Things You'll Need
Heavy-duty sewing machine
Heavy-duty sewing machine needles
Heavy-duty nylon thread
Walking, Teflon or quilter's foot
Marine vinyl stands up to harsh sunlight and even harsher saltwater, making it the ideal material for boat cushions. You can purchase marine vinyl from most fabric stores or marine specialty stores. The vinyl has a shiny surface and a knitted fabric back and comes in many colors. The material is quite thick and slippery and requires special sewing techniques. If you want to make new cushions from marine vinyl or repair existing cushions, you'll need special equipment.
Place a piece of tissue paper underneath the vinyl before you begin to sew. The tissue gives the sewing machine's feed dogs something to grab onto and will help move the vinyl through the machine evenly.
Set the stitch length to between two and three stitches per inch. This will keep the thicker fabric from bunching.
Thread the bobbin and top needle with heavy-duty nylon thread. This thread is sturdier than cotton and will be less prone to break as you sew.
Sew with a walking, Teflon or quilter's foot. These special feet feed tough fabrics like vinyl through the feed dogs together.
Sew slowly and use one hand to gently pull the layers of vinyl under the needle and out the other side. Don't pull too hard or try to go too fast. Aim to work slowly but at an even pace.
Backstitch your seams to keep them from coming apart.
Use a heavy-duty sewing machine, preferably one designed for sewing upholstery or leather. A lightweight machine could overheat or burn out under the strain of sewing through several layers of vinyl.
Use a heavy-duty needle, one designed for upholstery fabric.
If the fabric is still getting bunched up, try tightening the tension on the machine and using a piece of tissue paper under the fabric.
With heavy upholstery fabrics, the longer you make your stitch, the easier it should be to sew.