Clever surgery on a standard bed mattress improves a V-berth’s sleepability.

When we bought Phantom, our Pearson 365 ketch, in 2001, my wife, Barbara, and I slept on V-berth cushions so thin and inadequate it felt like we were sleeping on bare boards. Adding a foam overlay was a slight improvement, as was a duvet with several quilts tucked inside, but none of these changes provided a good night’s sleep.


The boat’s original V-berth cushions were too thin to provide enough comfort for a good night’s sleep. The first mattress transplant resulted in a single, 4-inch- thick mattress shaped to fit the V-berth. It worked well but made access to storage beneath problematic.

We had priced custom-made mattresses that fit our V-berth, but we were reluctant to spend that much money on something we felt would be short-lived in the boat environment. Then one day we saw Ingrid, who worked at a canvas shop, doing surgery on a standard bed mattress. Snipping apart springs and cutting the rectangular shape to fit her V-berth, she repurposed the discarded bits to reshape the mattress and sew it back together. None of it appeared too daunting. I’d seen what was possible and was confident I could do the same.


Before making any cuts, Jim used craft paper to create a template of the new split V-berth mattresses on the shape of the full-size mattress.

On the garage floor, I laid out a 4-inch- thick queen-size mattress from a discarded sleeper sofa. Directly on the single-sided mattress, I drew the shape of the V-berth with a magic marker. My lines made allowances for where I would need material for the re-sewing process, and before cutting I carefully unstitched the seam material I’d be reusing.


Jim transferred the template to the mattress, using markers to outline where to make the cuts.

The mattress interior consisted of an outer cover, foam, padding, and “tubes” of coil springs. I disassembled and discarded the springs that would lie outside the new V-berth shape and securely tied together the remaining springs. After sewing shut the padding and cover, we put the newly shaped mattress on top of the existing V-berth cushions and slept like babies.


The initial cut exposes the mattress’ foam; the springs are beneath this layer.

That was 12 years ago, and all has been well except that in making that big, single-piece mattress, we failed to plan for accessing stowage areas under the V-berth. We’ve lived with it, but it was finally time for a new and improved version.


Once the foam layer is pulled back, the springs are ready to be cut.

This time around, rather than a single mattress, I planned to make two side-by-side mattresses that fit our V-berth. Instead of a single-sided, 4-inch sleeper sofa mattress, we started with a standard 8-inch, full-size, double-sided mattress. Since either side of the new mattress could be a top, I could cut it on the diagonal and make both V-berth halves from the single mattress by flipping one half over after cutting the mattress apart.


The springs, fully exposed, are ready to be cut to fit the new shape of the mattress.

I created paper templates of each side of the V-berth mattresses to move around on a paper template of the full-size mattress. I drew the planned shape of the new V-berth mattress on the double mattress with a magic marker, and a mark between these shapes became the line to cut the cover open. I made the cut gently to preserve all available materials, padding, and foam. Carefully, I exposed the springs and cut them using a bolt cutter, then separated the two halves.


Once the diagonal cut was fully made, Jim separated the mattresses, which already resembled their intended new shapes.

Once I flipped one half over, the 76-inch sides lay together to create the V shape. I trimmed the springs and wired them to fit into the desired configuration. I bent and secured all the ends, making sure that no sharp metal pieces remained that could work their way to poke out of the mattresses. Then I securely wired the springs together to maintain the shape and structural integrity of the mattresses.

Next, I added foam and batting to create a smooth, comfortable side and corners. I hand-stitched lightweight cotton canvas as the new side panels.


The newly rebuilt mattresses, waiting to be installed.

This two-piece, 8-inch-thick mattress is even more comfortable than the first 4-inch mattress we fabricated to place over the boat cushions. It’s still a bit inconvenient to access the storage beneath—when you flip one side up, the bed clothes get messed up and need to be rearranged—but it’s easier than lifting or removing an entire mattress.

As to whether the mattress would with- stand the boat environment, we used the original 4-inch mattress for 10 years without rust, mold, mildew, or water saturation issues, and the new mattress is holding up fine so far. Just in case there are any unexpected leaks, we protect the bedding with a waterproof cover when we are absent from the boat for any period of time.


The new, 8-inch, split V-berth mattresses fit perfectly. And, one side can be lifted to access storage beneath the bunk.

Except for the price and the reality that I’m not a professional upholsterer—and the finish on the seams and cut sides of the mattress reflect this—these mattress- es are nearly identical to the expensive custom-manufactured V-berth mattresses sold today. I’m not a master craftsman, just a guy handy with common tools. I recommend anyone in need of a more comfort- able night’s sleep aboard to get in there and give this a try.

Tools and Tips

The interior construction of mattresses will vary, but a thoughtful analysis of the construction technique will determine what will be required to arrive at the desired shape. Inner spring mattresses have a pattern of coil springs that are secured by clips and smaller coil springs. Measure twice, cut once, and have Band-Aids ready: Those cut spring ends are are very sharp! I’m unfamiliar with foam mattress construction but no doubt these can be cut to size as well.

I recommend making the mattress a little oversize if fitting it into a space like a V-berth; you can always go back and trim it down more if needed. Additional foam and batting may be needed to fill any edge and corner voids; these are readily available at craft stores like Michael’s, Hobby Lobby, and JoAnn Fabric and Craft.

Tools and materials required : a bolt cutter; side-cutting pliers;  wire-twisting pliers; iron wire; foam  and batting; needle and thread; scissors;  rulers; tape measure; marking pencils; and magic markers.