This little brass plaque has been on our bookshelves since my oldest son, one of the boat owners and the main maintenance guy, was a child.  I guess it didn’t cause him much concern because this is his second adventure into boat responsibilities.  The new boat is a 1974 Albin 25 that has not had much in the way of TLC for the last 20 years of its life, but it’s a good safe vessel for my son and his family to use for holidays and trips to their family cabin at a boat access only beach. Since diesel mechanic isn’t in my particular skill set, the only real help I can provide is to sew stuff.  I offered to help replace anything covered in fabric and this is my first attempt at seat cushions for a boat.  I’m sure I’ll get to do more of them. There are still two sleeping areas that require attention!

foam form-resized

We started with 3 inch high density upholstery foam that makes a nice solid seat that doesn’t “bottom out”. The foam is covered with a 3/8″ polyester fibrefill quilt batting, which is then covered by an under-cover.  For the under-cover, I used athletic mesh knit like this one.  The final step is the decorative cushion cover.  In this case we didn’t want vinyl so we chose a medium weight, light blue outdoor fabric by Sunbrella ordered online from JT’s Outdoor Fabrics .   This particular cushion needed to be a weird shape, but foam is easy to cut with an electric carving knife (available on Amazon for about $20).

pattern 1-resized

Once the foam was cut to the size we needed, I made the pattern for the under cover.  Medical exam table paper is perfect for quick disposable (or not) patterns.

pattern 3-resized

Place the paper over the foam and pinch the edges to make a fold line.  It will be somewhat uneven but a straightedge and french curve are all you need to straighten out the pattern.

pattern 5-resized

I try to keep the stitching lines just inside the edges of the foam so the fit would be quite tight. The under cover serves a purely utilitarian purpose. It holds the batting in place and makes it easier to remove the decorative cover for cleaning without tearing the batting.

pattern 8-resized

After the pattern is drafted, add a 1/2″ seam allowance, cut out the pattern and check the fit one more time.  For the edges, I cut a strip 3 7/8″ wide and long enough to go around the perimeter of the fabric with a couple of inches of overlap.


Once the pattern is made I covered the foam  with a 3/8 ” polyester fibrefill quilt batting, using spray adhesive like this one to hold it in place.  The batting is easy to cut with scissors.  Every sofa, chair or other upholstered thing I have seen has had the foam component covered in fibrefill so I just did that here without really thinking about why.  I believe it makes the surfaces smoother and generally softens the corners and contours.

Underlining 1-resized

finished under-cover-resized

After covering the foam with the quilt batting, sew and install the the under-cover.  The under-cover is definitely necessary if the decorative cover is ever going to be removed for cleaning. I think the athletic mesh fabric serves this purpose beautifully.  It’s cheap, stable with equal crosswise and lengthwise stretch, and almost indestructible.  I got the fabric at Dressew for $4 per meter, but it is widely available and never seems to cost much. With a 1/2 inch seam allowance, the edge will  finish at 2 7/8″ and will stretch to fit snugly over the batt covered cushion.  I closed the opening with hand sewn stitches, since this cover will not need to be removed.

Finishing the cushions2-resized Finishing the cushions3-resized


The first step in making the decorative cover is to make a new pattern based on the cushion form with the undercover in place.  I followed the same steps as when making the first pattern based on the foam.  I felt a new pattern would be more accurate and it doesn’t take much time.  For the edge strip which connects the top and bottom, cut a 3 7/8″ straight strip a couple of inches longer than is required to go around the perimeter of the cushion top and bottom leaving an opening across the back for the zipper strip.  When attached to the top and bottom with a 1/2 inch seam there will be 2 7/8″ between the seams.  That will be reduced to about 2 3/4″ on the right side edge once everything is turned and top-stitched.  The reduction from 2 7/8″ between the seams to 2 3/4″ on the right side is the result of what is called the turn of the cloth.  When the 3 inch foam is inserted the compression of the foam (3 inches down to 2 3/4 inches) keeps enough tension on the fabric to keep it all flat and parallel, and the edges and corners round nicely.  Pin and sew the edge strip to the top and bottom. There will be a large opening at the back where the zipper is to be installed.

Finishing the cushions1-resized


I used separating zippers with large plastic coils, again purchased at Dressew, that were slightly longer than the back length of each cushion. The zipper strip is made by sewing a piece of fabric to each side of the zipper tape, right sides together.  Then fold back the fabric strips, exposing the zipper coils and topstitch in place. It works best to start with cloth pieces that are wider and longer than the finished width and length by about 2 inches.  After the zipper was sewn into the cloth strips, I recut the width and the length to get perfectly straight edges and the exact width that you need.  The zipper strip should be the same width as the edge strip and it should be a couple of inches longer on each end so the zipper tucks under the finished edges of the edge strip as shown below.

Zipper closeup-resized


Once the edge strip and zipper strips are sewn in place I serged everything together.  Sunbrella fabric frays easily so serging gets that under control.  For people who don’t have a serger, pinking the edges will also alleviate the fray problem.

Zipper closeup inside 2-resized



Finished cushions-resized

Anyway, I am happy with the result.  Two of these cushion covers have already been removed and washed, and they are indistinguishable from the one that was just completed.


Materials for this project:

4 meters medium weight Sunbrella fabric in Saphire Blue purchased from JT’s Outdoor Fabrics

4 meters athletic mesh fabric

Two 32″ and one 34″ zipper purchased from Dressew in Vancouver, but also available at JT’s

Polyester rot-proof upholstery weight thread by Gutermann

One queen size polyester fibrefill quilt batt.

3 inch high density upholstery foam.  If the cushions are going to be in the rain and weather, then open cell outdoor foam might be a better choice.  Water will run right through it.  Upholstery foam could hold the water for a while.

Size 12(80) topstitch needles – the top stitch needle has a longer eye that definitely helps my machine handle the thicker fabric and thread- I had to change the needle once for this project…when the  needle becomes dull and used up the stitches become sloppy and loose.