Matt Steverson Boatbuilder Matt Steverson built these lightweight companionway steps from fully recyclable Edura Marine panel made of recycled polyethylene terephthalate (PET) foam sandwiched between skins of PET and glass fiber.
Multihull pioneer Walter Greene kept a deliberately low profile as he built some of the legendary racing sailboats of the last century at Greene Marine, a disarmingly modest yard on the Cousins River in Yarmouth, Maine. A who’s who of multihull designers, builders, and sailors passed through the shop, refining new gear and sailing technologies and learning to build lightweight but supremely stiff and durable composite structures. Those people and innovations enabled modest multihulls to snatch line honors and records from much larger monohulls and eventually to dominate offshore sailboat racing. It was a de facto marine industry incubator before the notion existed. Following Greene’s death in 2024 (See “Farewell to the Multihull Builder” in Professional BoatBuilder No. 211, page 108), it seemed unlikely that I’d encounter any new innovations with Green Marine DNA. Enter Edura Marine to remind us of the long reach and lasting influence of Walter Greene in our industry.
Created by siblings Emily and Ben Davis during the pandemic, Edura Building Systems started as a solution for their storage box rental business at a time when the shipping containers they used became scarce. John Rossi—director of product and design for Edura, as well as its parent Even Keel Group—explained how the resulting foam-cored composite storage boxes were reworked into a second company, OpBox, which provides utilitarian mobile shelter for everything from bottle return shelters, gallery space, and brewpubs to a kelp laboratory.
It was Ben and Emily’s background in boatbuilding, including a shared childhood in the Green Marine yard where their family was involved in building a charter catamaran, that made cored composites rise to the surface as the optimal material for building modular and mobile shelter or storage structures. “The material itself is similar to what you might see in a boatyard today,” Rossi said. “They might take a piece of any type of panel whether it’s plywood, Coosa, or foam, and wet-lay it up and add glass reinforcement to it.”
But the Davises were intent on using recyclable material that would be impervious to the rot that plagues many plywood structures. They turned to Polyethylene terephthalate (PET) foam can be made from recycled drink and food containers, and it’s a stiff, closed-cell structural foam that’s easy to bond protective skins or other structural elements to. They built some of the first fiberglass-skinned panels for OpBoxes with advice from Greene and his shop manager, Charlie Smith. “Walter and Charlie Smith were my sounding board,” Ben Davis said. The boatbuilding veterans knew what composite structures would hold up in extreme conditions, and how they would fail if they didn’t.
After the technology had been proven, they moved panel production to a 15,000-square-foot (1,393.5m2) production facility in Woolwich, Maine. And they refined the materials to eliminate the nonrecyclable fiberglass and polyester resin skins, switching to a PET and glass fiber skin material that comes in a roll and is fused to the foam core in a bespoke press under heat and pressure at a rate of a panel every two minutes.
The result is a structural foam panel that’s roughly half the weight of Coosa and less than half that of Okoume marine plywood and doesn’t require installation of a layer of fiberglass and resin to seal or protect it. Panels come in three thicknesses—1 ½”, ¾”, and ½” (38mm, 19mm, and 13mm)—and two areal dimensions—4′ x 8′ (1.2m x 2.4m), and 4′ x 10′ (1.2m x 3m). Edura can be cut to dimension and shape with basic woodworking tools, and because there’s no amine blush or other production residue on the PET surface, bonding with epoxy or marine adhesives is very secure and requires little surface preparation other than assuring it’s clean. Paint can be applied directly to the linen-textured PET laminate skin without preparatory sanding. That’s all significant labor savings for boatbuilders.
Matt Steverson Edura panels can be curved by cutting kerfs into one side and taping the altered surface with fiberglass and epoxy while the uncut skin bows but remains intact.
The stiff panels can be bent into a slight curve—½” in a 6′ (1.8m) expanse of the ½” stock—without cutting. But with kerfs cut in one side or the other, Edura can be radiused quite dramatically to form curved panels and even bullnose edges to counters or cabin tops while leaving the convex surface layer intact. Raw edges can be closed out with fiberglass tape and resin, or the foam can be routed out and the exposed edge backfilled with epoxy.
Matt Steverson Here, Steverson added a wood veneer to a curved Edura panel.
As a measure of its strength-to-weight ratio, sales representative Graham Fitch pointed to a 10′ flat-bottom work skiff built completely from Edura over a traditional mold from Charlie Smith at Greene Marine. The rugged structure weighs a scant 107 pounds (48.5kg). Fitch and Rossi have taken Edura to more than 40 boatyards, many of them building commercial boats in Maine. Fitch noted the benefits of lightweighting the superstructure and cabinetry on an existing model to offset the burden of additional gear and equipment necessary on modern boats. The 407 series panel, which has four layers of glass fibers in alternating orientations in each skin, is very durable and robust enough to serve as work deck on Maine lobsterboats. Fitch said some builders add a layer of glass over it for impact resistance.
More boatbuilding experience in the Edura shop comes from production director John Vinal, a 40-year veteran Maine builder who worked in wood and composite construction for the storied Gamage and Hodgdon yards, among others.
For some first-hand experience with Edura, I called Matt Steverson, a boatbuilder restoring the Rodger Martin-designed Open 60, Duracell, with his partner Janni Petersen in Port Townsend, Washington (see Dieter Loibner’s profile of the Duracell refit). They are striving to keep the weight of their former racing machine light, even as they build in cruising accommodations that were never imagined in Martin’s original design. They found Edura about halfway through the project.
Matt Steverson Steverson laying out maple countertop material on the Edura structural base for the galley counters.
“It has been extremely helpful for us,” Steverson said. “I was building basically the same thing on a vacuum table.” But with Edura, he saves the panel build time as well as eliminating the consumables—breather cloth and vacuum bags—and the excess epoxy from his process. “It’s a lot less waste for me,” he said. It also saves him time in preparation for finishing including no need to fill the pinholes that were common in his shop-built panels.
Matt Steverson The nearly finished wood counters still reveal their light foam core material, essential to Steverson’s project of building cruising accommodations into the formerly competitive Open 60 Duracell.
Steverson said he’d built an anchor locker, rope lockers, a battery box, a veneered galley counter, and companionway steps, and he’s planning to a bimini top and floorboards as well. Putting them together was straightforward—cutting panels to plan, cutting kerfs where necessary, and taping the elements together with fiberglass tape and epoxy. “I found that the glass tends to tear out a little bit; it frays where you cut it… but if you tape it beforehand, it helps,” he said. It’s akin to preventing wood tear out with painter’s tape when cutting across grain.
Steverson found it essential to use backing plates for mounting hardware and glued wood strips where structural fasteners connect elements like drawer slides to the foam-core material. For painting, he said his preparation is to, “go over it with some 80 grit for a minute just to make sure. But sometimes I haven’t, and it’s worked just fine.”
His only warning to users: “You have to make sure you store it flat.” When stored on edge leaning against a wall or rack in your shop, it will curve slightly and can hold that shape.
Edura Marine, 126 US Route 1, Woolwich, Maine 04579, USA, tel. 207-512-6835, edurabuildingsystem.com
