Removing the Old Boat Upholstery
- Remove the old boat upholstery from the seat cushion by removing staples being careful not to damage the foam if it will be reused. Some boat cushions may have additional staples between the marine foam and marine plywood.
- Once the fabric is removed from the foam and plywood you should mark or number the fabric with chalk. This will serve as a sewing guide so you know at what points the new pieces should be sewn together.
- Remove stitching from the old fabric with a seam ripper tool or single edge razor blade. The old vinyl will be used as a pattern for the new boat upholstery.
Inspecting the Existing Foam and Board
- After removing the boat upholstery per the instructions above, determine if you can reuse your existing marine foam and marine plywood. If the existing foam and plywood are in good condition you can re-use them if you want to.
- If the existing foam is sagging or water damaged it will need to be replaced.
- The plywood will need to be replaced if it has water damage or if the laminate has warped or come off.
Replacing the foam
Over time foam loses some of its mass and has likely shrunk. If you are reusing your old foam it should already have settled into its shape, but should not look collapsed or damaged in any way.
If it needs replacing:
If you are purchasing new foam, the marine foam should be 3/8″ larger than your marine plywood on every side and between 3” and 5” thick depending on the type of boat.
Pontoon boat upholstery is generally the easiest to replace and will use 5” thick foam whereas others may use as little as 3”.
Marine plywood should not be warped in any way and the protective laminate should be in tact. If you see peeling or warping it should be replaced or you run the risk of getting water damage to the boat upholstery.
If it needs replacing:
The marine plywood should match the existing plywood.
You can use the existing material as a template for the new material.
Making the Patterns
- Lay out your new boat upholstery vinyl with the marked pattern pieces over it and arrange them on the new vinyl in a way that will help you utilize as much new vinyl as possible. Try several layouts before cutting to make the most efficient use of the new marine vinyl.
- Once you have figured out where the pattern pieces will be cut place weighted objects on the pattern pieces to help keep the pattern vinyl flat and in place while you trace it using chalk. It will be helpful to transfer the sewing guides from the pattern pieces as well.
- After the patterns are marked cut out the patterns.
Note: We highly recommend that you use an industrial sewing machine for this project in order to avoid damage to your household machine. Use household sewing machines with care and at your own risk.
Make sure your sewing machine is capable of handling upholstery material. Boat upholstery vinyl is very heavy material so you will also need very heavy industrial grade bonded polyester thread to hold the pieces together properly.
You can use two tone colors or accent colors within each pattern as long as the overall pattern of the seat stays intact. Keep this principal in mind if you are making a custom seat cushion with multiple colors.
Securing the New Boat Upholstery
- After your boat seat cover is sewn, lay it over the foam and plywood base you will be using. Once you have the material in the correct position you can start securing it using a staple gun.
- The boat upholstery will be secured to the plywood bottom on the cushion underside starting with corners taking care to tighten any slack.
- If there is any material between the thin foam cushion and the front foam bolster (pull strip), tack this in place.
- Once all four corners of the seat have been secured, finish stapling with a staple every 1″ across each side. Trim any excess vinyl to within 1/4″ of the staples.
- Use cushion underlining to cover the exposed underside wood and trimmed vinyl edge. Staple the cushion underlining into place, with staples every 1”. Trim any excess getting as close to the staples as possible but no less than 1/8”.
- Finish off the underside cushion underlining with matching Hidem welt trim. Hidem is designed to hide upholstery staples and to give the seat a finished look. Lay your Hidem welt trim 1/8″ inside the wood edge. Center your staples between the two vinyl flaps on the Hidem and place a staple every 1.” Continue around the bottom edge of your boat cushion until complete.