Foil Assist Explained: Foil Drive MAX+, Fusion, Duotone and Waydoo
Foil assist adds controlled electric propulsion to a hydrofoil setup, making it easier to build board speed, take off and recover from a touchdown. For some riders that means more waves. For others it means finally getting reliable downwind starts, practising flatwater pumping or getting a smaller wing board moving in marginal UK wind.
The main buying decision in 2026 is no longer simply Foil Drive Gen 2 versus Duotone. Foil Drive Assist MAX+ Gen 2.5 now replaces the original Assist MAX as the current all-rounder, while Foil Drive Fusion offers a higher-capability Gen 2.5 alternative. Duotone Foil Assist and Waydoo FoilBoost provide genuinely different approaches.
At The SUP Company we supply and advise on all these routes. Our job is to help you match the whole setup to your riding, rather than sell the biggest motor by default.
Which foil assist should you buy? The quick answer
- Foil Drive Assist MAX+ Gen 2.5: our first comparison point for most existing foilers who want strong, versatile assistance across surf, downwind, wing, wake and flatwater.
- Foil Drive Fusion: for riders putting greater emphasis on power and extended powered use, especially heavier riders or an eFoil-style crossover.
- Duotone Foil Assist: for a tidy integrated motor mast, batteries worn off the board and a particularly natural foilboard feel.
- Waydoo FoilBoost: an alternative retrofit-style foil-assist route for existing foilers balancing capability and purchase cost.
- Original Foil Drive Assist MAX / Slim Gen 2: still useful to existing owners and appropriate older-system buyers, but these are not interchangeable with MAX+ batteries and chargers.
What is foil assist, and how does it differ from an eFoil?
Foil assist is normally about using the motor to get flying and then reducing or switching off the power so the foil can work as intended. Riders use it for wave entry, lulls, restarts, short powered sections and repeated training runs. A full eFoil is designed around sustained motor-powered flight, often with a purpose-built board and propulsion system.
There is overlap. Some powerful assist systems can be configured for prolonged powered use, and some foil-assist riders rely more heavily on throttle than others. But a powered system never removes the need to learn safe foil control, appropriate conditions and good judgement.
Foil assist systems compared
| System | Physical layout | Choose this if | Check before buying |
|---|---|---|---|
| Foil Drive MAX+ Gen 2.5 | 43V under-board battery system; retrofit or compatible integrated mast options | You want versatile, strong assistance and manageable system size | Board underside clearance, pod, motor height, FM+ battery |
| Foil Drive Fusion Gen 2.5 | 43V under-board system, larger-battery capability | You prioritise greater powered performance and runtime options | Board fit, installed weight, battery/adaptor configuration |
| Duotone Foil Assist | Integrated motor mast; batteries in waist harness | You want to keep battery weight off the board | Foil-brand adapter or fuselage and harness sizing |
| Waydoo FoilBoost | Retrofit-style mast propulsion system | You want an accessible assist route around existing gear | Mast section, mounting compatibility and actual riding aim |
| Foil Drive MAX / Slim Gen 2 | Older-generation under-board assist systems | You already own compatible hardware or find suitable previous-generation value | Gen 2 batteries, charger and parts compatibility |
1. Foil Drive Assist MAX+ Gen 2.5: the current all-rounder
MAX+ builds on the highly successful original Assist MAX but moves onto Foil Drive’s newer approximately 43V Gen 2.5 electronics. Foil Drive describes roughly 20% more thrust and power than the earlier MAX, alongside a smart battery system, more consistent performance and faster charging.
Current MAX+ configurations use the 648Wh FM+ 650. Foil Drive quotes up to 35.5kg thrust in the relevant configuration, but there is more to the riding experience than a single figure. The board, foil, propeller, motor position, rider weight and riding technique determine how effectively that power gets you flying.
MAX+ is a particularly sensible choice for an experienced foiler wanting more useful riding time without making full-time electric cruising the primary goal. See the Foil Drive MAX+ product and motor options.
2. Foil Drive Fusion: when extra capability matters
Fusion shares the Gen 2.5 architecture but sits above MAX+ for riders with bigger power and battery demands. Its 864Wh Fusion 860 battery is particularly relevant to sustained riding. Alternatively, the FM+ 650 battery can be used in Fusion with the correct FM+ Battery Adaptor.
That choice is useful if you want a more powerful system but do not always need to fit the biggest battery. The trade-off remains the physical size, board fit and weight of the propulsion setup. Read the MAX+ versus Fusion comparison before paying for capacity you may not use.
3. Duotone Foil Assist: integrated mast, different feel
Duotone takes a different approach, with the motor integrated into the mast and the batteries carried in a waist-worn eHarness. This reduces the battery mass carried by the board and helps preserve natural board response. Aluminium AL and premium carbon D/LAB versions cater for different budgets and performance priorities.
