Attwood Marine Hydro-Stabilizer Hydrofoil Kit, Black Plastic, Stainless Steel Hardware

Overview

The Attwood Marine Hydro-Stabilizer is a bolt-on hydrofoil for outboards and stern drives that helps the boat climb onto plane more quickly, hold plane at lower RPM, and feel steadier through turns.

It mounts at the engine’s anti-ventilation plate and uses hydrofoil wings to add lift at the stern as speed builds. That can be useful on runabouts, fishing boats, tow-sport boats, and small cruisers that feel slow out of the hole, run bow-high, or lose grip during tight turns.

The range is split by engine size, with one version for 50 HP and above and one version for engines under 50 HP. Both versions use black molded plastic wings and include stainless steel bolts and lock nuts for installation.

Key features

• Helps the boat get on plane faster, which is useful when carrying passengers, gear, or pulling a skier from a stop.
• Helps keep the hull on plane at lower RPM, reducing the need to stay hard on the throttle once the boat is running level.
• Wing shape helps reduce ventilation in turns, giving the propeller a steadier bite during maneuvering.
• Made with black molded plastic wings for use around water and regular washdowns.
• Installs on a wide range of outboard and stern drive motors using the included stainless steel bolts and lock nuts.
• Available in two horsepower ranges so the stabilizer can be matched to smaller engines or 50 HP and above applications.

Variants

This Hydro-Stabilizer is offered in two configurations based on engine horsepower range.

The horsepower range is the key difference between the variants. The black molded plastic wing construction and included stainless steel mounting hardware are consistent across the range.

• 9400-7: Horsepower range 50 HP and above. This version is sized for larger outboards and stern drives where added stern lift can help the boat plane sooner and run with a more settled feel.
• 9401-7: Horsepower range under 50 HP. This version suits smaller outboards where planing speed, turn grip, and low-speed running attitude matter on light boats.

Installation and fit

Before installation, confirm the engine horsepower range and check the anti-ventilation plate for clear mounting space. The stabilizer is fastened with bolts and lock nuts, so alignment on the plate matters for a clean fit and balanced lift.

After mounting, run the boat through normal acceleration, cruising speed, and turns to check handling. Trim response can change after fitting a hydrofoil, so make small trim adjustments and note how the boat holds plane with passengers, fuel, and gear on board.

Use cases on board

This part is a practical match for boats that struggle to plane quickly, run bow-high during acceleration, or need better control while towing skiers or tubes. It is also useful for fishing boats and small cruisers that spend time at moderate speeds and benefit from staying on plane without excess throttle.

What’s included

• Hydro-Stabilizer wings
• Stainless steel bolts
• Lock nuts