This video documents the ambitious process of building a 14-foot minimalistic catamaran using 3D printed lightweight PLA sections reinforced with carbon fiber. Motivated by the inefficiency of a previous boat for displacement cruising, the creator designed narrow, efficient hulls inspired by rowing shells, sectioning them for printing. The build involved assembling 40 printed sections, applying extensive carbon fiber and fiberglass reinforcement, dealing with challenges like intricate hull geometry and epoxy application errors (bubbles), and creating a foam-cored, carbon-reinforced deck structure. The boat is powered by repurposed electric motors mounted on custom 3D printed pivoting mounts. Initial testing revealed a top speed of 10 mph and slow turning characteristics, but confirmed hull watertightness and good structural rigidity under load, despite some flex. The creator highlights lessons learned regarding hull design details, composite application, and paint surface prep, concluding with plans for future propeller and efficiency testing.
Building a 3D Printed Carbon Fiber Catamaran
0:00 Motivation: The creator previously used a planing hull boat (Boston Wher) as a low-speed displacement hull for a 125-mile trip, which was inefficient (3.8 mph with 1000W solar). This inspired the need for a more efficient displacement hull design.
0:38 Design & 3D Printing: Decided to build a 14ft catamaran fitting his current workshop space. Designed narrow, efficient hulls (inspired by rowing shells) in OnShape, splitting them into 20 sections per hull (40 total) for 3D printing with lightweight PLA filament.
1:38 Hull Design Features: Added recessed areas for batteries and a "bilge" area, which were later regretted due to difficulty in fiberglassing. Used rectangular cutouts for deck mounting posts.
2:21 Infill Choice: Used gyroid infill for the 3D prints to create one continuous internal volume, making it easier to drain potential leaks (though less buoyant without foam). Backup buoyancy foam was only added to some sections.
3:01 Post-Processing & Assembly: Sanded prints, drilled alignment holes, and cut drainage holes between sections. Glued sections together using Gorilla Glue and carbon fiber rods for alignment, resulting in three larger sections per hull initially.
3:14 Deck Mount Posts: Created wood posts reinforced with fiberglass and carbon fiber, cured under vacuum, to serve as mounting points for the deck.
4:44 Hull Flexibility: Noted the lightweight PLA hulls were not strong enough on their own and would snap if glued entirely before reinforcement. Demonstrated significant bending before adding composite.
6:47 Fairing & Fiberglassing Challenges: Applied epoxy fairing compound to smooth imperfections. Found fiberglassing over the recessed battery/bilge areas difficult and time-consuming due to compound curves.
7:35 Gluing Hulls Together: Glued the three hull sections together on a long table, using straps and shims for alignment, but some sections were not flat due to printing variations.
8:14 Carbon Fiber Reinforcement: Applied unidirectional carbon fiber (uni) along the length of the hulls for fore-aft strength, followed by weave for the outer skin. Used peel ply and a heated tent for curing.
11:57 Carbon Fiber Application Issues: Attempted to wet out the large carbon fiber weave directly on the hull surface, leading to dry spots and bubbles, requiring significant sanding and re-application. Learned the lesson to pre-wet the underlying surface.
14:34 Extensive Sanding: Significant sanding was required to fix composite imperfections and prep surfaces, which was described as terrible and something to be avoided. Fairing compound was used extensively.
15:43 Painting: Used one-part polyurethane topside paint and primer. The initial layer revealed many pinholes in the carbon weave texture, requiring more fairing compound over the primer and extensive sanding before the final yellow coats.
17:07 Second Hull Build: Built the second hull, applying lessons learned (pre-wetting surfaces, lower heat gun temp with peel ply), resulting in a much cleaner composite layup with fewer issues.
18:22 Finished Hulls: Two yellow hulls completed, weighing 13 kg (28.5 lb) and 13.3 kg. Added Goretex membranes in battery wells to prevent pressure buildup.
18:47 Deck Construction: Built the deck using reinforced wood beams, pink insulation foam core, and 3D printed fillets. Reinforced the structure with extensive carbon fiber uni and weave, vacuum bagging sections for curing.
25:41 Deck Handle: Added a 3D printed PETG handle embedded in the deck for easier transport.
26:29 Initial Assembly & Rigidity Test: Bolted the hulls and deck together for a test fit. Noted a loud crack during rigidity testing (possibly connectors slipping) and observed some torsional flex, but seemed strong under vertical load (two people).
27:23 Deck Surface & Painting: Applied adhesive-backed foam for the deck surface and painted the bottom of the deck blue.
27:42 Motor Mounts & Electronics: Designed 3D printed pivoting motor mounts (PETG with flexible filament inserts) to attach repurposed, water-damaged VESC 75200 ESCs and shortened hydrofoil masts with motors to the deck. Repaired and repotted the ESCs.
32:09 Maiden Voyage Prep: Transported the boat components on a truck. Assembly takes a few minutes. Designed 3D printed stands to protect the hulls on the ground.
33:08 Battery Well Bailing: Noted the water line was higher than expected with two people (350lb combined weight), causing some water to enter the battery wells, requiring bailing. Expects better performance with lighter load.
33:27 Maiden Voyage & Performance: Tested the boat with RC control (elevons). Noted very slow turning ("like a container ship") but good straight-line speed. Achieved a top speed of 10 mph based on a phone app reading. Motors were only lukewarm.
35:13 Speed with Lighter Load: Tested with a single person and found the speed didn't significantly increase, attributing this to the nature of displacement hulls at higher speeds.
35:34 Efficiency & Future Propellers: Believes different, more efficient propellers could increase speed and efficiency.
36:01 Motor Failure: One VESC ESC stopped working near the dock, though a backup 5V supply got one motor running temporarily. Noted the history of the water-damaged ESCs.
36:20 Watertightness Confirmed: Re-weighed the hulls after the maiden voyage, confirming no water ingress (weight increase of only 0.3 kg), expressing satisfaction.
36:30 Next Video Plans: The next video will cover testing better propellers, range tests, and efficiency tests.