Aerodynamic Boat Tail | Rear Flaps

What Is a Boat-Tail?

A boat-tail is a rear-mounted aerodynamic device fitted to the back of a trailer. Its purpose is to reduce air turbulence and drag as the vehicle moves, improving fuel efficiency and lowering emissions. Also known as "trailer flaps" or "aerodynamic rear fairings," boat-tails are typically foldable and extend rearwards by up to 500mm.

How Does It Work?

When a trailer travels at speed, air pressure builds at the front and drops sharply at the rear, creating drag. Boat-tails streamline this rear airflow by tapering the end of the trailer, reducing the vacuum effect and smoothing air separation.

This has a direct impact on fuel consumption and CO₂ emissions. In operational trials, fuel savings of around 7% have been recorded using boat-tail systems.

Benefits for Fleet Operators

Reduced fuel consumption (up to 7%+)
Lower CO₂ emissions
Supports sustainability targets and ESG reporting
Short return on investment (especially for long-haul)
Now fully legal on UK roads (per SI 2022/59)

Design and Practical Considerations

Don-Bur is familiar with a range of boat-tail solutions available on the market, including systems from Aerodyne, ZF (Optiflow), and TrailerTail. Designs vary, but typically feature:

Lightweight GRP or composite materials for strength and flexibility
Foldable or retractable mechanisms for safety and practicality
Compatibility with common trailer types (e.g. curtainsider, box van)

As with any rear-mounted equipment, operators should consider docking environments. In multi-dock or urban operations, the risk of accidental damage is higher. For trunking or motorway-based use, however, the benefits far outweigh the risks.

Where They Work Best

Boat-tails are particularly well suited to:

Double deck trailers (where rear-end drag is amplified)
Long-distance trunking routes
Operations with consistent trailer returns

Less suitable for:

Frequent urban deliveries with tight reversing
Unprotected loading bays with potential for impact

Trailer Compatibility and Options

Up to 500mm rear extension
Foldable design compliant with DfT guidance
Various systems available to suit fleet and operational needs

Why Choose Don-Bur?

With years of aerodynamic innovation experience, Don-Bur can advise on and integrate a wide range of aerodynamic devices tailored to your fleet. Whether using proprietary designs or third-party solutions such as Aerodyne, ZF Optiflow, or TrailerTail, we ensure each fitment matches your operational profile and performance goals.

Get in Touch

Contact us to learn more about aerodynamic boat-tail solutions and how they can contribute to your fuel savings and sustainability goals.

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