Ultra-high-performance powerboat achieves high weight reduction with carbon fiber sandwich construction of the deck, internal structure and the complete hull surface.   #layup

The 44-foot Mayla 44 powerboat. Photo Credit: Diab Prefab Four Season Room

Divinycell HM foam by Diab (Laholm, Sweden) is being used to construct the Mayla 44, a new ultra-high-performance electric powerboat currently being built at Nova Mare, the marine division of Nova Composites (Dubai, United Arab Emirates).

Due to launch in early 2023 in Dubai, the Mayla 44 is a radical 44 footer that blends classic styling elements with a state-of-the-art composite construction and electric drivetrain. Designed around patented Petestep hull technology, the Mayla uses distinctive-shaped deflectors to push water downwards and to the stern of the yacht, generating energy savings of up to 35% as well as reducing slamming and increasing passenger comfort.

Even with its novel hull design, the Mayla 44’s top speed — at least 70+ knots — required a very lightweight construction in the form of a carbon fiber full-sandwich composite structure. With weight reduction a priority, Diab supplied Divinycell HM 80 and 130 cores in a range of thicknesses for the deck, internal structure and the complete hull surface including the hull bottom. Epoxy prepregs from Nova’s sister company Notus Composites will be combined with a range of woven, stitched multiaxial and unidirectional (UD) carbon fiber reinforcements on either side of the Divinycell HM cores.

Divinycell HM cores have been extensively evaluated in previous Nova projects, with the company also completing a program of mechanical testing to validate the properties of the new Mayla 44 laminates. In-house composite tooling produced from CNC-milled master plugs has been perfected, Diab contends, and the Nova technicians are scheduled to begin prepreg layup and positioning of the first Divinycell core sections in November 2022.

“Divinycell HM core is a great fit for our prepreg process,” Oliver Janaranjana, operations manager, Nova Mare, says. “Not only do we get the high toughness and mechanical properties we need for such a fast vessel, but HM foam also provides excellent bonding with our prepreg resin films, minimal resin uptake and trouble-free processing during our low-temperature cure cycles.”

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Divinycell HM is a high-performance structural core designed specifically for fast marine hulls such as the Mayla 44, where higher toughness is required. It combines a very high shear strength with outstanding shear elongation, Diab says. As a result, Divinycell HM is capable of absorbing the high dynamic impacts and slamming loads generated by modern, high-speed craft. Its elongation reportedly exceeds the requirements of ISO 12215, GL and ABS rules, enabling engineers to create lighter structures without compromising strength or safety.

“We believe that truly sustainable yachts are only possible with radical weight reduction,” Christopher Gelsdorf, co-founder of Mayla Yacht, adds. “The lightweight carbon fiber prepreg sandwich construction we use for the Mayla 44 enables a hull weight of only 1.35 tons (versus more than 4 ton for traditional high-performance yachts) creating less resistance and less drag. Diab’s Divinycell HM was fundamental in enabling those weight savings.”

The structural properties of composite materials are derived primarily from the fiber reinforcement. Fiber types, their manufacture, their uses and the end-market applications in which they find most use are described.

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Compared to legacy materials like steel, aluminum, iron and titanium, composites are still coming of age, and only just now are being better understood by design and manufacturing engineers. However, composites’ physical properties — combined with unbeatable light weight — make them undeniably attractive. 

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