How to Upholster a Knee-Rise Seat Cushion With Curves

Item # X-HT-300644

If you own a speedboat whose upholstery has seen better days, then this is the DIY series for you! We’re overhauling the entire interior of a used Malibu speedboat. Be sure to catch all the entire Speedboat Makeover Series to see the entire transformation. In today’s tutorial, we will be reupholstering a knee-rise cushion. This cushion style features a knee-rise, curves, boxing that wraps all the way around the cushion, and a backer board that the vinyl upholstery is stapled to. Let’s get into it!

Learn how to make a vinyl boat cushion with curves.
This bottom seat knee-rise cushion with curves is part of our Speedboat Makeover Series.

We previously made a knee-rise cushion that is square in shape and has no curves (search #300464XHT for that tutorial). But we had a lot of requests from customers for a similar cushion style with curves and a backer board. We’re always on the lookout for tutorials that help our customers in their DIY work. So when the opportunity came to completely reupholster a speedboat with this exact cushion style, our DIY team jumped at the opportunity. We knew this was the exact DIY tutorial that our customers were asking for.

Knee-rise cushions have a fabric pull inside the cushion that separates the two different foams inside — the high-rise foam and the low-rise foam. This is what helps to create the firm front edge of the cushion, which is the distinguishing characteristic of knee-rise cushions. The original foam was compromised with some mold spots and had been flattened and compressed with time. We decided to replace the worn-out foam with new Sailrite® CushionRite™ foam. CushionRite™ is high-quality upholstery and seating foam suitable for all of your marine, outdoor and indoor cushion applications.

When it comes to vinyl boat upholstery, there are a lot of choices. Sailrite® stocks only the best, highest quality vinyl upholstery brands on the market. You won’t go wrong choosing from our selection of hundreds of vinyl upholstery fabrics. We chose EverSoft™ Indoor/Outdoor Vinyl Upholstery for our Speedboat Makeover Series. EverSoft is a four-way stretch vinyl. The fabric’s stretch properties make it easy to pull and staple the vinyl to a backer board, making it a great choice for this project. The textured pattern mimics the look of real leather for a high-end, luxurious style.

Speedboat upholstery DIY video series.
Here's a look at our completed project boat for our Speedboat Makeover Series. Be sure to watch all the how-to videos in this exciting DIY series.

In this tutorial video you’ll learn some valuable DIY techniques that you’ll be able to use on other projects as well. Some of the things you’ll learn include:

  • How to check foam for damage and evaluate if it can be reused.
  • How to use patterning material to trace the cushion shape and add transfer marks.
  • How to create and sew a fabric pull inside the cushion cover.
  • How to sew the two halves of the top plate together with the fabric pull.
  • And much more.

Are you ready to tackle this DIY boat cushion project? Press play on the video below to get started on this knee-rise cushion with curves tutorial.

Video Chapters:

  • Intro — 0:00 min.
  • Removing Old Fabric & Evaluating Foam — 3:49 min.
  • Patterning & Cutting New Foam — 9:18 min.
  • Creating & Sewing Fabric Pull — 13:09 min.
  • Cutting Boxing to Size — 15:23 min.
  • Sewing Two Halves Together — 19:00 min.
  • Trimming Top Plate — 22:11 min.
  • Sewing Boxing to Top Plate — 24:03 min.
  • Stapling Fabric Pull to Backer Board — 32:21 min.
  • Pulling Cover Over Foam & Stapling — 35:18 min.
  • Materials & Tools List — 47:04 min.

Materials List:

  • Dura-Skrim® Patterning Material 74" #103134
  • Super 88 Spray Adhesive 13 oz. #123287
  • CushionRite™ Standard Antimicrobial Foam (Medium) #124231
  • Fabric Backed Sew Foam 58" #124306
  • Headliner Adhesive 13 oz. #123288
  • EverSoft™ Indoor/Outdoor Teak 54" Vinyl Fabric #122218
  • EverSoft™ Indoor/Outdoor Black 54" Vinyl Fabric #122217
  • Top Notch® 9 Silver Gray 60" Fabric #120450
  • Polyester V-92 Thread from Sailrite
  • Seamstick 1/4" Basting Tape for Canvas & Upholstery (36 yds.) #122065
  • Polyester Carpet Binding Beige 1-1/4" #120236
  • EverSoft™ Vinyl Welting / Piping Black #122597
  • 21 Gauge 3/8" (10mm) Staples 10,000/Box (Stainless Steel) #8010SS
  • Cushion Wrap Silk Film 54" #103933

Tools List:

  • Staple Lifter #120037
  • Gingher® Scissors Right Hand Lightweight 8" #101017
  • Sailrite® Blade Foam Saw V2 with Carrying Case (110V) #121244
  • Scribe-All® Black Marking Pencil for Vinyl #121977
  • Tape Measure 120" #102986
  • Clear Acrylic Ruler 6" x 24" #102400
  • Deluxe 5-1/2" Magnetic Sewing Guide #103597
  • Sailrite® Deluxe Fabricator® Sewing Machine Package (110V) #400600
  • Cording Foot Set 1/4" for Fabricator® #400414
  • Left Edge Guide Foot Set 4mm for Sailrite® Fabricator® #400111
  • Sailrite® Short Nose Upholstery Staple Gun #121410
  • Marker, Pliers, Tape Measure