Freedrive — Open Foil Assist

A lightweight, open-source electric foil assist system for riders who want help getting on foil without turning their setup into a full e-foil.

Built in the open, tested in real water, and continuously improved with community feedback.

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Why Freedrive

• Assist, not full propulsion: designed for starts and recovery, not long-distance motoring.
• Low-drag architecture: slim under-board pod concept.
• Open hardware workflow: CAD, print files, wiring, and VESC configs are in this repo.
• Field-proven iterations: developed through long-term testing and community builds.

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Latest verified updates (Feb 2026)

From the build thread on foil.zone:

• Post #149 — Good results with EVA foam seals and move to titanium screws after M8 stainless fastener failures.
• Post #150 — New build assembled in Corsica with RS50 tabless cells (5.15Ah) and custom blade work/testing.
• Post #152 — Clarification that the project needs no CNC: parts are printable at home or via services; material guidance shared for each major component.

Links:

• https://foil.zone/t/light-assist-season-3/24787/149
• https://foil.zone/t/light-assist-season-3/24787/150
• https://foil.zone/t/light-assist-season-3/24787/152

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System snapshot (V4 family)

| Feature | Specification | | :--- | :--- | | System voltage | 12S | | Battery current | 50A | | Phase current | 125A–150A | | Power | ~2200W (6384 120KV reference setup) | | Weight | ~2.8kg (controller, pod, battery) | | Expected starts | 10 to 30 (depends heavily on rider/foil/board/conditions) | | Standard battery | 12S1P 21700 | | Assist + one battery cost | ~650€ |

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Who this is for (and not for)

Good fit

• Experienced DIY riders comfortable with electrical + mechanical assembly.
• Downwind / pump / surf riders wanting launch assist.
• Builders ready to tune and iterate.

Not a good fit

• Anyone expecting plug-and-play consumer product behavior.
• Riders wanting long powered cruising (use an e-foil platform).
• Builders unwilling to manage electrical/waterproofing/safety risk.

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Repository map

| Path | Purpose | | :--- | :--- | | ORDER PRINTS/ | Parts intended for print-order workflow (including metal print parts). | | MAKE PARTS/ | Additional parts to manufacture/print. | | WIRE/ | Harness PDF + wiring references. | | PROGRAMM/ | VESC config files and controller programming notes. | | CAD/ | Main STEP and source CAD link. | | BOM of V4 system.xlsx | Bill of materials. | | TODO.md | Current task list / open improvements. | | NEWS.md | Short timeline of recent project updates from the forum thread. |

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Manufacturing guidance (current community direction)

Based on current thread guidance:

• No CNC required for the baseline project.
• Base: aluminum printed (service options cited: Craftcloud / Prototi), with home-print exploration possible.
• Pod: printable (PPA-CF FDM or PA12 SLS).
• Battery box: PETG print + cast-in-place deep-pour epoxy strategy.
• Blades: aluminum printed.
• Hub: PA12 SLS or PPA-CF.

Always validate thermal behavior, waterproofing quality, and mechanical integrity before riding.

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Scope and limitations

Freedrive is designed as a lightweight launch/assist system. It is not intended to replace paddling skill, surf positioning, or proper foil selection.

Known constraints:

• 12S1P travel limitations (airline Wh restrictions).
• Range is limited if motoring heavily.
• Performance depends strongly on total system setup and rider skill.
• This remains a DIY/open project with no warranty, no guaranteed support SLA, and evolving documentation.

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Safety (read this first)

A powered propeller under a board is inherently dangerous.

• Build and test at your own risk.
• Treat every test as if failure is possible.
• Verify sealing, fasteners, electrical insulation, and remote fail-safe behavior before water use.
• Keep clear procedures for arming/disarming and handling around people.

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Media & communication

• Main development thread: https://foil.zone/t/light-assist-season-3
• Instagram: https://www.instagram.com/adam_mercier_fr/
• YouTube: https://www.youtube.com/@bzhwindtalker29

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Credits

Project led by Bzhwindtalker (Adam Mercier) with major value from community testing and feedback on foil.zone.

If you build one, share your version and results in the thread — especially reliability, sealing, thermal data, and ride feedback.