The important checks are foil compatibility, the right adapter or dedicated fuselage and the handling of the belt, remote and connection. A Duotone integrated mast should not be judged as though it were simply a Foil Drive with a differently shaped battery.
Explore Duotone Foil Assist Set AL or read Duotone vs Foil Drive MAX+ and Fusion.
4. Waydoo FoilBoost: a different retrofit route
Waydoo FoilBoost is designed to add assistance to compatible existing foils. It has its own mounting, dual-battery and remote arrangement; it should not be treated as a battery-compatible alternative to Foil Drive or Duotone. It is worth considering if you already foil and want help with take-offs without stepping straight into the highest-value setups.
As always, confirm mast dimensions and the exact package contents. See the Waydoo FoilBoost kit.
What happened to Foil Drive Gen 2?
The original Assist MAX is an established and capable system. Owners with working batteries, chargers and accessories may get better value from maintaining or selectively improving their existing setup rather than replacing everything.
However, MAX+ and Fusion run a different 43V battery family. Original Gen 2 batteries and chargers are not compatible with the MAX+ platform. Do not assume a battery, charger, motor or accessory is interchangeable because both products carry the Foil Drive name. Our battery compatibility guide breaks this down by system.
Recommendations by rider type
Experienced surf and prone foiler
Start with MAX+ if you want more wave entries and repeat sessions. Choose Duotone if integrated mast feel is a priority. Consider Slim Gen 2 only with a clear understanding of its lighter-assist limitations and generation.
Downwind SUP or flatwater pump training
Choose a board that accelerates easily, a foil sized for your weight and enough boost to make repeated starts realistic. MAX+ is a versatile starting point. Fusion becomes attractive if you depend on the motor more heavily or need additional powered support.
Heavier rider or demanding flatwater starts
Compare MAX+ and Fusion carefully, rather than assuming that the first foil-assist kit you see will be enough. At roughly 90–100kg and above, board efficiency and available power become particularly important. These are only broad starting points; see our rider-weight setup guide.
Wing foiler dealing with light wind
A motor can help a smaller board break free, but it should be paired with a suitable wing and front foil. Choose the package that improves take-off without making normal riding unnecessarily heavy or complicated.
Brand-new foiler who primarily wants powered flight
A dedicated eFoil may be the more straightforward learning direction. Foil assist is most rewarding when you intend to learn or already possess the skills to foil without continuous throttle.
How to choose your board, foil and motor height
Motor assistance does not compensate for every poorly matched board. A suitably efficient mid-length board and a front foil with appropriate lift often do more for the experience than moving automatically to maximum throttle and a tiny front wing.
With a mast-mounted motor, a higher position normally clears the water sooner once flying, reducing powered-component drag. A lower position offers longer motor engagement through take-off and touchdowns, at the cost of more submerged hardware. Cable length and motor position also need checking differently on certain integrated and Fusion installations.
Try the right setup before you buy
Our Lymington Try It Now service is designed for serious buyers who want sound setup advice and the possibility of trying selected technical equipment. Foil-assist demonstrations are subject to suitability, availability and approval. Ask us about the exact system you want to compare rather than assuming every model will be ready to demo.
Finance options are available on qualifying orders, which can be useful when investing in a complete setup. See the current finance options. Delivery and lead times depend on the chosen package and variant; contact us if timing is important.
Foil assist FAQs
Is Foil Drive MAX+ a new version of MAX?
Yes. MAX+ is the newer Gen 2.5 all-round system. It is a different electrical and battery platform, not a renaming of the original Gen 2 MAX.
Which Foil Drive should I buy first?
For most existing foilers buying a new system, compare MAX+ and Fusion first. Choose MAX+ for versatile foil assistance; Fusion for additional powered performance and larger battery options.
Can MAX+ use my old Gen 2 MAX battery?
No. The generations use different battery and charging architecture. The newer FM+ 650 can be shared between MAX+ and Fusion with the appropriate Fusion adaptor.
Is Duotone better than Foil Drive?
Neither is universally better. Duotone prioritises an integrated powered mast and batteries off the board; Foil Drive offers a modular under-board system with different power and battery choices.
Does a heavier rider always need Fusion?
No. Rider weight is one factor alongside board and foil efficiency, experience and how long you want to motor. Fusion deserves comparison where take-off demand or sustained powered riding is high.
Can beginners use foil assist?
Yes with suitable equipment, instruction and conditions, but electric power does not replace safe foil technique. Someone mainly wanting powered cruising may be better suited to a purpose-built eFoil.
Can I try foil assist at The SUP Company?
Selected technical demos may be available at Lymington, subject to rider suitability, equipment availability and approval.
Need us to build a sensible package? Tell us your weight, current board, mast, front wing, conditions and what you are struggling with. We can help narrow the choices. Start with the complete Foil Drive buying guide or browse all foil assist options.