Installing a Foil Assist: assembly, adjustments, and compatibility

Electric foil assist changes everything: effortless take-offs in light conditions, long-distance pump foil sessions, surfing tiny 30 cm waves, and easy dock starts from any pontoon. The Duotone Foil Assist 2026 delivers this boost exactly when you need it. Once you're up on the foil, simply cut the motor and enjoy pure, unassisted glide. Duotone has released 8 official videos covering everything you need to know. We've gathered them here, along with the precise instructions from the 2026 user manual.

System Architecture

Three Motorized Mast Versions

The eMast AL (84 cm) features a motor positioned 17 cm below the plate. It is compatible with over 10 brands using the correct adapters. For the lightest and stiffest option, the eMast D/LAB carbon (84 cm) uses a 3BS connection and is exclusively compatible with Duotone and Armstrong. The eMast AL Cruise (80 cm)The motor is placed lower, 15 cm above the fuselage. This makes it ideal for beginners and flat water. This version also includes a propeller guard. All masts accept standard US rails.

eHarness + Watch Ring Remote

The battery is carried in the e-Harness, not in your board. The receiver is integrated into the battery box lid. This ensures stable transmission even in the water. The waterproof Watch Ring remote wears like a watch and includes a finger ring. Double-click the + button to activate, then hold + or − to adjust your speed. The motor stops and returns to 0 as soon as you release the button.

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1. What's Included in Your Kit

Your kit arrives in 5 boxes. Please check the inventory upon receipt:

• Box 1, eMast Set: motorized mast (AL, D/LAB, or Cruise AL), motor bell, plastic propellers (mounted + spare), internal cable, safety leash.
• Box 2, eHarness Set: harness with watertight battery box + neoprene bag.
• Box 3, eRemote Watch Ring Set: remote watch + USB-C cable, finger ring, XL strap, and spare S cushions.
• Box 4, Battery Charger Set: dual charger with fan + 4 power adapters (EU, US, AU, UK).
• Box 5, Battery Set: 2 batteries (30-60 min range) + protective caps.
• Please note, the following items are not included: the Watch Ring's USB-C wall adapter, third-party fuselage adapters, and optional aluminum propellers. The propeller guard is only included with the Cruise version.

2. How to Assemble Your Foil Assist

Your initial assembly involves attaching the mast, fuselage adapter, managing the cable, and setting up the harness and battery. Always run through the pre-water checklist. Motor vibrations can loosen screws, so always check their tightness before each session.

• For the mast screws on the rails, use 4× M8x25, TX45, 15 Nm. The fuselage adapter (AL + Cruise only) requires 3× M8x50, TX45, 15 Nm. Secure the cable with 2× M6x30, TX30, 10 Nm.
• The V-fastener needs to be glued (using 3M adhesive, a one-time application): clean with alcohol, dry, press for 30 seconds, and allow it to cure overnight. The removable V-clip should be attached and removed for each use to secure the cable.
• Before entering the water, ensure the harness/cable connector's twist-lock is fully engaged; this is mandatory to prevent electrical risks. When connecting the motor, align it with the notches and never force it.
• For downwind boards or those with long tails, combine a bungee fastener with the V-fastener to keep the cable clear of the propeller. Always replace the protective caps when connectors are not in use.

Never run the motor out of water, as it will overheat. The magnets are powerful, so never place your fingers between the bell and the plate.

3. How to Maintain Your Foil Assist

Every session in saltwater impacts your gear. The lifespan of your motor, bearings, and connectors directly depends on proper post-session rinsing and lubrication.

• Rinse the harness and battery box while it's closed with the cable attached. Never open the box when it's wet.
• Remove the motor bell, rinse the interior and bearings, then thoroughly dry everything with a microfiber cloth.
• For motor lubrication, use 2-4-C marine grease. For the bearings, use WD-40 Specialist Penetrant only; never use classic WD-40, as it can damage the seals.
• For wet connectors: rinse them, use compressed air, dry thoroughly, then apply a thin layer of dielectric grease. Always replace the caps.

4. Using Your Batteries and Charger

These specific LiHV batteries deliver 7 Ah, 22.8 V, and 159.6 Wh, weighing 1 kg each. You need two batteries to power the system. The capacity is intentionally limited to 159.6 Wh to stay just under the 160 Wh airline limit, though airline approval and a fireproof bag are still required for travel.

• When charging, ensure your charger and connectors are dry. Always charge in a ventilated area and under supervision. Red dock buttons indicate charging, while green means charging is complete. Battery LEDs show charge levels: 1 LED for 25%, 2 for 50%, 3 for 75%, and 4 for 100%. Both batteries will fully recharge in approximately 45 minutes.
• After a session, wait 30 to 60 minutes for the batteries to return to ambient temperature before charging. Never charge a hot or cold battery. You'll reach full capacity after 3-4 cycles.
• Always use storage mode after each session, aiming for 2-3 LEDs (40-60% charge). Leaving a battery empty or full for extended periods will degrade the cells. Perform a complete cycle at least every 3 months.
• Store your batteries at 10-25 °C, never in direct sunlight or on hot sand, and always in a fireproof bag. You'll get optimized range with a front wing ≥ 900 cm² and a board ≥ 35 L.

