How to Make a Keystone Cushion With a Backer Board

Item # X-HT-300102

In many v-berths there is a cushion that can be added for extra sleeping space, or removed for standing room. This helpful cushion is referred to as the keystone cushion. The keystone cushion in the v-berth on our Powerboat Makeover was attached to a backer board. In this video, we’ll show you how we recovered that board to create a new keystone for our cushions.

Before & After V-berth Keystone Cushion

To make a keystone cushion with a backer board, you will sew together the top half of the cushion, which will then be fitted over the backer board and stapled in place. We patterned the shape and size of our keystone cushion on the boat when we patterned the rest of the v-berth cushions. You can see that process in our "How to Make Forward Berth Cabin Cushions" video (#300101XHT). Since our cushions use a patterned fabric, we made sure to line up the patterns when cutting the fabric for our keystone cushion for a cohesive look. Cindi carefully explains that process in the video.

With the keystone cushion being removable, we wanted the back of the board to be neat and nice-looking, for times it was removed and stowed. To do this we added a layer of Cushion Underlining fabric to the underside of the board and hid the raw edges of the decorative fabric with Hidem Gimp. This is an optional step, but one that does add a nice finished touch.

In this video you’ll learn how to pattern your fabric, sew on boxing and piping, cut the foam and staple the assembly to the backer board.

Video Chapters:

  • Patterning Plate – 0:39 min.
  • Making Boxing – 3:38 min.
  • Sewing Piping to Plate – 5:39 min.
  • Sewing Boxing to Plate – 7:22 min.
  • Cutting Foam – 13:16 min.
  • Attaching to Backer Board & Finishing – 14:50 min.
  • Materials List - 20:18 min.

Materials List:

  • Dura-Skrim® Patterning Material #122463
  • Marine Upholstery Fabric
  • V-69 Polyester Thread (we used Derby Navy #103795)
  • Medium 5/32" Welting Cord #107035
  • Seamstick 1/4" Basting Tape for Canvas #104167
  • Marine Interior Foam (we used 4" Dry Fast Foam #184M4872)
  • Cushion Underlining Fabric (we used Beige #103934)
  • Sailrite® 21 Gauge 1/2" (12mm) Staples 10,000/Box (Stainless) #8012SS
  • Seabrook 3/4" Hidem Gimp (we used Lite Glacier #120132)

Tools List:

  • Sailrite® Canvas Patterning Ruler #107040
  • Multiuse Pins #102985
  • Fabric Marking Pencil Yellow #111002
  • Gingher® Scissors Right Handed #19104
  • Clear Acrylic Ruler 6" x 24" #102400
  • Sailrite® Ultrafeed® LS-1 PLUS Walking Foot Sewing Machine #300502
  • Sailrite® Blade Foam Cutter #121244 or an electric kitchen knife
  • Sailrite® Long Nose Staple Gun #121411
  • Tape measure
  • Marker