MAMBO Prototype

MAMBO PrototypeCourtesy MOI Composites

Moi Composites introduced this unusual-looking 3D-printed fiberglass runabout with a hull shape inspired by Sonny Levi’s Arcidiavolo, but unencumbered by the constraints of conventional composites building technologies

In the midst of a pandemic, it was easy to miss the debut of the MAMBO (Motor Additive Manufacturing Boat) runabout, presented at the Genoa Boat Show by Moi Composites Srl, an Italian tech startup founded in 2018 as a spinoff of the Politecnico di Milano University. Working with partners like Auto­desk, Catmarine, Confindustria Nautica, Mercury Marine, Micad, Osculati, and Owens Corning, Moi rolled out a prototype that should make boatbuilders sit up and take note. It is the logical continuation of 3-D printing technology that has been used in tooling and prototyping.

The indigo blue hull of this unusual craft is 21 (6.5m) long and 86 (2.59m) wide, shaped like an “inverted tricycle inspired by the famous Arcidiavolo by Sonny Levi,” according to the press release. This unique shape was intentionally chosen to demonstrate what advanced 3D printing can do when combined with continuous fiber manufacturing (CFM) and fiber placement guided by generative algorithms. If advocates of these emerging technologies are correct, the combination could open a new chapter not just for boatbuilding but for automated composite construction yielding strong, durable, and light structures that can be quickly scaled and customized.

Printing GRP PrototypeCourtesy MOI Composites

The printed parts were assembled into a one-piece sandwich structure without a hull–deck joint.

The boat has a dry weight of approximately 800 kg (1,764 lbs), which is about four to five times heavier than an expertly crafted 21 carbon composite hull but still one-third lighter than a mass-produced fiberglass boat of the same length. Hence the relatively modest Mercury Pro XS 115-hp (86-kW) outboard powering this craft. Add­ing the motor’s weight of 163 kg (360 lbs), plus batteries, fuel and water tanks, the MAMBO tips the scales at approximately 2,550 lbs (1,200 kg), “in line with a traditional 6.5m boat,” Moi said.

CFM, not AFP

“We thought that this particular hull, appreciated for stability and performance, was perfect to design something never seen before, adapting functionality and design thinking without the constraints of…conventional technologies [like] draft angles, undercuts, hull and deck division,” Moi’s CEO, Gabriele Natale, said.

MAMBO PrototypeCourtesy MOI Composites

Equipped with proprietary CFM technology, 3D printing robots produce composite structures made of continuous fiber and thermosetting resin. Working along multiple axes, the robots changed fiber orientation to create custom products and structures.


“We only used robots equipped with our proprietary technology, called CFM, a new 3D-printing system, to produce advanced composites made of continuous fiber and thermosetting resin. [It] can be adapted to every kind of CNC machine having more than two movement axes, but since composites are anisotropic materials, performance…strongly depends on fiber orientation. Using multiple axes, it is possible to change their direction in pointwise fashion, thus creating smart, customizable products and structures hitherto unobtainable.” One of the keys was the use of software algorithms for predictive planning of machine movement to deposit reinforcing material in high-stress areas. Moi added a workflow via Autodesk’s software to deliver the necessary information to the robot and control it.

Automatic fiber placement (AFP) is different, Natale pointed out. “CFM technology is not a fiber-placement machine but a hybrid solution between AFP and 3D printing in which fibers are impregnated and deposited by numerically controlled machines in a precise and repeatable manner.” To that end, Moi and Owens Corning developed custom filaments composed of E-glass fiber impregnated with a formulation of vinyl­ester resin. “Once deposited from the print head, the material is irradiated by a dedicated poly­merization apparatus, which quickly cures the matrix,” Natale explained. “This real-time curing system, absent of any models and molds, cuts costs and removes the break-even point.” In other words, it’s no longer necessary to make many copies of the same piece, but each piece now can be different without running up the tab for new molds.

MAMBO PrototypeCourtesy MOI Composites

The prototype had to be printed in 50 parts, which might be reduced to as few as one in the future.

The building process was a hybrid between robotic printing and manual labor by humans. The boat comprises 50 parts printed by multiple machines—two KUKA Quantec high-accuracy robots in Milan, at Moi Composites’ headquarters, and in Autodesk’s Advanced Manufacturing Facility in Birmingham, U.K.—another advantage of 3D printing. Assisted by Micad, the project’s marine engineering partner, the printed pieces were assembled at the Catmarine yard in Miggiano, Italy, creating a one-piece sandwich structure without a hull–deck joint. Each individual section was laminated with a PVC core, polyester resins, and fiberglass fabrics, creating the layers and reinforcement structures that then had to be joined. For a glossy finish, Moi turned to old-fashioned elbow grease—workers sanding the surface before fairing and priming it for gelcoating. “This was the most critical part of the project, because it required a lot of time in a compact schedule,” Natale pointed out. “Working with the artisans, we believe we can improve this step for the next product.” Since CFM technology is scalable, Natale also was confident that the next-iteration boat might get printed in as few as six parts, using a bigger robot and a larger facility. “Our ideal target is to enlarge the machine size even more to print our future MAMBO 2.0 project in one shot,” he said.

MAMBO PrototypeCourtesy MOI Composites

Finally, the printed structure was sanded, faired, and primed by hand

Finally, the word moi is Italian slang for “now.” On its Facebook page, the company suggests it sums up the “determination to overcome uncertainty and start doing something awesome.” Like using 3D printing technology to break some constraints of mold-making—the high investments of time and money and the limitations of buildable shapes. With this runabout project, the firm set out to show it is possible to design and build a boat with a cored laminate and cavities in the hull shape that would be difficult or impossible to create with conventional building methods. Another benefit of this technology, Moi says, is reducing weight and waste by optimizing the position and the direction of the fibers. And that doesn’t apply to boatbuilding alone.

Moi Composites Srl, Via Bergamina 25, 20016 Pero MI, Italy, tel. +39 (0) 3756550137.