5. Charging Your Watch Ring Remote

Your Watch Ring remote is watertight, but only if you consistently check the O-ring. This crucial step is often overlooked, yet it's what ensures watertightness during your sessions.

• Charge your remote using a USB-C wall adapter (not included) and ensure the remote is completely dry. The screen turning off indicates charging is complete, so unplug it immediately.
• Before reattaching the ring cable, verify that the O-ring is properly seated around the connector. If the O-ring is missing, your remote will not be watertight.
• The ring cable pivots up to a maximum of 180°; avoid forcing it beyond this limit. Clean the connectors with a dry cotton swab. Charge your remote at least every 3 months.

6. Resetting Your Remote

If you lose connection, this procedure will put your Watch Ring back into pairing mode. You must finalize the pairing within 20 seconds of turning on the batteries.

• To reset, hold the POWER + plus button simultaneously until the screen flashes, indicating pairing mode.
• To turn on the batteries, press both battery buttons simultaneously for 3 seconds. Complete the pairing within 20 seconds, or you'll need to restart the process.
• Upon success, the remote vibrates and displays battery levels. A crossed-out icon in the bottom right means no connection, so re-pair. Keep your Watch Ring off when on the beach.

7. Standard Mode or Boost Mode

Choose between two modes based on your skill level: Boost (7 speeds, default) for maximum power, ideal for challenging take-offs and downwind runs, or Standard (5 speeds) for linear power delivery, which we recommend for beginners.

• To switch modes, press − and POWER simultaneously to toggle between Boost and Standard.
• To activate the motor, double-click + (this is a safety feature to prevent accidental starts). Hold + to accelerate and − to reduce speed.
• Releasing the button stops the motor and returns it to level 0. Standard Mode offers better range and control for your initial sessions.

8. Attaching the Propeller Guard (Cruise Version)

This safety component is exclusive to the Cruise AL version. It's essential for learning and in crowded areas, as your feet and hands can get close to the propeller during falls.

• Always disconnect the battery before any manipulation. Remove the bell and propeller by pulling straight out.
• Remove the motor screws (3× M4x10, TX20) without removing the entire motor. Attach the guard with 3× M4x14, TX20 + medium threadlocker, 3 Nm.
• After assembly, check that the bell spins freely and that the blades do not touch the guard. This guard is incompatible with standard AL and D/LAB masts.

9. Changing Your Propeller Blades

Propeller blades wear out and can be damaged by impacts. Replacement is quick with an M4 Allen key; transferring the seals is the key step.

• Disconnect the battery. You'll need these tools: 2× M4x35 + washers + M4 nuts, Allen key #3/M4, 3 Nm.
• Transfer the seals to your new blade. Blades are marked 1 and 2, so make sure they match. Double-check that the notches are stacked correctly for smooth folding.
• Plastic blades come standard. They offer a lightweight feel and good damping. For more thrust, opt for the aluminum blades, though these are best for experienced foilers. If you find a cracked blade, replace it immediately.

10. Motor Replacement

Should you experience an impact or a motor failure, you can replace the motor module right on the spot. Just make sure you're in a clean, dry environment.

• Always cut power and disconnect the battery first. You'll need these tools: 3× M4x10, TX20, medium threadlocker, and a torque setting of 3 Nm.
• When disconnecting, always pull straight out. Never twist, as this helps maintain watertightness. Before inserting, verify the alignment of the mast/motor inserts and ensure the seal is correctly positioned.
• Apply medium-strength threadlocker (Loctite Blue 243) to the screws. Perform a dry test for a maximum of 3 seconds before getting back in the water. You can find a complete step-by-step guide in the Duotone Helpcenter.

11. Cable and Connector Replacement

The connector is secured to the top plate of the mast with four screws. If your cable is damaged, you can transfer it to a new mast or replace the entire cable assembly.

• You'll need these tools: 4× M4x12, TX20, and a torque setting of 3 Nm. Keep your connectors clean and dry. If they're exposed to sand, salt, or water, apply a thin layer of dielectric grease.
• Push firmly to ensure the male and female plugs are fully engaged. Use moderate torque to avoid crushing the seals.
• Perform preventive inspections on the cable sheath and check the tightness of all four screws, especially after intense sessions. A cracked sheath requires immediate replacement to prevent short circuits and ESC damage.

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FAQ: Duotone Foil Assist

Sources: Duotone Sports, How To Videos Foil Assist 2026 and the official Duotone Foil Assist 2026 user manual. Compiled and formatted by GlissEvolution.