The Duotone Foil Assist Set AL is the heart of the Duotone electric range – a slim 84cm aluminium mast with a fully integrated motor pod and folding propeller, powered by two compact 7Ah batteries carried around your waist in the dedicated eHarness.
By keeping the batteries off the board and putting the motor into the mast, the system keeps your board light and surfy. You’re not riding a heavy e-foil; you’re still riding your real foilboard and favourite wings, just with a smart boost whenever you need it. Hit the trigger on the eRemote Watch Ring and the Assist helps you get up in marginal wind, recover blown take-offs, link more waves and cruise back upwind without grinding your legs to dust.
Key specs
- Mast: 84cm Foil Assist Mast AL with integrated motor pod and folding plastic propeller
- Motor thrust: approx. 33kg
- Batteries: 2 × LIHV 7,000mAh 22.8V, approx. 159.6Wh each, ~900g per pack (2 required to run)
- Remote: Watch-style eRemote Ring – displays speed, system battery, remote battery and connection status
- Harness: eHarness waist belt, buoyant, non-water-absorbing, magnetic connection and quick-release
- S–M: 71–89 cm / 28″–35″
- L–XXL: 89–114 cm / 35″–45″
- Mounting: Standard US foil tracks on the board
- Recommended minimum board: ~35L midlength foilboard
- Recommended front wing: 900cm² or larger for best efficiency
- Disciplines: Wing, prone surf, downwind, pump, wake, freeride
What’s in the box
Exact contents may vary slightly by region, but a typical Foil Assist Set AL includes:
- Foil Assist Mast AL 84cm with motor pod, folding plastic propeller, mast cover and propeller protector
- eHarness Set (harness + battery box) in chosen size range (S–M or L–XXL)
- eRemote Watch Ring Set (watch, ring, charging cable)
- Battery Charger Set (Smart Charger)
- 2 × Foil Assist 7A batteries plus padded battery bag
- Main top plate + board mounting screws and basic tools
- Cable & leash between battery box and mast
- Cable fastener V and cable fasteners (4 pcs) to route the cable neatly
- Extra propeller blades – regular (2 pcs)
Battery runtime and charging
Runtime depends on rider weight, board, foil and how hard you lean on the motor, but Duotone’s own reference setups (Midfish boards with Glide 900/1100/1350) show around 45 minutes of assisted use at a mid-range speed for riders in the 70–100kg range.
Tweak your gear and usage and you’re realistically looking at about 35–55 minutes:
Lighter riders, larger / more efficient foils, moderate speed → nearer the 55 min end.
Heavier riders, smaller / faster foils, high speed settings → nearer the 35 min end.
The Smart Charger delivers fast charge in roughly 45 minutes, depending on how empty the packs are. With sensible storage and charging habits, you can expect around 300–500 cycles from the batteries.
Travel and airline use
Each battery sits at roughly 159.6Wh, deliberately just under the commonly used 160Wh airline limit. That makes the Foil Assist platform one of the few realistic options for destination trips: in principle you can fly with the packs as hand luggage, as long as you follow airline rules for lithium batteries (carry-on only, taped / protected terminals, quantity limits and any carrier-specific approval).
Foil compatibility and adapter fuselages
Out of the box, the Foil Assist Mast AL bolts into standard US foil tracks. With Duotone’s adapter fuselage range, you can run most of the major foil brands you already own:
- Duotone
- F-One
- Gong
- Axis
- Lift
- North
- Code
- Sabfoil
- AFS
- KT
Plus the dedicated eFuselage Armstrong to bring Armstrong wings into the system.
So instead of buying a whole new foil ecosystem, you can treat the Foil Assist mast as the powered engine under your existing quiver.
Safety, ergonomics & harness sizing
The folding prop opens when you pull the trigger and closes when you release it or fall, cutting the motor and reducing drag and risk around your foil. The eHarness is built from buoyant, non-water-absorbing materials so it doesn’t get heavy or sag in the water, and the magnetic connection + quick-release mean you’re never locked in.
Getting the right eHarness size is important for comfort and control:
S–M (71–89 cm / 28″–35″) – slimmer riders, teens, lighter wetsuits.
L–XXL (89–114 cm / 35″–45″) – broader waists, thicker winter suits or those who like more overlap.
A snug, secure fit stops the battery box shifting during pumps, carves and crashes, so the system feels like part of your body rather than something flapping around behind you.
Who it’s for
The Duotone Foil Assist Set AL is aimed at intermediate and advanced foilers, plus confident improvers who are close to flying consistently:
- Wing foilers who want more sessions in marginal wind without upsizing to massive boards and wings.
- Prone surfers who want help getting into waves on smaller, more performance-oriented boards.
- Downwind and bump riders who like the idea of downwind vibes without committing to brutal paddle-ups.
- Pump and wake foilers who want to extend sessions and experiment with faster, more efficient gear.
- If you want to foil more often, on smaller kit, in more conditions, without losing the feel of a pure foil setup, this AL set is the sensible starting point.
Why it stands out
- Mast-integrated motor + waist-mounted batteries – light, low-drag and natural feeling compared to full e-foils.
- Thought-through battery spec (159.6Wh) that’s friendly for airline rules.
- Massive foil compatibility via adapter fuselages – electrify Axis, Lift, F-One, North, Code, Gong, Sabfoil, AFS, KT and Duotone foils.
- Aluminium mast gives a great balance of price, performance and durability, and you can always upgrade to D/LAB later while keeping the same electronics.
Why buy from The SUP Company
At The SUP Company we’re already using the Foil Assist AL set with Midfish, Midfish Air and multiple foil brands in real UK conditions. We can help you:
- Decide if the AL set or D/LAB is the better starting point for your budget and goals.
- Choose the right eHarness size (S–M vs L–XXL) based on your body size and typical wetsuit thickness.
- Match the Assist mast to the right board, foil and adapter fuselage for your Axis, Lift, F-One, North, Code, Gong, Sabfoil, AFS or KT wings.
- Set realistic expectations for runtime, charge routine and learning curve, so the Foil Assist actually solves the problems you’re trying to fix.
