How to Sew a Knee-Rise Cushion With Fabric Backing

X-HT-300464

Many seats in powerboats and sailboats have a knee-rise cushion built into the seating. This type of seating helps hold the occupant into the seat when underway and it raises their legs slightly for a more comfortable seat. Typically, these cushions are used in luxury boats. In our video tutorial, we'll show you how to sew your own.

Video Chapters:

Selecting Foam - 1:17 min
Cutting Foam to Size - 2:37 min
Determining Plate & Boxing Sizes -5:54 min
Patterning & Cutting Fabric - 10:50 min
Installing Zipper on Fabric Pull - 16:30 min
Finishing Back Plate (Fabric Pull & Zipper Opening) - 18:46 min
Sewing High/Low Plates & Fabric Pull Together - 29:42 min
Preparing Boxing - 32:29 min
Sewing Boxing to Top Plates - 35:58 min
Adding a Top Stitch - 48:09 min
Sewing on Bottom Plate - 55:43 min
Inserting Foam - 1:03:37 min
Materials List - 1:15:33 min

Materials List:

CushionRite^® Premium Antimicrobial Foam (Firm) - (#124236)
Foam Lock Spray Adhesive 12 oz - (#120464)
Fabric from Sailrite^® – we used Sunbrella^® Horizon Capriccio - (#10200-0016)
Cushion Underlining Fabric from Sailrite - we used Phifertex^® Standard Vinyl Mesh - (#410123)
YKK^® Continuous Zipper #5 White (VISLON^® Chain) - (#28218)
Seamstick 1/4" Basting Tape for Canvas & Upholstery (36Yds) - (#122065)
Thread from Sailrite – we used Polyester Tex 90
YKK^® Zipper Slider #5 Single Non‑Locking Pull (VISLON^® Chain) - (#103178)

Tools List:

Clear Acrylic Ruler 6" x 24" - (#102400)
Sailrite^® Blade Foam Saw V2 with Carrying Case (110V) - (#121244)
Scribe‑All^® Black Marking Pencil for Vinyl - (#121977)
Gingher^® Scissors Right Hand Lightweight 8" - (#101017)
Sailrite^® Ultrafeed^® LSZ Walking Foot Sewing Machine - (#311602)
Ultrafeed^® Industrial Sewing Table - (#120934)
Thread Clipper Kuroha - (#121908)
Seam Ripper Deluxe - (#18104)
Deluxe 5 1/2" Magnetic Sewing Guide - (#103597)

There are a few things to consider before you begin this DIY project. First, if your existing knee-rise cushion has a backer board, then it is usually an outdoor cushion on a powerboat. If it’s in a cabin, then a backer board is seldom needed as it can damage the fiberglass that it rests on. A backer board can also make your knee-rise cushion bulky, heavy and hard to move around. This is actually very common for liveaboard boats because tables are lowered and made into full beds at night, so the cushions have to be moved all over.

If you want a knee-rise cushion but you don’t have boat seats with a backer board, then this is the video tutorial for you. The cushion that we'll be showing you how to create has a fabric bottom and a fabric pull with a zipper in it to separate the two heights of foam — the high-rise foam and the low-rise foam.

The knee riser in this tutorial is a straight cushion. We also have a video on a curved knee-rise cushion with a backer board. If that's the type of cushion on your boat, you'll want to search #300644XHT on our website for that video tutorial.

We're going to be making this cushion out of a high-performance engineered synthetic leather that's safe for outdoor use. Our selection of indoor/outdoor vinyl fabrics have what it takes to stand up to the rigors of your boat. They are completely waterproof and boast a fantastic resistance to abrasion, stains, fading, mold, mildew and more. And with our incredible selection of colors and textures, you're sure to find a vinyl fabric that works for you. You can also use woven fabric for this project and the directions are the same.

You can use this type of cushion for your interior or exterior marine seating. Many of our performance vinyl fabrics can be used indoors and out. But just to be safe, you’ll want to make sure to pay attention to the recommended uses section when choosing fabric for this project.

How did your cushion turn out? We'd love to see your finished photos in the comments section below and hear your thoughts on this video tutorial. Thanks for watching!