; you should also be able to find good foam at home improvement stores if you keep the proper specifications in mind.

Cut two pieces of fabric to the same dimensions as your foam piece, leaving a half inch around the entire measurement for stitching.

Stitch three sides of your cloth. Fold the cloth ends in about 1/4 inch inch to avoid fraying and run the stitch over the overlap in the two pieces to join the two. You can complete this step with a sewing machine if you have one or manually with needle and thread.

If you are having trouble folding over your cloth, sew the pieces together with a stitch about 1/4 inch from the end and then turn your sheets inside-out.

Hem the remaining side by folding each cloth over by 1/4 inch and stitching across the hem. Do not connect these two ends of cloth. You are simply creating a border to avoid fraying at the cut edge and will be attaching buttons to this end.

Attach a button every four inches starting at the beginning of the opening and running the full length of the side. Attach as many buttons as you need to cover the length, but make sure you are applying at least four, one on the top and bottom and two in the middle. Stitch the button to the cloth near the end, running thread through the loops or holes. While zippers can be easier than buttons, salt water and sea air can rapidly corrode zippers, making buttons a better choice for boat furniture.

Cut slips in the opposite cloth to fasten the buttons. Make small cuts with your scissors that are about the width of each button or even slightly less. Stitch the ends of the cut to avoid fraying and tighten the cloth's hold around the button.

Insert your piece of foam and button the open side to close the slip.